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Tabebuia Impetiginosa (Lapacho)
A South American tree bark traditionally brewed as a tea for immune support and infections. Its naphthoquinones (lapachol, beta-lapachone) show antimicrobial and anti-inflammatory activity in cell and animal studies — but human efficacy data are essentially absent, and lapachol carries real toxicity at higher doses (anticoagulant, GI).
What the evidence says
Most Pau D'Arco studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from medium-quality studies published 1976–2021.
Based on 5 studies
Confidence
Low confidenceScores very low because every efficacy signal is preclinical (in-vitro and rodent), there are no controlled human trials, and its active lapachol carries documented anticoagulant and GI toxicity.
No trials currently enrolling · 2 completed on ClinicalTrials.gov
Registered trials show research momentum for Pau D'Arco, not proof of effect — a registration is a plan, and posted results are sponsor-reported, not peer-reviewed. They are never counted toward the evidence rating above.
Browse these trials on ClinicalTrials.govClinicalTrials.gov · as of Oct 2026
Pau d'arco is the inner bark of South American Tabebuia (Handroanthus) trees, long used in folk medicine as a tea for infections, inflammation, and 'immune' complaints.
Its rationale rests on naphthoquinones — chiefly lapachol and beta-lapachone — which show antibacterial, antifungal, antiparasitic, anti-inflammatory, and antitumor activity in test-tube and rodent models. The honest reality: nearly all of this evidence is preclinical (in-vitro and animal).
There are essentially no controlled human trials demonstrating that pau d'arco supplements improve immunity or treat infection in people.
Equally important, lapachol is not benign: clinical antitumor evaluations in the 1970s found dose-limiting toxicity, including anticoagulant effects (prothrombin prolongation) and gastrointestinal upset.
This is a traditional remedy with an interesting preclinical chemistry but unproven clinical benefit and a genuine safety ceiling.
Lapachol and beta-lapachone show antibacterial, antifungal, and antiparasitic activity in vitro — the basis of the traditional 'anti-infective' claim, but unproven in humans.
Bark extract suppressed NF-kB and AP-1 signaling and pro-inflammatory cytokines in rat and macrophage models.
How Pau D'Arco works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
Avoid — lapachol toxicity and lack of safety data.
Avoid — additive anticoagulant/bleeding risk.
Laboratory findings involving lapachol raise a possible bleeding concern; they do not establish the risk for every pau d’arco product. Tell the surgical and anaesthetic team the exact product, dose and last dose well before an operation. Follow their instructions about stopping and restarting it.
Lapachol has anticoagulant activity (prothrombin-prolonging) and may potentiate bleeding when combined with blood-thinning drugs.
High-dose naphthoquinone exposure may add to GI and metabolic burden; caution with polypharmacy.
Tip: Take with food; reduce dose
Tip: Avoid high doses; discontinue and seek care if bruising or bleeding occurs
Tip: Avoid high-dose extracts
The current evidence for Pau D'Arco is insufficient to assign an evidence score, based on 5 indexed studies. A South American tree bark traditionally brewed as a tea for immune support and infections. Its naphthoquinones (lapachol, beta-lapachone) show antimicrobial and anti-inflammatory activity in cell and animal studies — but human efficacy data are essentially absent, and lapachol carries real toxicity at higher doses (anticoagulant, GI). Representative study: PMID 29317792.
Dosing for Pau D'Arco: Traditionally 1-2g dried bark as tea, 1-3x daily (no validated efficacy dose) (no cited human trial states a dose). Individual needs vary — start at the lower end of the range and adjust based on how you respond.
The best time to take Pau D'Arco is with meals. Take it with food. Taken with food to reduce GI upset; no human-trial-validated dose exists and higher intakes raise toxicity risk.
Pau D'Arco should be used with caution — talk to a healthcare provider before taking it. Reported side effects include bleeding / bruising (dose-related, lapachol), vomiting at high doses, nausea / GI upset. How often they occur is not established for all of them. Use caution if any of these apply to you: Pregnancy and breastfeeding; Bleeding disorders or upcoming surgery; Concurrent anticoagulant/antiplatelet therapy.
Andrographis
Likely helpsStudied for comfort and symptom duration during upper-respiratory infections when taken at onset — also supports liver health.
Chlorella
Too few graded studiesFreshwater algae with the highest chlorophyll content of any plant — binds heavy metals and supports detoxification pathways.
Pelargonium Sidoides
Too few graded studiesA standardized root extract (EPs 7630) of the South African geranium, best evidenced for shortening symptom duration and severity in acute bronchitis and other upper-respiratory infections. The Cochrane review found the liquid preparation effective for acute bronchitis but rated overall evidence quality as low to very low.
Cranberry Extract
Mixed evidenceWell-researched extract that prevents UTI-causing bacteria from adhering to the urinary tract — best for prevention, not treatment.
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Reviewed by Dr. Baher Al Hakim · Last reviewed June 2026 · evidence from 5 studies · how we score · editorial policy
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
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