Limited evidenceImmunity

Pau d'Arco

South American bark containing lapachol and beta-lapachone. Active against microbes and cancer cells in the laboratory, but the human evidence is one small supportive-care study, and the active compounds were toxic at therapeutic doses in cancer trials.

Evidence last reviewed: August 2026

What the science says

Antimicrobial and anti-inflammatory activity in the laboratory Limited evidence
Beta-lapachone shows anti-inflammatory activity in cell and animal models and synergy with conventional antibiotics against methicillin-resistant Staphylococcus aureus in vitro. There is no controlled human trial of pau d'arco for candida or any infection.
Oral mucositis during radiotherapy Limited evidence
A phase II study of a lapacho-based oral preparation in head and neck cancer patients described it as feasible and safe for reducing radiotherapy-induced mucositis. It was uncontrolled and small, so it cannot show efficacy.
Anticancer claims Limited evidence
Lapachol and lapachone analogues have been extensively patented and studied against tumour cells, but early clinical work with lapachol was halted because doses needed for an antitumour effect caused unacceptable toxicity, including anaemia and prolonged clotting times.

Dosage & safety

Studied doseTraditional preparation is a decoction of 1–2 g of inner bark simmered and taken up to three times daily; capsules commonly give 500–1,000 mg. No dose has been validated in controlled human research, and lapachol content in commercial bark varies enormously.

SafetyAt higher doses lapachol causes nausea, vomiting, anaemia and vitamin K antagonism with increased bleeding — do not combine with warfarin or other anticoagulants. Avoid in pregnancy, where animal data show reproductive toxicity, and in breastfeeding and children. Product identity is a real problem: bark sold as pau d'arco often comes from several Handroanthus or Tabebuia species with different constituents. Suspected candida or recurrent infections deserve a proper diagnosis.

Scientific references

Oral Lapacho-Based Medication: An Easy, Safe, and Feasible Support to Prevent and/or Reduce Oral Mucositis During Radiotherapy for Head and Neck Cancer
Giacomelli I, Scartoni D, Fiammetta M — Nutr Cancer, 2015
An evaluation on potential anti-inflammatory effects of β-lapachone
Mokarizadeh N, Karimi P, Kazemzadeh H — Int Immunopharmacol, 2020
Lapachol and lapachone analogs: a journey of two decades of patent research(1997-2016)
Hussain H, Green IR — Expert Opin Ther Pat, 2017

Where to buy

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