Skip to main content


Scientific Name(s): Picrasma excelsa, Quassia amara L.
Common Name(s): Amara species, Amargo, Bitter wood, Jamaican quassia, Picrasma, Ruda, Surinam quassia, Surinam wood

Medically reviewed by Last updated on Dec 21, 2021.

Clinical Overview


Quassia has a variety of suggested uses, including treatment for measles, diarrhea, fever, and lice. Quassia has antibacterial, antifungal, antifertility, antitumor, antileukemic, and insecticidal actions as well. However, efficacy in clinical trials has not been proven.


Quassia wood has been used as a bitter tonic, with a typical oral dose of 500 mg. No studies have been performed to support this dose. Several recent studies of topical quassia tincture for head lice have been reported.


Contraindications have not yet been identified.


Documented adverse reactions. Avoid use.


None well documented.

Adverse Reactions

Quassia is used in a number of food products and is considered safe by the FDA. If taken in large doses, this product can irritate the GI tract and cause vomiting. It is not recommended for pregnant women.


Quassia is listed as generally regarded as safe (GRAS) by the FDA. Parenteral administration of quassin is toxic, leading to cardiac irregularities, tremors, and paralysis.

Scientific Family

  • Simaroubaceae


Surinam quassia is a 2 to 5 m tall shrub or small tree native to Argentina, Colombia, Guyana, and Panama. Jamaican quassia is a taller tree that reaches 25 m and is native to the Caribbean Islands, Jamaica, West Indies, and northern Venezuela. The leaves and pale yellow wood are used medicinally.Duke 1985, Newall 1996, Schulz 1998, USDA 2017


Quassia has been used for malaria in the Amazon region. It has been used topically for measles and orally or rectally for intestinal parasites, diarrhea, and fever. The plants have been used as anthelmintics and insecticides. Central Americans have been known to build boxes out of quassia wood, which acts as a natural insect repellent, to store clothing.Duke 1985, Kupchan 1976, Schulz 1998

Quassia has been used as an insecticide. Traditional use includes remedies for infestations of lice or worms, anorexia, and dyspepsia.Duke 1985 Certain tribes have used the plants to treat measles and fever, and as a mouthwash.Branch 1983, Duke 1994, Evans 1991

The extracts and purified mixtures of bitter principles ("quassin") have been used to give a bitter taste to various food products, especially alcoholic (eg, bitters, liqueurs) and nonalcoholic beverages, desserts, candy, baked goods, and puddings.Garcia Gonzalez 1997


Both quassia species have similar constituents. These include alkaloids (0.25%), such as canthin-6-one, 5-methoxycanthin-6-one, and carboline alkaloids. Terpenoids in 1 or both plants include isoquassin and mixtures of bitter principles (said to be 50 times more bitter than quinine), including quassin, neo-quassin, and 18-hydroxyquassin. Dihydronorneoquassin and simalikalactone D are also present. Other constituents include coumarins (Q. amara), thiamine (P. excelsa), beta-sitosterol, and beta-sitostenone.Duke 1985, Kupchan 1976, Newall 1996, Schulz 1998 From Q. amara, the quassinoid quassimarin has been reportedCasinovi 1966 and amarid 18-oxyquaxine has been isolated.Fernando 1993 The molecular phylogenetics of Q. amara have been studied using the chloroplast gene rbcl.Rutter 1990

Uses and Pharmacology

Chemotherapeutic effects

Animal data

Quassimarin has been reported to have antileukemic properties when tested in animals. Antitumor activity in mice has been demonstrated, as well as in vitro activity of quassin against human nasopharynx carcinoma.(Duke 1985)

Head lice

Clinical data

Quassia, as a tincture, has reportedly been used successfully to treat head lice. Canthin-6-one possesses antibacterial and antifungal activity.(Duke 1985, Mac-Mary 2012)

Other uses

Research is ongoing, with evaluations for potential applications in malaria, diabetes, and ulcer healing.(Cosmetic 2008, Mishra 2010)

The beta-carboline alkaloids exhibit positive inotropic activity in animals.(Duke 1985)

A 4% hydroglycolic extract of Q. amara gel was reportedly effective in reducing the severity of symptoms in facial seborrheic dermatitis(Diehl 2013) and rosacea.(Ferrari 2012)

Quassin has demonstrated antilarval activity and was effective at concentrations of 6 ppm.(Evans 1992)

In a hepatotoxic mouse model, administration of Q. amara stem bark extract not only improved lipid parameters (ie, total cholesterol, low-density lipoprotein, high-density lipoprotein) but also improved oxidative stress markers (ie, melondialdehyde, superoxide dismutase).(Obembe 2021)


Quassia wood has been used as a bitter tonic, with a typical oral dose of 500 mg. No studies have been performed to support this dosage. Several recent studies of topical quassia tincture for head lice have been reported.

Pregnancy / Lactation

Documented adverse reactions. Avoid use.Bisset 1994


None well documented.

Adverse Reactions

No adverse reactions were reported upon topical application of the scalp preparation in the 454 patients in the head lice study.(Duke 1985) However, large amounts given orally have been known to irritate the mucus membrane in the stomach and may lead to vomiting.(Schulz 1998) Excessive use may also interfere with existing cardiac and anticoagulant regimens. Because of the plant's cytotoxic and emetic properties, its use during pregnancy should be avoided.(Duke 1985)

Histopathological and morphological deformities were observed in mouse spermatozoa induced by administration of Q. amara extract as well as its biologically active secondary metabolite, quassin.(Faisal 2021) A mechanism of this activity may be due to inhibition of cuticle development, as suggested in 1 report.(Njar 1995)


Quassia is listed as generally regarded as safe (GRAS) by the FDA. Parenteral administration of quassin is toxic, leading to cardiac irregularities, tremors, and paralysis.Schulz 1998

Mean weights of testes, seminal vesicles, and epididymides were significantly reduced, and weights of the anterior pituitary glands were significantly increased in rats given quassin at doses up to 2 g/kg in drinking water. Furthermore, lowered sperm counts, levels of LH, follicle-stimulating hormone (FSH) and of testosterone were observed.Garcia Gonzalez 1997, Mac-Mary 2012, Raji 1997



This information relates to an herbal, vitamin, mineral or other dietary supplement. This product has not been reviewed by the FDA to determine whether it is safe or effective and is not subject to the quality standards and safety information collection standards that are applicable to most prescription drugs. This information should not be used to decide whether or not to take this product. This information does not endorse this product as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this product. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this product. This information is not specific medical advice and does not replace information you receive from your health care provider. You should talk with your health care provider for complete information about the risks and benefits of using this product.

This product may adversely interact with certain health and medical conditions, other prescription and over-the-counter drugs, foods, or other dietary supplements. This product may be unsafe when used before surgery or other medical procedures. It is important to fully inform your doctor about the herbal, vitamins, mineral or any other supplements you are taking before any kind of surgery or medical procedure. With the exception of certain products that are generally recognized as safe in normal quantities, including use of folic acid and prenatal vitamins during pregnancy, this product has not been sufficiently studied to determine whether it is safe to use during pregnancy or nursing or by persons younger than 2 years of age.

Bisset NG, trans-ed. Herbal Drugs and Phytopharmaceuticals. Stuttgart: CRC Press, 1994;400-401.
Branch L, et al. Folk Medicine of Alter do Chao, Para, Brazil. Acta Amazonica. 1983;13:737–797.
Casinovi CG, Ceccherelli P, Grandolini G. A new amarid 18-oxyquaxine, isolated from Quassia amara [in Italian]. Ann Ist Super Sanita. 1966;2:414-416.4185462
Cosmetic Ingredient Review Expert Panel. Final report of the safety assessment of Alcohol Denat., including SD Alcohol 3-A, SD Alcohol 30, SD Alcohol 39, SD Alcohol 39-B, SD Alcohol 39-C, SD Alcohol 40, SD Alcohol 40-B, and SD Alcohol 40-C, and the denaturants, Quassin, Brucine Sulfate/Brucine, and Denatonium Benzoate. Int J Toxicol. 2008;27 Suppl 1:1-43. PMID: 18569160.
Diehl C, Ferrari A. Efficacy of topical 4% Quassia amara gel in facial seborrheic dermatitis:a randomized, double-blind, comparative study. J Drugs Dermatol. 2013 Mar;12(3):312-5. PMID: 23545914.23545914
Duke JA. CRC Handbook of Medicinal Herbs. Boca Raton, FL: CRC Press; 1985:399.
Duke JA, Vasquez R. Amazonian Ethnobotanical Dictionary. Boca Raton, FL: CRC Press, Inc.; 1994.
Evans DA, Kaleysa RR. Effect of quassin on the metabolism of catecholamines in different life cycle stages of Culex quinquefasciatus. Indian J Biochem Biosphys. 1992;29:360–363.1427964
Evans DA, Raj RK. Larvicidal efficacy of Quassin against Culex quinquefasciatus. Indian J Med Res. 1991;93:324-327.1778621
Faisal K, Akbarsha MA. Observations on Dag-like defect of spermatozoa induced by treatment of the phytotherapeutic Quassia amara/quassin in the mouse model. Andrologia. 2021;53(6):e14046.33756011
Fernando ES, Gadek PA, Crayn DM, Quinn CJ. Rosid affinities of Surianaceae: molecular evidence. Mol Phylogenet Evol. 1993;2:344-350.8049783
Ferrari A, Diehl C. Evaluation of the efficacy and tolerance of a topical gel with 4% quassia extract in the treatment of rosacea. J Clin Pharmacol. 2012 Jan;52(1):84-8. PMID: 21343346.21343346
Garcia Gonzalez M, Gonzalez Camacho SM, Pazos Sanou L. Pharmacologic activity of the aqueous wood extract from Quassia amara (Simarubaceae) on albino rats and mice [in Spanish]. Rev Biol Trop. 1997;44-45:47-50.9404515
Kupchan SM, Streelman DR. Quassimarin, a new antileukemic quassinoid from Quassia amara. J Org Chem. 1976;41:3481-3482.978297
Mac-Mary S, Messikh R, Jeudy A, et al. Assessment of the efficacy and safety of a new treatment for head lice. ISRN Dermatol. 2012;2012:460467. PMID: 2320992823209928
Mishra K, Chakraborty D, Pal A, Dey N. Plasmodium falciparum: in vitro interaction of quassin and neo-quassin with artesunate, a hemisuccinate derivative of artemisinin. Exp Parasitol. 2010 Apr;124(4):421-7. PMID: 2003665720036657
Newall CA, Anderson LA, Phillipson JD. Herbal Medicines: A Guide for Health-Care Professionals. London: Pharmaceutical Press; 1996:223-234.
Njar VC, Alao TO, Okogun JI, Raji Y, Bolarinwa AF, Nduka EU. Antifertility activity of Quassia amara: quassin inhibits the steroidogenesis in rat Leydig cells in vitro. Planta Med. 1995;61:180-182.7753928
Obembe OO, Usman TO, Raji Y. Hepatoprotective effects of Quassia amara stem bark against cadmium-induced toxicity in male Wistar rats [published online ahead of print, 2021 Feb 5]. J Basic Clin Physiol Pharmacol. 2021;10.1515/jbcpp-2020-0128.33544994
Quassia amara and Picrasma excelsa. USDA, NRCS. 2017. The PLANTS Database (, December 2017). National Plant Data Team, Greensboro, NC 27401-4901 USA. Accessed December 2017.
Raji Y, Bolarinwa AF. Antifertility activity of Quassia amara in male rats—in vivo study. Life Sci. 1997;61:1067-1074.9307052
Rutter R. Catalogo de Plantas Utiles de la Amazonia Peruana. Lima, Peru: Instituto Linguistico de Verano; 1990.
Schulz V, Tyler VE. Rational Phytotherapy: A Physician's Guide to Herbal Medicine. Berlin: Springer; 1998:171.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.