Pau d'Arco refers to the dried inner bark of Tabebuia impetiginosa (synonym: Handroanthus impetiginosus), a large flowering tree found throughout Central and South America, particularly in Brazil, Argentina, and Paraguay. Indigenous peoples of the Amazon and Inca regions have used it medicinally for centuries, particularly for infections, fevers, and inflammation. The bark is harvested, dried, and prepared as a decoction, tincture, or powdered supplement.

The primary bioactive compounds in Pau d'Arco are naphthoquinones, most notably lapachol and beta-lapachone. These compounds have demonstrated antifungal activity in laboratory settings by disrupting fungal cell membrane integrity and electron transport chains. Beta-lapachone in particular has been studied for its ability to interact with NAD(P)H quinone oxidoreductase (NQO1), an enzyme involved in oxidative stress regulation, which underlies both its potential anti-infective and anti-inflammatory properties.

Traditional preparation involves simmering the dried inner bark for 15–20 minutes to make a tea, which is the form with the longest historical record. Capsules and tablets typically contain standardized or unstandardized bark powder or extract. Tinctures use alcohol extraction and may concentrate certain constituents differently than aqueous decoctions. Standardization for lapachol content is not universally practiced, making product potency variable across brands.

• Candida/Fungal Infections
• Immune Support
• Inflammatory Conditions
• Bacterial Infections (adjunctive/topical)

• Nausea and vomiting (dose-dependent; more common at higher doses)
• Diarrhea or loose stools
• Anticoagulant effect / increased bleeding time (established for lapachol; dose-dependent)
• Dizziness
• Anemia (at high/sustained doses, based on NCI lapachol trial data)
• Potential liver stress at high doses or with prolonged use
• Contraindicated in pregnancy (potential uterotonic/abortifacient effects based on traditional use and animal data)

• Recommended daily: Traditional tea: 20–30g dried bark simmered in 1 liter of water, consumed throughout the day (approximately 2–3 cups). Capsule/extract: manufacturers typically recommend 500–1000mg standardized bark extract 2–3 times daily. No human RCT-validated therapeutic dose exists; these are convention-based ranges only.
• Best time of day: No evidence-based guidance; traditionally taken as a tea spread throughout the day rather than in a single large dose.
• With or without food: Taking with food is recommended to reduce gastrointestinal side effects such as nausea.
• Time to effect: Traditional use suggests 2–6 weeks of consistent use for observable effects; no controlled human data define an onset window.
• How long to take it: Typically used for 4–8 week courses in traditional herbal medicine, followed by a break. Long-term continuous use is not supported by safety data and is not recommended. Avoid in pregnancy at any duration.