Condurango

What is Condurango?

Condurango bark carries a positive German Commission E monograph for loss of appetite at an average daily dose of 3 grams of crude bark, while the condurango on a United States drugstore shelf is a 30C homeopathic pellet, a dilution factor of 10 to the 60th power. Those two things share a name and nothing else.

The plant is a woody Andean climber reaching 9 meters, its stem usually under 5 centimeters thick, which the 1873 Navy survey put under an inch, though some floras record exceptional stems to 60 centimeters. It has gray-brown bark flecked with white, opposite heart-shaped to arrow-shaped leaves, and yellowish-white bell-shaped flowers. Cut it and it bleeds milky latex, which becomes a safety point in section 7. It grows in deciduous forest in Ecuador, Peru and Colombia at roughly 1,000 to 2,000 meters.

Triana named it Gonolobus cundurango; Reichenbach the younger published it as Marsdenia cundurango in 1872, the name the pharmacopoeias kept. It has also circulated as Gonolobus condurango, Marsdenia condurango and Pseudomarsdenia cundurango. In 2020, Liede-Schumann and Keller transferred the South American species of Marsdenia into the resurrected genus Ruehssia in Phytotaxa volume 471, issue 3, making the currently accepted name Ruehssia cundurango. Asclepiadaceae, the family printed on most condurango labels and in most of the research papers, is no longer a family at all: it is Asclepiadoideae, a subfamily inside Apocynaceae, tribe Marsdenieae.

Common Names

• Condurango, cundurango, condor vine, eagle-vine bark, Kondorliane in German

• Condurango blanco, the trade grade historically treated as genuine, as against the several other barks sold under the same name

• Mata-perro, tue-chien, dog-killer, a name the 1873 Navy report attaches to condurango blanco itself, recording that the root and the seeds kill dogs. The bark is the article of commerce; the root and seed are not, which matters to anyone foraging

• Condurango Cortex, the Latin pharmacopoeial title, and Condurangorinde in German pharmacy

Primary Active Compounds

• Condurangin, not one compound but a mixture of C21 pregnane ester glycosides, reported at 1 to 3 percent of the bark in European Medicines Agency assessment EMEA/MRL/714/99-FINAL of January 2000, at 1.5 to 2.26 percent in Madaus's 1938 handbook

• Condurangoglycosides A, A0, C and C0. Condurango glycoside A is C53H78O17, PubChem CID 6450222, molar mass about 987 grams per mole

• The aglycones condurangogenin A (C32H42O7, molar mass 539 grams per mole) and condurangogenin C, plus marsdenin. Condurangoglycosides A and C carry a cinnamoyl group on the aglycone

• Conduritol, C6H10O4, a cyclohexene tetrol first isolated from this bark by K. Kübler in 1908 and named after the plant

• Chlorogenic acid, neochlorogenic acid, caffeic acid, p-coumaric acid, flavonoids, vanillin, volatile oil, sitosterol and caoutchouc

Key Note

These are pregnane glycosides, a different compound class from cardiac glycosides, and the distinction is load-bearing. Nerium oleander, Strophanthus and Thevetia are all Apocynaceae, so a reader who sees "glycoside" next to a milky-sapped vine may reasonably fear a digoxin-type effect. Condurangin has no reported action on the sodium potassium ATPase. Its documented toxic syndrome is gastrointestinal and neurological, not arrhythmic.

Condurango is a bitter with one regulatory indication, one documented allergy risk, a century and a half of failed cancer claims, and no controlled trial of any kind.

Primary Functions & Benefits

The bitter action, which is the only function with a regulatory monograph behind it

Condurangin is intensely bitter, and the mechanism claimed for it is the ordinary bitter reflex: taste receptor stimulation in the mouth and stomach increasing salivary and gastric secretion and raising appetite. The European Medicines Agency's 2000 summary report states the effect in exactly those terms, that the bitter taste stimulates appetite and promotes salivation and secretion of gastric juice. Commission E approved it for loss of appetite on that basis and for nothing else.

The qualifier is that this is a mechanism assertion, not a trial result. No controlled trial of condurango for appetite, dyspepsia, gastritis or anything else appears in the indexed literature as of October 2026. If you have read that Marsdenia has randomized trial evidence in lung and gastric cancer, that is true and it is about a different species; section 17 covers the trap.

Smooth muscle and secretory effects reported in old animal pharmacology

Madaus's 1938 Lehrbuch der biologischen Heilmittel records that condurangin increases the sensitivity of smooth muscle to sympathetic stimulation, inhibits peristaltic reflexes and increases gastric secretion. That is early twentieth century animal work measured with the methods of its period, and it is the origin of the stomachic indication rather than confirmation of it.

Forms & Standardization

Form determines whether you are holding a bitter or holding ethanol and sucrose.

Crude cut bark, the Commission E and Deutscher Arzneimittel-Codex form

Sold in German pharmacies as Condurangorinde, cut, with a Deutscher Arzneimittel-Codex specification. This is the preparation the Commission E monograph covers at an average 3 grams per day. Because the glycosides dissolve better cold than hot, the traditional preparation is a cold maceration or long decoction rather than a brief hot infusion. No marker-compound percentage is declared on retail bark anywhere, and there is no United States Pharmacopeia monograph.

Tincture, 1 part drug to 5 parts menstruum in 70 percent ethanol

German pharmacy compounded condurango tincture is conventionally a 1:5 preparation in 70 percent ethanol by volume, and Commission E's tincture quantity is 2 to 5 grams daily. Ethanol at 70 percent extracts the pregnane glycosides more completely than water, so a tincture and a water infusion are not interchangeable at equal gram weights of starting bark.

Fluid extract, the Japanese pharmaceutical form

German reference works give 2 to 4 grams daily of fluid extract and 0.2 to 0.5 grams of dry or aqueous extract. Japan still licenses a finished one: Condurango Fluidextract "SHISEIDOU" from Shishodo Pharmaceutical, Ministry of Health, Labour and Welfare product code 2333002X1019, classified among bitter stomachics and digestives. Condurango Cortex is itself an official crude drug of the Japanese Pharmacopoeia.

Vinum Condurango, the medicated wine

German practice included a recognized condurango wine, the clearest surviving signal of what this plant was for: a bitter aperitif before meals for someone not eating enough.

Homeopathic dilutions, which is what the word condurango now buys in the United States

Washington Homeopathic Products lists condurango pellets across both the decimal and centesimal ladders, up through 30C and the millesimal potencies, in a Food and Drug Administration drug listing whose marketing category is unapproved homeopathic. Boiron sells Condurango 30C in 80-pellet tubes, and the labeled use printed on it is cracks in the corner of the mouth. That label is a truncation. Boericke's materia medica, an American work and not a German one, assigns Condurango to painful cracks in the corner of the mouth, fissures at the muco-cutaneous outlets, epithelioma of the lip or anus, esophageal stricture, gastric ulceration, and cancer of the stomach. Boiron kept the mouth fissure. The cancer indication is still in the source text, which is how a reader with a cancer diagnosis gets pointed at this pellet.

Here is the arithmetic, stated once, because every other number in this issue depends on it.

• A C step is a hundredfold dilution. As the method literature states it, 1C is one part mother tincture mixed with 99 parts ethanol, and each subsequent step repeats that on the previous one

• 6C is 100 to the 6th, a factor of 10 to the 12th, one trillion

• 30C is 100 to the 30th, a factor of 10 to the 60th

• The Avogadro constant is 6.02214076 times 10 to the 23rd per mole. Divide 10 to the 60th by it and you get 1.66 times 10 to the 36th

• Condurangogenin A has molar mass 538.7 grams per mole. For one molecule of it to survive thirty hundredfold steps, the first flask would need about 1.66 times 10 to the 36th moles of it, which is 8.9 times 10 to the 35th kilograms, roughly 450,000 times the mass of the Sun

• 6C is different in kind, not just degree. A one molar solution taken to 6C is one picomolar, about 600 billion molecules per liter. Molecules are present. To deliver the 30 milligrams of glycoside implied by the Commission E daily dose, from a 1:10 homeopathic mother tincture of bark containing 1 to 3 percent condurangin, you would have to swallow 10 million to 30 million metric tons of 6C liquid

What standardization exists

None, in either category. Steinegger and Brunner published a method for determining condurangin in condurango bark and its preparations in Pharmaceutica Acta Helvetiae volume 52, pages 139 to 142, in 1977, so an assay has existed for about fifty years, and no retail product reports a result from it. Homeopathic manufacture is standardized on process instead: Deutsche Homöopathie-Union states that its dilutions follow the Homöopathisches Arzneimittelbuch and European Pharmacopoeia and that potentization is performed by hand. It makes no content claim, because at 30C there is no content to claim.

Food Sources

Condurango is not a food and has no nutritional role, so this section is routes of oral and dermal exposure.

Realistic exposure routes

What matters here is that the most likely United States exposure, a 6C or higher pellet, delivers sucrose and lactose and no measurable bark, while bulk bark and capsules carry no monograph quantity on the label at all, so nothing on the package stops a buyer going past the Commission E average of 3 grams per day.

The exposure route that caused the one documented serious harm

A beverage. Pfützner, Thomas, Rueff and Przybilla reported in the Journal of Allergy and Clinical Immunology in February 1998 an anaphylactic reaction elicited by condurango bark in an adult male health care worker already allergic to natural rubber latex. The plant is a latex-bearing Apocynaceae, and its bark contains caoutchouc, the same polymer class as natural rubber. That case report is the single most clinically actionable fact in this issue.

Whether dietary intake is sufficient

The question does not arise for a non-nutrient, but one comparison settles the matter. The European Medicines Agency's Committee on Herbal Medicinal Products adopted a European Union herbal monograph called Species amarae, reference EMA/HMPC/44543/2018, on 18 November 2020. Its indication is temporary loss of appetite, which is condurango's indication with the word temporary added, and its posology is 2 grams of the tea combination in 150 milliliters of boiling water three times daily, 30 minutes before meals. The monograph names eight plants, each with a percentage range: yarrow, wormwood, centaury, chicory, yellow gentian, white horehound, bogbean and dandelion. Condurango is not among them, and no European Union herbal monograph for condurango exists. European regulators wrote a document for precisely this job and picked eight other bitters.

Who Should Take Condurango

Nobody needs to take condurango, and the reason is not that it is dangerous. For the one indication approved anywhere, eight better-documented bitters carry a current European Union herbal monograph. For the indication people actually search it for, it does not work.

Who is sometimes given it, in the two countries where it is a licensed medicine

In Germany and Japan, an adult with poor appetite or functional dyspepsia may buy a condurango bitter preparation: loss of appetite is the German indication, bitter stomachic and digestive the Japanese classification. In both cases the product is bark with a declared drug to extract ratio, dispensed by a pharmacy, and both countries also stock gentian and wormwood preparations with more evidence behind them.

Who is most likely to be looking this up, and the direct answer to them

A person with a cancer diagnosis, or someone caring for one, who has found condurango described online as an anticancer plant or an esophageal cancer remedy. If that is you, this is the part that matters: there is no clinical trial of condurango for cancer. Not a negative one, not a small one. None, in any country, in the indexed literature, as of October 2026. What exists is cell-culture work and rat work, described precisely in section 20, plus an 1871 enthusiasm that the United States government investigated in 1873 and that collapsed. Nothing in that record supports taking condurango instead of, alongside, or while deferring oncologic treatment. The thing to raise with your oncology team is the specific worry that sent you looking, usually appetite, weight loss or swallowing, all three of which have real supportive-care answers.

Who Should AVOID or Use Caution

Contraindications

• Anyone with natural rubber latex allergy. This is the one hard contraindication with a published human case behind it: Pfützner and colleagues, Journal of Allergy and Clinical Immunology, February 1998, volume 101, part 1 of issue 2, pages 281 to 282, anaphylaxis after condurango bark in a latex-allergic adult. Condurango is a latex-bearing Apocynaceae and the bark contains caoutchouc. Anaphylaxis is not dose-dependent, so this applies to the bark, the tincture, the tea and the wine

• Anyone with a known allergy to other Apocynaceae latex, or to the latex-fruit group where cross-reactivity is established

• Pregnancy and breastfeeding. The European Medicines Agency's 2000 assessment lists the gaps by name: no information was provided on pharmacokinetics, reproductive toxicity, teratogenicity, mutagenicity, carcinogenicity, immunotoxicity, antimicrobial activity or residues. That is an absence of study, not a reassurance

• Children. Neither the German nor the Japanese licensing covers pediatric use, and no pediatric dose exists for any preparation

Use Caution

• Anyone who has bought condurango because of a cancer diagnosis. The hazard here is not the chemistry, it is the delay. The cancer claim reached the United States 155 years ago, in 1871, and goes back to Ecuador in 1869. It has never produced a clinical trial

• Anyone taking a quantity above the monograph. The crude drug is an emetic at excess, and section 14 gives the documented syndrome

• Anyone foraging or buying unauthenticated bark. At least ten different plants are sold under this name in Ecuador, and one historical trade grade was an Aristolochia, a genus containing aristolochic acid, a nephrotoxin and a Group 1 human carcinogen. Section 18 covers this

• Anyone with gastroesophageal reflux or active peptic ulcer. Bitters increase gastric acid secretion by design, the opposite of what these conditions need. This is mechanism-based, not a reported adverse event

Critical Safety Point

A health care worker with glove-induced latex allergy drank a condurango preparation and had an anaphylactic reaction, published in a mainstream allergy journal by a university dermatology clinic in Munich. Latex allergy is common in that occupational group, and nobody prints this on a bag of condurango bark. The homeopathic pellet, whatever else is true of it, does not carry this risk, because at 6C and above there is no protein left to react to.

Recommended Dosages

There is no recommended dose of condurango for cancer, for appetite in any country but Germany and Japan, or for anything a United States product is labeled for. Every number below is a quantity from a regulatory monograph or a historical pharmacopoeia for the bitter stomachic use, reproduced so you can check a label against it. None of them is a cancer dose, and no cell-culture or animal concentration from section 20 belongs in this section or has been put here.

Crude bark, Commission E

Average daily dose 3 grams of the drug, with 2 to 4 grams given as the range in the European Medicines Agency's 2000 summary report and in German reference works. Commission E was established in 1978, published 380 herbal monographs in the Bundesanzeiger between 1984 and 1994, and has not updated any since; the American Botanical Council issued the English edition in 1998. A monograph from that body is a 1990s expert consensus on traditional use, not a trial result.

Tincture, 1:5 in 70 percent ethanol

2 to 5 grams daily. The ratio matters: at 1:5, 5 grams of tincture corresponds to about 1 gram of bark, a third of the Commission E bark quantity.

Fluid extract

2 to 4 grams daily in German reference works. The United States Dispensatory of 1918 gave one fluidrachm, 3.9 milliliters. King's American Dispensatory of 1898 gave 5 to 30 drops.

Dry or aqueous extract

0.2 to 0.5 grams daily.

Decoction, historical

King's American Dispensatory of 1898: half an ounce of bark boiled down, in tablespoon doses three times daily. The 1871 Ecuadorian instruction sent to the State Department was to cut the stem small and boil it until the water reached the color of sherry wine or strong tea, a color endpoint rather than a concentration. The same letter warned that it cannot be given many days in succession, because it brings on nervous phenomena.

Homeopathic dilutions

There is no dose in the pharmacological sense, because at 6C and above there is no measurable substance. The usual direction is five pellets several times daily. No Commission E gram figure above converts into a number of pellets; the two systems are not on the same scale.

Duration

No evidence-based duration exists, because no trial has established one. The Species amarae monograph instructs that if symptoms persist beyond two weeks a doctor should be consulted, and two weeks is a defensible ceiling to borrow. Appetite loss has serious causes, and a bitter that has not helped in two weeks is not one that needs four.

Timing & Administration

Before meals, which follows from the mechanism

A bitter works through taste and early gastric reflex, so it is taken before eating rather than with food or after it. The European Union Species amarae monograph specifies 30 minutes before meals, three times daily, which is the only administration guidance in this area with a current European document behind it.

Do not mask the taste

Bitterness is the proposed active principle, not a side effect of it. Encapsulating a bitter bypasses the oral taste receptors the mechanism depends on, which makes a condurango capsule a less plausible delivery form than a tea, a tincture or a wine, independent of how much glycoside it contains.

Cold water, not boiling

The European Medicines Agency's 2000 report has the condurango glycosides more soluble in cold water than in warm, which inverts the normal herbal instruction. A long cold maceration extracts more condurangin than a five-minute hot steep.

Timeline of Effects

This section is short because the trial durations the format asks for do not exist for this plant.

Bitter effect, minutes

A bitter taste reflex is immediate. Salivation and gastric secretion follow within minutes of tasting, which is why the administration window is 30 minutes before a meal rather than hours. Whether that translates into more food eaten over days has not been measured for condurango in a controlled setting.

Appetite, and when to stop

Two weeks at the monograph quantity, judged on whether you are eating more. If not, stop, because no mechanism in the published record predicts a delayed benefit. The window is borrowed from the Species amarae monograph, and labeled as borrowed.

What this section deliberately does not contain

Timelines from the animal work. The rat studies in section 20 are experimental schedules in rats given a chemical carcinogen. They describe no human outcome, and converting them into weeks of self-treatment would be the most dangerous thing this issue could do.

Benefits of Taking Condurango

The documented benefit ceiling is the same as for any bitter: it may make you want to eat. There is no demonstrated benefit beyond that in a human being, and the one it was famous for does not exist. The rest of this section is history, told as history.

The 1871 episode, with names

In 1871 the Ecuadorian government, under President Gabriel García Moreno, offered the bark to the United States. The primary record sits in Foreign Relations of the United States for 1871: Minister Antonio Flores wrote to Secretary of State Hamilton Fish enclosing reports from a Dr. Casares in Loja province claiming cures of cancer of the lip, eye and leg plus scrofulous ulcers, intermittent fever and syphilis, and asked that the shipment be cleared through customs and analyzed.

The American promoter

Doctor Willard Bliss, a Washington physician whose first name was actually Doctor, Professor of Urinary Pathology in the Medical Department of Georgetown College, and later the man who attended President Garfield's gunshot wound in 1881, published "Cases of Cancer Treated with Cundurango" in the Boston Medical and Surgical Journal on 20 July 1871 and again in the American Journal of Dental Science that October, volume 5, issue 6, pages 276 to 279. E. Andrews, Professor of Surgery at Chicago Medical College, published a counter-assessment titled simply "Cundurango" in the Chicago Medical Examiner in December 1871, volume 12, pages 656 to 660.

The government investigation and the collapse

The State Department was the channel, not the sponsor. The Navy ran the inquiry: Surgeon-General William M. Wood instructed Passed Assistant Surgeon Joseph G. Ayers on 15 May 1871, and the Bureau of Medicine and Surgery published the result as "A Report on the Origin and Therapeutic Properties of Cundurango," Washington, 1873, under Ruschenberger's name. Its most consequential finding was botanical: at least ten different plants were sold under the name in Ecuador, so the bark being tested in American hospitals was not reliably one species. Material went out through the Smithsonian Institution and the medical departments of the Army and Navy. A syphilis patient at the naval hospital in Philadelphia took sixteen ounces of a fluid extract "without any observable effects of any kind," and the house-surgeon of Middlesex Hospital in London reported on it too. Ayers's own verdict closed it: the diagnosis in the most remarkable reported cases was too uncertain, and the use of the remedy too limited, to establish any curative value. Sevilla and Sevilla reconstructed the politics of the affair in Science in Context, volume 33, issue 4, pages 423 to 440, in 2020.

The German case that looked like a cure

Madaus's 1938 handbook records that in 1874 the physician Friedreich reported apparently complete healing of a gastric cancer patient after roughly four weeks of condurango, and records the later reinterpretation: the lesion was chronic gastric ulceration, not carcinoma. The most cited success in the European literature was a misdiagnosis, the normal fate of pre-endoscopic gastric cancer cures.

The verdicts, in order

Brunton, publishing "Physiological Action of Condurango" in the Journal of Physiology in April 1884, volume 5, pages 17 to 34, concluded that condurango blanco was inert. King's American Dispensatory in 1898 wrote that the agent, once so highly lauded as a positive remedy for cancer and syphilis, was rarely employed at the present time. The United States Dispensatory of 1918 wrote that further experience had demonstrated its uselessness. Necochea López traced the long tail in the Journal of the History of Medicine and Allied Sciences in 2025: a meteoric rise in the 1860s as a cancer specific, a fall, a persistence as a cancer adjuvant, a return to national pharmacopeias as a stomachic, and clinicians still complaining into the 1920s that the vine had never been given a fair trial. It had been given several. The stomachic use is what survived, and it is the only benefit column ever filled in.

Potential Negatives & Side Effects

Vomiting, the crude drug's characteristic excess effect

Madaus's 1938 handbook records that experimental condurangin produced salivation, vomiting, stiffness of the limbs, and convulsions with twitching of the facial muscles progressing to paralysis of the respiratory center. Vomiting is the first and most consistent sign of too much bark, which makes the crude drug largely self-limiting by mouth and is part of why there is almost no modern poisoning literature. Anaphylaxis in a latex-allergic person, covered in section 7, is the one serious documented adverse event and is not dose-related at all.

Neurological effects at overdose

The European Medicines Agency's 2000 summary report states that overdoses may cause convulsions ending in paralysis, along with vertigo and disturbed vision. That is a committee summary of older toxicology, not a case series, and the report gives no quantities at all, so no threshold can be read out of it.

Gastric acid and ethanol

A bitter that increases gastric secretion can worsen reflux and ulcer symptoms, predicted by the mechanism rather than reported in any condurango case series. Separately, a 70 percent ethanol tincture at 5 grams daily delivers roughly 3 grams of ethanol: trivial for most adults, not trivial with liver disease, on disulfiram or metronidazole, or in recovery.

Side effects of the homeopathic product

None are plausible from the active ingredient, because there is no active ingredient present at 6C and above. The reported side effect profile of a 30C pellet is the profile of sucrose and lactose, which matters for one group: people with lactose intolerance taking large numbers of pellets.

Deficiency Symptoms

There is no condurango deficiency, because condurango has no role in human physiology. No deficiency state has ever been described, and no assay of condurango status exists or could exist.

What condurango addresses

Nothing deficient. It is proposed to act on a function, appetite, not to replace a missing substance. Contrast a genuine trace element: zinc has a deficiency state that includes loss of appetite and impaired taste, a measurable serum concentration, repletion trials, and a United States Recommended Dietary Allowance of 11 milligrams per day for adult men and 8 for adult women. Condurango has none of that architecture: no biomarker, no requirement, no repletion trial.

Bottom line

If appetite loss is the symptom, the useful next step is finding out why: thyroid disease, depression, medication effect, zinc or B12 status, malignancy. A bitter sits on top of that answer, never in place of getting it.

Toxicity Symptoms

Condurango is not a cumulative toxin and no chronic poisoning syndrome is described for it. What exists is an acute excess picture from the crude glycoside, documented in old experimental work, plus one immunologic emergency that is not dose-related at all.

At high intake

• Salivation and vomiting first, recorded in Madaus's 1938 handbook as the experimental effect of condurangin, with stiffness of the limbs at higher quantities, then convulsions, and at the top of Madaus's range paralysis of the respiratory center. The emetic threshold is the practical ceiling on oral self-dosing

• The European Medicines Agency's 2000 report adds vertigo, disturbed vision, and convulsions progressing to paralysis as overdose features

• Two isolated condurango glycosides had median lethal doses of 75 and 375 milligrams per kilogram in the toxicology that report summarizes, a fivefold spread between purified compounds from the same bark, which shows how little the word condurangin pins down. That report does not give the route

• Madaus records poisoning signs 15 to 30 minutes after intravenous dosing but several hours after oral dosing, consistent with incomplete absorption of large polar glycosides

Signs to reduce or stop

Stop at nausea or vomiting, at any lightheadedness or visual disturbance, and immediately at swelling of the lips, tongue or throat, hives, wheeze or faintness, which in a latex-allergic person is the anaphylaxis pattern from the 1998 case report and is an emergency rather than a reason to halve the dose.

General note

Three gaps deserve naming. No repeated-dose oral toxicity study of condurango bark exists: the European Medicines Agency recorded in January 2000 that no acute or repeated dose toxicity reports were provided, and none has appeared since. It has never been through a bacterial mutagenicity assay either, another gap the same document records. And the scarcity of modern poisoning reports is not evidence of safety, because a substance almost nobody takes generates almost no case reports whether it is safe or not. Nothing in this section is a reassurance that is a finding rather than an absence.

How Condurango Works

The bitter reflex, the only proposed mechanism for the approved use

Condurangin stimulates bitter taste receptors in the mouth and upper gastrointestinal tract, and the reflex response is increased salivary flow and gastric secretion, with appetite following, as section 3 sets out. The point here is that this is a reflex and not a systemic drug effect, which is why the administration window is minutes before a meal and why swallowing the bitter in a capsule should blunt it.

Why the molecular class matters

Condurangoglycosides are C21 pregnane ester glycosides: a pregnane steroid aglycone esterified with cinnamic or acetic acid, carrying three or four deoxygenated sugars, a signature of the Asclepiadoideae. Large polar glycosides of this size, around 987 grams per mole for condurango glycoside A, are poorly absorbed intact from the gut, which fits the oral-versus-intravenous timing in section 14. Whatever condurango does by mouth, it most likely does at the mucosal surface rather than in the bloodstream.

What is not known about the mechanism

Everything downstream of the taste receptor. There is no pharmacokinetic study of condurango in any species. Absorption, distribution, metabolism, excretion and plasma concentration are all unmeasured, which the European Medicines Agency stated plainly in January 2000 and which remains true. A mechanism with no pharmacokinetics attached cannot support any claim about systemic effects, including every claim this plant is famous for.

Synergistic Supplements

Nothing. No combination of condurango with any other supplement, herb or drug has been tested in a human being for any outcome.

One in vitro combination study exists, named here only so it is not mistaken for more. Maqbool and colleagues reported in the Asian Pacific Journal of Cancer Prevention in 2021, volume 22, issue 3, pages 843 to 852, that combined Aloe barbadensis and Marsdenia condurango extracts reduced viability in HeLa and HepG2 cells at a lower combined concentration than either alone. That is two plant extracts in a dish of immortalized cells. It establishes nothing about a person.

Interactions & What NOT to Take

Documented drug interactions: none, and the reason is that nobody has looked

There is no published interaction study of condurango with any drug, and no pharmacokinetic data from which to predict cytochrome P450 or transporter effects. Natural Medicines lists none. That is a blank record, not a clean one.

Mechanism-based cautions worth taking seriously

• Proton pump inhibitors and H2 blockers. A bitter is given to increase gastric acid secretion; omeprazole, pantoprazole and famotidine are given to suppress it. The two purposes are opposed, which does not make the combination dangerous but does make it pointless

• Disulfiram and metronidazole, with the 70 percent ethanol tincture rather than with the plant

• Any drug whose absorption is pH-sensitive, including ketoconazole and itraconazole, on the same reasoning and caveat

What not to take it instead of

Oncologic treatment, for any cancer, at any stage. No case series documents this for condurango specifically, which is exactly why it belongs here rather than in the toxicity section: the mechanism of harm is elapsed time, and nothing measures it.

One naming trap to avoid

Do not read trial evidence for Marsdenia tenacissima as evidence for Marsdenia condurango. The Chinese species, sold as Tongguanteng and as Xiaoaiping injection, has a large randomized literature in non-small-cell lung and gastric cancer, including a 2019 systematic review of 17 trials in 1,329 gastric cancer patients and a 2025 network meta-analysis of 165 randomized trials of five Chinese herbal injections in non-small-cell lung cancer, Marsdenia tenacissima among them. Different plant, different preparation, different chemistry, and in several of those regimens an injection given with chemotherapy. None of it transfers.

Quality, Testing & Adulteration

The documented substitution problem, 153 years old since the 1873 report and never solved

The 1873 United States Navy report on cundurango, from Joseph G. Ayers's investigation, found at least ten different plants sold under the name in Ecuador, collected around Loja, Malacatos, Zaruma and Guayaquil. The United States Dispensatory of 1918, citing the same investigation, printed the country as Colombia. The Dispensatory named two substitute trade grades: Guayaquil condurango, bark and woody branch fragments believed to come from an asclepiadaceous plant close to Gonolobus, and Mexican condurango, split stems or thin adherent bark thought to be yielded by an Aristolochia.

That second one is the serious finding. Aristolochia species contain aristolochic acid, which the International Agency for Research on Cancer places in Group 1, carcinogenic to humans, along with plants containing it, on the basis of upper urinary tract urothelial carcinoma and nephropathy. A bark trade in which a tonic sold for cancer was sometimes an Aristolochia is the worst substitution available here, and nothing demonstrates it has stopped, because nobody is checking.

What third-party testing exists

None specific to condurango. There is no United States Pharmacopeia monograph, no NSF or ConsumerLab program covering it, and no European Union herbal monograph to test against. German pharmacy bark is dispensed against a Deutscher Arzneimittel-Codex specification, the only retail quality framework this drug has anywhere.

What a certificate of analysis would need to show

Botanical identification to species by microscopy or DNA barcoding, because ten plants share the name; a condurangin content figure, for which a method exists; and heavy metal and microbial limits. In practice a condurango certificate reports identity by inspection and nothing quantitative, because there is no accepted specification limit to pass or fail.

What a buyer can confirm before paying

• Whether a species name appears at all, and whether it is a real one. Accept Ruehssia cundurango, Marsdenia cundurango, Marsdenia condurango or Gonolobus condurango. Treat a product that says only "condurango bark" as unidentified

• For a tincture, whether the drug to extract ratio and the ethanol percentage are printed. The German pharmacy convention is 1:5 in 70 percent ethanol. No ratio means no dose

• For a homeopathic product, the potency notation, which tells you exactly what is in it. Each X step is a tenfold dilution, each C step a hundredfold. Up to about 5X there is measurable plant material; from roughly 6X or 3C the content falls below any assay; and from 24X or 12C upward, Avogadro's number makes a single surviving molecule improbable. So 2X through 5X contain bark. Everything from 6C up does not, and neither does the 30X on the same shelf

• Whether a lot or batch number is on the package. The 2025 Hannover study cited its material down to the batch: mother tincture batch 1090819, C6 batch 330235469, C30 batch 330235547, D6 batch 0050720, all from Deutsche Homöopathie-Union in Karlsruhe. That is what traceable looks like, and most bulk bark has nothing comparable

Special Considerations

United States regulatory status, which changed recently and matters

Condurango reaches United States consumers almost entirely as an unapproved homeopathic drug. The Food and Drug Administration withdrew Compliance Policy Guide 400.400, the 1988 document, in a Federal Register notice published 25 October 2019, and finalized replacement guidance, "Homeopathic Drug Products: Guidance for FDA Staff and Industry," in December 2022 under docket FDA-2017-D-6580. That guidance states that there are currently no homeopathic drug products approved by the agency, sets out a risk-based enforcement approach, and makes clear that conformity to Homeopathic Pharmacopoeia of the United States dilution standards does not place a product outside the enforcement priorities.

Six categories are prioritized, and condurango marketed for cancer would fall into two at once: products for serious or life-threatening diseases, and products for vulnerable populations. A pellet labeled for cracks in the corner of the mouth is low priority. The same pellet marketed for esophageal or stomach cancer is not.

The cosmetic route

Marsdenia condurango bark extract has an International Nomenclature of Cosmetic Ingredients listing and appears in topical products. Nothing here applies to that use except the latex allergy point, which applies more rather than less when the material contacts skin.

Research Status & Evidence Quality

Tier 1, randomized controlled trials in humans: zero

No controlled trial of condurango for any indication appears in the indexed literature as of October 2026. A PubMed search filtered to clinical trial and randomized controlled trial publication types returns a single record, and it is Marsdenia tenacissima, retrieved because PubMed maps condurango to the Marsdenia subject heading. Widen the filter to systematic reviews and meta-analyses and you get four, same species.

Tier 2, controlled human studies of any design: zero. The closest records are a two-patient case report, Abad Lopez, "Condurango in cancer, with report of two cases," Journal of the American Institute of Homeopathy, 1963, volume 56, pages 356 to 359, and a one-paragraph prescribing letter, Bockus, "Rx: fluid extract of Condurango," Gastroenterology, September 1978, volume 75, page 553.

Tier 3, animal studies: a small number, all in chemically induced models

Sikdar, Mukherjee and Khuda-Bukhsh at the University of Kalyani fed rats benzo[a]pyrene by gavage at 50 milligrams per kilogram for one month, waited until lung tumors developed at four months, then gave either ethanolic condurango extract or Condurango 30C for one, two or three further months, reporting tissue recovery and caspase-3-mediated apoptosis. The Japanese company Zenyaku Kogyo tested isolated condurango glycosides against subcutaneous solid Ehrlich carcinoma in male mice at 8, 16 and 32 milligrams per kilogram intraperitoneally for ten days, patented as US 4,452,786. Every number here describes a rodent given a carcinogen or a transplanted tumor, by injection in the mouse work, and none is a human result or a human dose.

Tier 4, cell culture: the bulk of the modern literature, and where the dilution question gets answered

Each concentration below applies to cells in a dish and to nothing else. Sikdar and colleagues, Environmental Toxicology and Pharmacology, 2014, volume 37, issue 1, pages 300 to 314, used a glycoside-rich condurango fraction on H460 non-small-cell lung cancer cells at a 24-hour half-maximal inhibitory concentration of 0.22 micrograms per microliter. Sikdar and colleagues, Pharmacognosy Magazine, 2015, volume 11, supplement 1, pages S73 to S85, tested the pure aglycone condurangogenin A, found its inhibitory concentrations in A549 and H522 cells too high and too toxic to work with, and moved all experiments to H460 at 32 micrograms per milliliter, roughly 59 micromolar. Bishayee and colleagues, Journal of Pharmacopuncture, 2013, volume 16, issue 4, pages 7 to 13, reported that Condurango 30C reduced histone deacetylase 2 activity in HeLa cells at a 2 percent dose while leaving histone deacetylase 1 unchanged. Nobody has reproduced that; the next subsection covers the attempt.

The independent replication, which is the most informative study on this plant

Vajen, Schäffer, Eilers, Schlegelberger and Skawran at Hannover Medical School published an independent test of those claims in BMC Complementary Medicine and Therapies in May 2025, volume 25, article 177. They bought commercial Deutsche Homöopathie-Union material by batch, tested the mother tincture at 2 percent alongside D6, C6 and C30, and used trichostatin A, vorinostat and romidepsin as positive controls with ethanol as vehicle. They characterized histone deacetylase expression and acetylation across three triple-negative breast cancer lines against MCF12A, a non-tumorigenic breast line, then ran the condurango experiments in HCC38 and HeLa. The results split along the preparation line. The mother tincture at 2 percent induced apoptosis 2.5-fold in HCC38 cells at 12 hours, the same magnitude as trichostatin A, which is a laboratory tool compound and has never been a human medicine. The C6, D6 and C30 dilutions produced no increase in apoptosis in either cell type, no condurango preparation increased histone acetylation in HCC38 or HeLa, and none induced the tumor-suppressive microRNAs miR-192 or miR-194. The authors could not validate the proposed histone deacetylase inhibitor role, and they are careful about why. Their assay measured global acetylation, and they note that inhibiting one enzyme need not show up in that measurement, so the earlier histone deacetylase 2 claim is untested by their method rather than refuted. What they contradict head-on is the earlier report of apoptosis in HeLa cells at C30, and they call for further independent studies. Their own limitations section is blunt: cell culture says nothing about absorption or metabolism, and no animal model was run.

Research Limitations

• The evidence base is one research group. Most of the modern condurango literature comes from a single laboratory at the University of Kalyani, much of it in low-circulation complementary medicine journals, and one 2013 paper lists a co-author affiliated with a homeopathic manufacturer

• One of those papers required a published correction. The Journal of Pharmacopuncture issued an erratum in 2015, volume 18, issue 2, pages 86 to 87, because the 2014 rat paper was printed with a Methods abstract describing 15 male and 15 female Sprague-Dawley rats given 0.28 milligrams per kilogram of Sweet Bee Venom for 13 weeks, an entirely different experiment. The corrected protocol states the dose as Condurango 0.06 milliliters twice daily, a volume with no stated extract concentration, so the administered quantity of drug is not recoverable from the paper

• Several experiments are dosed in units that cannot be converted. A half-maximal inhibitory concentration reported as 2.43 microliters per 100 microliters of a 30C dilution is a volume fraction of a preparation containing no measurable substance, so it is not a concentration of anything

• No study tests the question a buyer has. The in vitro work that shows activity uses crude extract, a glycoside-rich fraction or a purified compound at micromolar concentrations, while the products on sale in the United States are 6C and above

• Cell-line cytotoxicity at tens of micromolar is a weak signal, not a drug lead; a clinical cytotoxic typically works at nanomolar concentrations. Condurangogenin A was not even consistently potent, being described by its own investigators as too toxic to work with in two of three lung lines

Summary & Key Takeaways

Condurango is an Andean vine whose bark is a genuine bitter with a positive German Commission E monograph for loss of appetite at 3 grams of drug a day, and a 155-year record of failed cancer claims that began with a diplomatic shipment to the United States State Department in 1871 and was dismantled by 1918. Its bitter principle is condurangin, 1 to 3 percent of the bark. Japan still licenses a condurango fluid extract as a stomachic, and when European regulators wrote a monograph for exactly this indication in November 2020 they named eight other bitters.

What a United States buyer gets is a different object. A 30C pellet is a dilution of 10 to the 60th, which is to say no bark at all, and the labeled use on the shelf is cracks in the corner of the mouth. In May 2025 a Hannover Medical School group put the mother tincture and the 6C, D6 and 30C dilutions on the same plates with proper positive controls. The tincture killed cells. That was a 2 percent solution of tincture bathing cells in a dish for twelve hours, and no oral dose puts anything like that concentration anywhere in the body, because the emetic ceiling arrives first. The dilutions did nothing, in any assay, at any time point.

Bottom Line

If you have a cancer diagnosis and found condurango online, this plant has nothing for you, and the reason is arithmetic and history rather than caution: no clinical trial of condurango for any indication exists, and the product sold under the name contains no bark. If you want a bitter for poor appetite, the Species amarae monograph gives you eight plants with a current regulatory document and a posology, and condurango is not one of them.

Key Safety Points

• Do not take condurango in any bark-containing form if you are allergic to natural rubber latex. One published anaphylaxis case, Munich, 1998, in a latex-allergic health care worker who drank it

• Vomiting is the first sign of too much crude bark, followed at higher experimental quantities by vertigo, disturbed vision and convulsions. Stop at nausea

• Avoid in pregnancy, breastfeeding and children, because the data do not exist rather than because a hazard was found

• Do not buy unidentified bark. At least ten plants are sold under this name in Ecuador, and one historical trade grade was an Aristolochia, a genus whose aristolochic acid the International Agency for Research on Cancer places in Group 1

• Never read Marsdenia tenacissima trial evidence as condurango evidence

Special Note

Two products carry one name and each fails for an opposite reason. The bark has a plausible mechanism, a regulatory monograph, a documented emetic ceiling, one documented anaphylaxis, and not a single controlled trial in 155 years. The 30C has no mechanism, no measurable content and no plausible harm, and it inherits the bark's reputation without inheriting a molecule of it. A reader told that condurango has research behind it has been told something true about a dish of cells and something false about themselves.

Researched and drafted with AI assistance. Every claim verified against primary sources and human-reviewed before publication. Last reviewed date posted. Corrections: reply to any issue.

This issue is educational and is not medical advice. If you have a cancer diagnosis, take prescription medication, are pregnant or breastfeeding, or have a latex allergy, talk to a clinician before taking condurango in any form.