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Horse Chestnut
What is it? Overview Usage Side Effects and Warnings

Horse Chestnut Side Effects and Warnings

Written by FoundHealth.

Safety Issues

Whole horse chestnut is classified as an unsafe herb by the FDA. Eating the nuts or drinking a tea made from the leaves can cause horse chestnut poisoning, the symptoms of which include nausea, vomiting, diarrhea, salivation, headache, breakdown of red blood cells, convulsions, and circulatory and respiratory failure possibly leading to death. 1 However, manufacturers of the typical European standardized extract formulations remove the most toxic constituent (esculin) and standardize the quantity of aescin. To prevent stomach irritation caused by another ingredient of horse chestnut, the extract is supplied in a controlled-release product, which reduces the incidence of irritation to below 1%, even at higher doses. 2 Properly prepared horse chestnut products appear to be quite safe. 3 After decades of wide usage in Germany, there have been no reports of serious harmful effects, and even mild reported reactions have been few in number.

In animal studies, horse chestnut and its principal ingredient aescin have shown a low degree of toxicity, producing no measurable effects when taken at dosages seven times higher than normal. 4 Dogs and rats have been treated for 34 weeks with this herb without harmful effects.

Individuals with severe kidney problems should avoid horse chestnut. 5 6 In addition, injectable forms of horse chestnut can be toxic to the liver. 7 The safety of horse chestnut in young children and pregnant or nursing women has not been established. However, 13 pregnant women were given horse chestnut in a controlled study without noticeable harm. 8 Furthermore, studies in pregnant rats and rabbits found no injury to embryos at doses up to 10 times the human dose, and changes of questionable significance at 30 times the dose. 9 Horse chestnut should not be combined with anticoagulant, or blood-thinning, drugs, as it may amplify their effect. 10

Interactions You Should Know About

  • If you are taking aspirin , clopidogrel (Plavix), ticlopidine (Ticlid), pentoxifylline (Trental), or anticoagulant drugs such as warfarin (Coumadin) or heparin : Do not use horse chestnut except under medical supervision.


  1. Chandler RF. Horse chestnut. Can Pharm J. 1993;126:297-300, 306.
  2. Diehm C. The role of oedema protective drugs in the treatment of chronic venous insufficiency: a review of evidence based on placebo-controlled clinical trials with regard to efficacy and tolerance. Phlebology. 1996;11:23-29.
  3. Hitzenberger G. The therapeutic effectiveness of chestnut extract [translated from German]. Wien Med Wochenschr. 1989;139:385-389.
  4. Hitzenberger G. The therapeutic effectiveness of chestnut extract [translated from German]. Wien Med Wochenschr. 1989;139:385-389.
  5. Grasso A, Corvaglia E. Two cases of suspected toxic tubulonephrosis due to Escine [in Italian;English abstract]. Gazz Med It. 1976;135:581-584.
  6. Reynolds JF, ed. Martindale, the Extra Pharmacopeia. London, England: Pharmaceutical Press; 1989:1539-1540.
  7. Takegoshi K, Tohyama T, Okuda K, Suzuki K, Ohta G. A case of Venoplant-induced hepatic injury. Gastroenterol Jpn. 21(1):62-5.
  8. Schulz V, Hansel R, Tyler VE. Rational Phytotherapy: A Physicians' Guide to Herbal Medicine. 3rd ed. Berlin, Germany: Springer-Verlag; 1998:132.
  9. Hitzenberger G. The therapeutic effectiveness of chestnut extract [translated from German]. Wien Med Wochenschr. 1989;139:385-389.
  10. Brinker F. Herb Contraindications and Drug Interactions: With Appendices Addressing Specific Conditions and Medicines. 2nd ed. Sandy, Ore: Eclectic Medical Publications; 1998:84.


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