Chan Su and Digoxin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Digoxin
Chan Su
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Increased risk of digoxin toxicity
Interaction Deep Dive
Chan-su (toad venom toxin), a bufadienolide, is cardioactive with properties similar to digitalis245. Ingestion or dermal absorption of toad venom (from Bufo species) has caused typical digitalis-like poisoning, with dysrhythmias, heart block, hypotension, and vomiting 678293. Additionally, Chan-Su may be incorrectly detected as digoxin at levels up to 0.5 nanograms/milliliter in some assays, resulting in falsely elevated digoxin levels. Consider using testing methods less susceptible to interference, such as LC/MS/MS 1.
Why it happens (mechanism)
Additive digitalis glycoside effect
Literature reports
4 reports — tap to read
a) Six previously healthy males between the ages of 17 and 40 presented with vomiting, bradycardia, and hypotension; several were hyperkalemic and 1 suffered a seizure. All exhibited positive serum digoxin concentrations. The substance they had ingested was an aphrodisiac called "love stone" or "rock hard", which was found to be identical to Chan-Su, a Chinese medication derived from toad venom. Four of the patients died of cardiac dysrhythmias. Two recovered after administration of digoxin immune Fab (Digibind(R)) 2.
b) A 65-year-old woman developed nausea, vomiting, diarrhea, general malaise, and abdominal pain 5 hours after consuming 50 tablets of kyushin, a traditional Chinese medicine containing Chan-Su (suicide attempt). Upon hospital admission her heart rate was 60 beats/minute, blood pressure was 140/70 mmHg. The ECG showed a second degree Wenckebach AV block and a flat T-wave which normalized the next day. The serum digoxin-like immunoreactive substance (DLIS) was 2.35 ng/mL 24 hours after ingestion (using the Digoxin II kit by Abbott Laboratories, Inc.). Serum electrolytes were normal. With supportive treatment, this gradually declined over 5 days and the patient was released on the eighth day 3.
c) A 34-year-old woman developed nausea, vomiting, and general malaise 2 hours after consuming approximately 50 pills of kyushin, a traditional Chinese medicine containing Chan-Su, during an attempted suicide. On admission to the hospital, her heart rate was 64 beats/minute, blood pressure was 110/70 mmHg. Serum DLIS 10 hours after consuming the drug was 1.84 ng/mL. This diminished to 0.67 ng/mL by the next day with supportive treatment and symptoms also subsided. Serum electrolytes were normal. All ECGs during hospitalization were normal 3.
d) The bufadienolides in toad venom (Chan-su) are presumed to be the cardioactive components of Chan-Su which has proven its ability to inhibit sodium, potassium, and ATPase activity 45.
Common questions
Can I take Chan Su and Digoxin together?
Increased risk of digoxin toxicity Always confirm with your pharmacist or prescriber before making any change.
How serious is the Chan Su and Digoxin interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Chan Su or Digoxin need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (9)
- Product Information: LANOXIN(R) intravenous injection, intramuscular injection, digoxin intravenous injection, intramuscular injection. Covis Pharmaceuticals, Inc. (per FDA), Cary, NC, 2013. DailyMed
- Brubacher JR, Ravikumar PR, Bania T, et al: Treatment of toad venom poisoning with digoxin-specific fab fragments. Chest 1996; 110(5):1282-1288. DOI
- Lin CS, Lin MC, Chen KS, et al: A digoxin-like immunoreactive substance and atrioventricular block induced by a Chinese medicine "Kyushin". Jap Circ J 1989; 53:1077-1080. PubMed
- Lichtstein P, Kachalsky S, & Deutsch J: Identification of a ouabain-like compound in toad skin and plasma as a bufodienolide derivative. Life Sci 1986; 38:1261-1270. DOI
- Palumbo NE, Perri S, & Read G: Experimental induction and treatment of toad poisoning in the dog. J Am Vet Med Assoc 1975; 167:1000-1005. DOI
- Du NT & Due P: Severe toad venom poisoning by dermal absorption (abstract). J Toxicol Clin Toxicol 2001; 39:563.
- Chi HT, Hung DZ, & Hu WH: Prognostic implications of hyperkalemia in toad toxin intoxication. Hum Exp Toxicol 1998; 17:343-346. PubMed
- Ko RJ, Greenwald MS, & Loscutoff SM: Lethal ingestion of Chinese herbal tea containing Ch'an su. West J Med 1996; 164:71-75.
- CDC: Deaths associated with a purported aphrodisiac-- City, February 1993-May 1995. CDC: MMWR 1995; 44:853-861.
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