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What Is Quassia?

Quassia is a name used for several bitter-tasting plants, particularly Quassia amara, a tropical species in the Simaroubaceae family. Its wood and bark contain bitter compounds and have a history of use in traditional herbal preparations. Quassia has been used as a digestive bitter and in folk remedies for intestinal parasites and head lice. These traditional uses do not establish that quassia is safe or clinically effective for treating those conditions. Quassia is not an FDA-approved prescription medication, and botanical products sold under this name can differ in species, ingredients, and concentration.

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What Is Quassia?

Quassia is a name used for several bitter-tasting plants, particularly Quassia amara, a tropical species in the Simaroubaceae family. Its wood and bark contain bitter compounds and have a history of use in traditional herbal preparations. Quassia has been used as a digestive bitter and in folk remedies for intestinal parasites and head lice. These traditional uses do not establish that quassia is safe or clinically effective for treating those conditions. Quassia is not an FDA-approved prescription medication, and botanical products sold under this name can differ in species, ingredients, and concentration.

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How Does Quassia Work?

Quassia contains bitter plant compounds, including quassinoids, that account for much of its characteristic taste and biological activity. Researchers have studied certain quassinoids for effects on parasites, insects, and cellular processes in laboratory experiments. Bitter compounds may also stimulate sensory pathways associated with digestive secretions, although meaningful clinical benefits from quassia preparations have not been established. Laboratory findings cannot be assumed to demonstrate effectiveness in humans. The composition and biological activity of quassia products depend on the plant species, part used, extraction method, and concentration.

What Is Quassia Traditionally Used For?

Quassia has traditionally been used in herbal preparations intended to stimulate appetite, address digestive complaints, and manage certain intestinal parasites. Preparations from bitterwood have also been investigated for external uses, including head lice control. Human clinical evidence supporting these applications remains limited, and quassia should not replace established treatments for parasitic infections, persistent gastrointestinal symptoms, or other diagnosed conditions. Some plants referred to as quassia belong to different species, making product identification important. A healthcare professional can assess whether symptoms require testing or an approved medical treatment.

How Is Quassia Used?

Quassia has historically been prepared from dried wood or bark as an infusion, decoction, tincture, or other botanical extract. Commercial herbal products may contain different concentrations and may not identify the precise plant species. There is no FDA-approved medical dosing schedule for quassia and no well-established therapeutic dose supported by modern clinical trials. Consumers should not assume that a traditional preparation is safe for regular or prolonged use. People considering quassia should review the product's ingredients and discuss potential risks with a healthcare professional, particularly if they take prescription medications or have an existing medical condition.

What Are the Side Effects and Warnings of Quassia?

Quassia can irritate the gastrointestinal tract, particularly when consumed in large quantities, and may cause nausea, abdominal discomfort, or vomiting. Reliable information about the safety of concentrated extracts and prolonged use in humans is limited. Botanical safety references advise avoiding quassia during pregnancy unless a qualified healthcare professional directs its use. Potential reproductive effects have also raised concerns in experimental research, but their relevance to humans remains uncertain. Children and people who are breastfeeding should not use concentrated quassia preparations without medical advice. Severe vomiting, allergic symptoms, or persistent abdominal pain warrants medical assessment.

Common Questions About Quassia

Is quassia an FDA-approved medication?

No. Quassia is a botanical ingredient rather than an FDA-approved prescription treatment. Traditional medicinal use does not establish clinical effectiveness.

What plant does quassia come from?

The name commonly refers to Quassia amara, although other species, including Picrasma excelsa, are also known as quassia or bitterwood.

Can quassia treat intestinal parasites?

Quassia has a history of traditional use against parasites, but reliable human clinical evidence is insufficient to recommend it instead of approved antiparasitic treatment.

Is quassia safe during pregnancy?

Safety during pregnancy has not been established, and botanical safety references recommend avoiding quassia unless directed by a qualified healthcare professional.

References

Plant Name Details for Quassia amara. Royal Botanic Gardens, Kew. https://mpns.science.kew.org/mpns-portal/plantDetail?dbs=wcsCmp&plantId=2868415. Date Accessed November 3, 2026.

Quassia amara L. Plants of the World Online. https://powo.science.kew.org/taxon/814006-1. Date Accessed November 3, 2026.

Quassia: Uses, Side Effects, Dosage and Interactions. HelloPharmacist. https://hellopharmacist.com/drug-supplement-interactions/herbals/quassia. Date Accessed November 3, 2026.

Quassinoid Constituents of Quassia amara L. Leaf Herbal Tea: Impact on Its Antimalarial Activity and Cytotoxicity. Journal of Ethnopharmacology. https://pubmed.ncbi.nlm.nih.gov/19665539/. Date Accessed November 3, 2026.

Quassin. PubChem. https://pubchem.ncbi.nlm.nih.gov/compound/Quassin. Date Accessed November 3, 2026.