Amargo, Bitter-Ash, Bitter Wood, Bitterwood, Bois Amer, Cuasia, Écorce de Quassia, Jamaican Quassia, Palo de Cuasia, Pao Tariri, Picrasma, Picrasma excelsa, Quassia amara, Quassia Amer, Quassia Bark, Quassia de Jamaïque, Quassia de Surinam, Ruda, Surinam Quassia, Surinam Wood.


Overview Information

Quassia is a plant. The wood is used as medicine.

Quassia is used for treating an eating disorder called anorexia, indigestion, constipation, and fever. It is also used to rid the intestines of various kinds of worms; as a tonic or purgative; and as a mouthwash.

Some people apply quassia directly to the scalp for lice.

Rectally, quassia is used for treating worm infestations.

In manufacturing, quassia is used to flavor foods, beverages, lozenges, and laxatives. The bark and wood have been used as an insecticide.

How does it work?

Quassia contains chemicals that might increase stomach acid and bile secretions, perhaps accounting for appetite stimulant and digestive effects. Other chemicals may have activity against bacteria, fungi, and mosquito larvae.


Uses & Effectiveness?

Insufficient Evidence for

  • Lice. Early research suggests that applying quassia tincture one time can kill head lice. However, the lice might come back. Some research shows that two applications within one week might be more effective than a single application.
  • Appetite loss (anorexia).
  • Indigestion.
  • Constipation.
  • Fever.
  • Intestinal worms.
  • Other conditions.
More evidence is needed to rate the effectiveness of quassia for these uses.

Side Effects

Side Effects & Safety

Quassia is LIKELY SAFE when taken by mouth in food amounts. But quassia is POSSIBLY UNSAFE when taken by mouth in medicinal amounts. It can cause side effects such as irritation of the mouth, throat, and digestive tract along with nausea and vomiting. In very large doses, it could cause abnormal heart function; however, most people throw up before they get a high enough dose to cause heart problems. Long-term use can cause vision changes and blindness.

Quassia is POSSIBLY SAFE when used on the skin.

Special Precautions & Warnings:

Pregnancy and breast-feeding: Quassia is LIKELY UNSAFE when taken by mouth during pregnancy or breast-feeding. It can cause cell damage and nausea.

There is not enough reliable information about the safety of applying quassia to the skin or scalp you are pregnant or breast-feeding. Stay on the safe side and avoid use.

Digestive tract problems or diseases, such as stomach or intestinal ulcers, Crohn's disease, infections, and many other conditions: In large amounts quassia can irritate the digestive tract. Don’t use it if you have one of these conditions.



Moderate Interaction

Be cautious with this combination

  • Digoxin (Lanoxin) interacts with QUASSIA

    Quassia is a type of laxative called a stimulant laxative. Stimulant laxatives can decrease potassium levels in the body. Low potassium levels can increase the risk of side effects of digoxin (Lanoxin).

  • Water pills (Diuretic drugs) interacts with QUASSIA

    Quassia is a laxative. Some laxatives can decrease potassium in the body. "Water pills" can also decrease potassium in the body. Taking quassia along with "water pills" might decrease potassium in the body too much.
    Some "water pills" that can decrease potassium include chlorothiazide (Diuril), chlorthalidone (Thalitone), furosemide (Lasix), hydrochlorothiazide (HCTZ, HydroDiuril, Microzide), and others.

Minor Interaction

Be watchful with this combination

  • Antacids interacts with QUASSIA

    Antacids are used to decrease stomach acid. Quassia may increase stomach acid. By increasing stomach acid, quassia might decrease the effectiveness of antacids. Some antacids include calcium carbonate (Tums, others), dihydroxyaluminum sodium carbonate (Rolaids, others), magaldrate (Riopan), magnesium sulfate (Bilagog), aluminum hydroxide (Amphojel), and others.

  • Medications that decrease stomach acid (H2-Blockers) interacts with QUASSIA

    Quassia might increase stomach acid. By increasing stomach acid, quassia might decrease the effectiveness of some medications that decrease stomach acid, called H2-Blockers.
    Some medications that decrease stomach acid include cimetidine (Tagamet), ranitidine (Zantac), nizatidine (Axid), and famotidine (Pepcid).

  • Medications that decrease stomach acid (Proton pump inhibitors) interacts with QUASSIA

    Quassia might increase stomach acid. By increasing stomach acid, quassia might decrease the effectiveness of medications that are used to decrease stomach acid, called proton pump inhibitors.
    Some medications that decrease stomach acid include omeprazole (Prilosec), lansoprazole (Prevacid), rabeprazole (Aciphex), pantoprazole (Protonix), and esomeprazole (Nexium).



The appropriate dose of quassia depends on several factors such as the user's age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for quassia. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.

View References


  • Ajaiyeoba, E. O., Abalogu, U. I., Krebs, H. C., and Oduola, A. M. In vivo antimalarial activities of Quassia amara and Quassia undulata plant extracts in mice. J Ethnopharmacol. 11-30-1999;67(3):321-325. View abstract.
  • Apers, S., Cimanga, K., Vanden Berghe, D., Van Meenen, E., Longanga, A. O., Foriers, A., Vlietinck, A., and Pieters, L. Antiviral activity of simalikalactone D, a quassinoid from Quassia africana. Planta Med 2002;68(1):20-24. View abstract.
  • Gruenwald, J. and et al. PDR for Herbal Medicines. 1998;1
  • Jensen, O., Bjerregaard, P., and Nielsen, A. O. [Treatment of head lice with quassia tincture]. Ugeskr.Laeger 1-22-1979;141(4):225-226. View abstract.
  • Kitagawa, I., Mahmud, T., Yokota, K., Nakagawa, S., Mayumi, T., Kobayashi, M., and Shibuya, H. Indonesian medicinal plants. XVII. Characterization of quassinoids from the stems of Quassia indica. Chem.Pharm.Bull.(Tokyo) 1996;44(11):2009-2014. View abstract.
  • Leung, A. Y. and Foster, S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 1996;2nd ed.
  • Ninci, M. E. [Prophylaxis and treatment of pediculosis with Quassia amarga]. Rev Fac.Cien.Med Univ Nac.Cordoba 1991;49(2):27-31. View abstract.
  • Parveen, S., Das, S., Kundra, C. P., and Pereira, B. M. A comprehensive evaluation of the reproductive toxicity of Quassia amara in male rats. Reprod.Toxicol. 2003;17(1):45-50. View abstract.
  • Raji, Y. and Bolarinwa, A. F. Antifertility activity of Quassia amara in male rats - in vivo study. Life Sci 1997;61(11):1067-1074. View abstract.
  • Sugimoto, N., Sato, K., Yamazaki, T., and Tanamoto, K. [Analysis of constituents in Jamaica quassia extract, a natural bittering agent]. Shokuhin Eiseigaku Zasshi 2003;44(6):328-331. View abstract.
  • Toma, W., Gracioso, J. S., Hiruma-Lima, C. A., Andrade, F. D., Vilegas, W., and Souza Brito, A. R. Evaluation of the analgesic and antiedematogenic activities of Quassia amara bark extract. J Ethnopharmacol. 2003;85(1):19-23. View abstract.
  • Toma, W., Gracioso, Jde S., de Andrade, F. D., Hiruma-Lima, C. A., Vilegas, W., and Souza Brito, A. R. Antiulcerogenic activity of four extracts obtained from the bark wood of Quassia amara L. (Simaroubaceae). Biol Pharm.Bull. 2002;25(9):1151-1155. View abstract.
  • Electronic Code of Federal Regulations. Title 21. Part 182 -- Substances Generally Recognized As Safe. Available at: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=182
  • Evans DA, Raj RK. Larvicidal efficacy of Quassin against Culex quinquefasciatus. Indian J Med Res 1991;93:324-7. View abstract.
  • Jensen O, Nielsen AO, Bjerregaard P. Pediculosis capitis treated with quassia tincture. Acta Derm Venereol 1978;58:557-9. View abstract.
  • Matthys D, Van Coster R, Verhaaren H. Fatal outcome of pyruvate loading test in child with restrictive cardiomyopathy. Lancet 1991;338:1020-1. View abstract.

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CONDITIONS OF USE AND IMPORTANT INFORMATION: This information is meant to supplement, not replace advice from your doctor or healthcare provider and is not meant to cover all possible uses, precautions, interactions or adverse effects. This information may not fit your specific health circumstances. Never delay or disregard seeking professional medical advice from your doctor or other qualified health care provider because of something you have read on WebMD. You should always speak with your doctor or health care professional before you start, stop, or change any prescribed part of your health care plan or treatment and to determine what course of therapy is right for you.

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