Table of Contents > Herbs & Supplements > Quassia (Picraena excelsa, Quassia undalata, Quassia amara) Print

Quassia (Picraena excelsa, Quassia undalata, Quassia amara)


Also listed as: Picrasma, Jamaican quassia
Related terms

Related Terms
  • Ailanthus, amargo, bitter ash, bitter bark, bitterholz, bitterwood, bois amer, gorzkla, indaquassin, Jamaican quassia,Jamaica quassia extract, kvassia, kwassi, neoquassin, palo muneco, pau amarelo, pau quassia, pao tariri, picrasma, quassia africana, quassia amarga, quassia bark, quassia indica, Quassia undalata, quassia undulate, quassia wood, quassin, quassinoids, ruda, samaderines, simarinolide, Simaroubaceae (family), Surinam quassia, Surinam wood.

  • Quassia, a tree native to Jamaica and its neighboring islands, has traditionally been used as a remedy for roundworms, as an insecticide, and in brewing as a substitute for hops. It has also been used as a bitter digestive aid and a remedy for digestive disorders, parasites, and head lice.
  • Several early studies performed on quassia verified its traditional use as a natural insecticide, documenting it as an effective treatment for head lice in humans. Since quassia has long been used for malaria in South America, researchers studied this biological effect as well. One study showed strong antimalarial activity in mice.
  • There is early evidence that quassia may be useful in the treatment of leukemia or gastric ulcers. Quassia may also have pain-relieving, muscle relaxing, and sedating effects, but human clinical trials are currently lacking.

Evidence Table

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. GRADE *

Early evidence suggests the effectiveness of quassia for head lice. More well-designed clinical trials are necessary to confirm these finding and make a firm conclusion regarding the safety and effectiveness for this condition.

* Key to grades

A: Strong scientific evidence for this use
B: Good scientific evidence for this use
C: Unclear scientific evidence for this use
D: Fair scientific evidence for this use (it may not work)
F: Strong scientific evidence against this use (it likley does not work)

Tradition / Theory

The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.

  • Amenorrhea (absence of menstruation), analgesic (reduces pain), anorexia (eating disorder), antibacterial, anti-fertility, antifungal, antimalarial, antivenom, antiviral, constipation, fever, flavoring agent, hypoglycemic (blood sugar-lowering), hepatoprotection (liver protection), indigestion, insecticide (larvae), kidney stones, laxative, leukemia, muscle relaxant, parasites, pesticides, salivary stimulant, sedative (causes drowsiness), tonic, ulcers, worms.


Adults (18 years and older):

  • There is no proven safe or effective dose for quassia in adults.

Children (younger than 18 years):

  • There is no proven safe or effective dose for quassia in children. There is one report of death associated with quassia administered to a child via IV (through a vein).


The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.


  • Avoid in individuals with a known allergy or hypersensitivity to quassia or its constituents.

Side Effects and Warnings

  • Quassia is likely safe when consumed in amounts found in foods and beverages. It has Generally Recognized as Safe (GRAS) status in the United States.
  • Quassia appears to have a very mild side effects profile. The most common side effects are nausea and vomiting, due to its bitter taste. There have also been reports of mucous membrane irritation.
  • Quassia may cause drowsiness or sedation. Use cautiously if driving or operating heavy machinery. Long-term use of quassia may cause vision changes and blindness
  • Use cautiously with cardiac (heart) medications and blood thinners.
  • Avoid in people who are pregnant, and in males and females trying to become pregnant due to quassia's potential antifertility effects.
  • Avoid intravenous use in cardiomyopathy (heart disease) patients.

Pregnancy and Breastfeeding

  • Avoid quassia if pregnant or breastfeeding, due to a lack of available scientific evidence. Quassia may have antifertility effects in men and women.


Interactions with Drugs

  • Quassia may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs (NSAIDS) such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).
  • Quassia may interact with antacid medications and has been known to cause gastrointestinal adverse effects, use cautiously.
  • Quassia may interact with heart medications. Use cautiously in patients with heart conditions or taking cardiac agents, due to possible adverse effects.
  • Quassia may interact with diuretics; use cautiously.
  • Quassia may interact with hormonal agents. Use cautiously in male and female patients in couples trying to become pregnant.
  • Quassia may increase the amount of drowsiness caused by some drugs. Examples include benzodiazepines such as lorazepam (Ativan®) or diazepam (Valium®), barbiturates such as phenobarbital, narcotics such as codeine, some antidepressants, and alcohol. Caution is advised while driving or operating machinery.
  • Quassia may interact with laxatives; use cautiously.

Interactions with Herbs and Dietary Supplements

  • Quassia may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding.
  • Quassia may interact with herbs and supplements taken to prevent or treat various heart conditions.
  • Use cautiously with herbs and supplements with diuretic effects.
  • Quassia may interact with hormonal agents. Use cautiously with herbs and supplements with known hormonal activity, due to possible additive effects. Quassia may have negative effects on fertility in males and females.
  • Theoretically, abuse of horsetail or licorice along with quassia might increase risk of cardiac toxicity (heart damage).
  • Quassia my increase the amount of drowsiness cause by some herbs or supplements. Caution is advised when driving or operating heavy machinery.
  • Use cautiously with herbs or supplements with laxative effects.

  • This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (

  1. Ajaiyeoba EO, Krebs HC. Antibacterial and antifungal activities of Quassia undulata and Quassia amara extracts in vitro. Afr.J Med Med Sci 2003;32(4):353-356. .
  2. Ajaiyeoba EO, Abalogu UI, Krebs HC, et al. In vivo antimalarial activities of Quassia amara and Quassia undulata plant extracts in mice. J Ethnopharmacol. 11-30-1999;67(3):321-325. .
  3. Apers S, Cimanga K, Vanden Berghe D, et al. Antiviral activity of simalikalactone D, a quassinoid from Quassia africana. Planta Med 2002;68(1):20-24. .
  4. Bertani S, Bourdy G, Landau I, et al. Evaluation of French Guiana traditional antimalarial remedies. J Ethnopharmacol 4-8-2005;98(1-2):45-54. .
  5. Cabral JA, McChesney JD, Milhous WK. A new antimalarial quassinoid from Simaba guianensis. J Nat Prod. 1993;56(11):1954-1961. .
  6. De Cupere F, Vandebroek I, Puentes M, et al. Evaluation of vegetal extracts as biological herbi- and pesticides for their use in Cuban agriculture. Meded.Rijksuniv.Gent Fak.Landbouwkd.Toegep.Biol Wet. 2001;66(2a):455-462. .
  7. Heck AM, DeWitt BA, Lukes AL. Potential interactions between alternative therapies and warfarin. Am J Health Syst.Pharm 7-1-2000;57(13):1221-1227. .
  8. Kitagawa I, Mahmud T, Yokota K, et al. Indonesian medicinal plants. XVII. Characterization of quassinoids from the stems of Quassia indica. Chem.Pharm.Bull.(Tokyo) 1996;44(11):2009-2014. .
  9. Njar VC, Alao TO, Okogun JI, et al. Antifertility activity of Quassia amara: quassin inhibits the steroidogenesis in rat Leydig cells in vitro. Planta Med 1995;61(2):180-182. .
  10. Parveen S, Das S, Kundra CP, et al. A comprehensive evaluation of the reproductive toxicity of Quassia amara in male rats. Reprod.Toxicol. 2003;17(1):45-50. .
  11. Raji Y, Bolarinwa AF. Antifertility activity of Quassia amara in male rats - in vivo study. Life Sci 1997;61(11):1067-1074. .
  12. Sugimoto N, Sato K, Yamazaki T, et al. [Analysis of constituents in Jamaica quassia extract, a natural bittering agent]. Shokuhin Eiseigaku Zasshi 2003;44(6):328-331. .
  13. Toma W, Gracioso JS, Hiruma-Lima CA, et al. Evaluation of the analgesic and antiedematogenic activities of Quassia amara bark extract. J Ethnopharmacol. 2003;85(1):19-23. .
  14. Toma W, Gracioso Jde S, de Andrade FD, et al. Antiulcerogenic activity of four extracts obtained from the bark wood of Quassia amara L. (Simaroubaceae). Biol Pharm.Bull. 2002;25(9):1151-1155. .
  15. Vigneron M, Deparis X, Deharo E, et al. Antimalarial remedies in French Guiana: a knowledge attitudes and practices study. J Ethnopharmacol 4-26-2005;98(3):351-360. .

Copyright © 2011 Natural Standard (

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.

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