Does pau d'arco work against fungal infections and inflammation?

The medicinal activity of pau d'arco stems primarily from two naphthoquinone compounds: lapachol and beta-lapachone. These molecules disrupt the energy production of fungi, bacteria, and some viruses by interfering with their electron transport chains — in essence, cutting off their ability to generate cellular fuel².

Antifungal and Antimicrobial Effects

Laboratory studies show lapachol and beta-lapachone exhibit antifungal activity against Candida albicans, Aspergillus species, and other pathogenic fungi, with potency comparable to pharmaceutical antifungals in some in vitro models⁴. The inner bark also contains additional compounds — including furanonaphthoquinones and iridoids — that selectively inhibit harmful intestinal bacteria while appearing less disruptive to beneficial flora⁴.

Anti-inflammatory Action

A 2021 study published in Scientific Reports tested pau d'arco extracts directly on primary human lymphocytes — immune cells taken from real people, not a cell line. Different bark extracts significantly reduced levels of pro-inflammatory cytokines including IL-1β, IL-6, and TNF-α, with some extracts outperforming a pharmaceutical positive control³. This is meaningful: many plant anti-inflammatories only show activity in animal or test-tube models; this study used human immune cells.

The anti-inflammatory mechanism appears to involve suppression of NF-κB signaling — the same inflammatory pathway targeted by many anti-inflammatory drugs — along with modulation of COX enzyme activity².

Beta-Lapachone and Cancer Research

Beta-lapachone has attracted significant interest as a potential anti-cancer compound because it selectively targets cancer cells that overexpress an enzyme called NQO1 (NAD(P)H quinone oxidoreductase 1). Many solid tumors — including pancreatic, lung, and liver cancers — express NQO1 at much higher levels than normal tissue. Beta-lapachone exploits this by undergoing a futile redox cycle inside NQO1-rich cancer cells, generating oxidative stress that triggers cell death while leaving normal cells largely unharmed⁵. A pharmaceutical derivative (ARQ761) has reached early clinical trials, though pau d'arco itself has not been formally studied as a cancer treatment in humans.

Metabolic Effects

Animal research shows that lapacho tea extract inhibits pancreatic lipase, the enzyme responsible for fat digestion, and measurably delays the postprandial rise in blood triglycerides after a fatty meal⁵. The researchers used the weight-loss drug orlistat as a comparator in the same experiment, and the effect of pau d'arco extract has not been studied in clinical trials.

Practical Use and Dosage

Pau d'arco is most commonly consumed as a tea made from the inner bark (not the outer bark, which contains less active compound). A typical preparation uses 1–2 teaspoons of dried inner bark simmered in water for 15–20 minutes.

Traditional forms:

• Bark tea (most common, gentlest)
• Tincture or liquid extract (more concentrated)
• Capsules of powdered bark

General use notes:

• Typical tea doses: 2–3 cups per day during active use
• Most herbalists recommend limiting continuous use to 4–8 weeks, then taking a break
• Standardized extracts should specify lapachol content

Safety: Lapachol at high doses has blood-thinning effects and can interfere with vitamin K. At normal tea or supplement doses these effects are generally modest, but people taking anticoagulants (warfarin, heparin) or with bleeding disorders should avoid it. High supplemental doses have caused nausea and anemia in some people¹.

See our cat's claw page for another South American bark medicine with complementary anti-inflammatory properties. For gut-focused antimicrobial support, see our oregano oil page.

Ethnopharmacological Foundation

Gómez Castellanos et al. (2009) conducted a systematic review of pau d'arco's global ethnobotanical record, tracing documented traditional use across South American indigenous cultures — particularly among the Quechua — as well as its spread into European herbal medicine markets [PMID 18992801]. The review documented use for: fungal infections, inflammatory conditions, fever, malaria, and gastrointestinal complaints. The authors noted pau d'arco had become one of the more commercially traded Amazonian botanicals globally, yet formal clinical evidence lagged far behind traditional use claims.

Phytochemical Profile and Mechanistic Research

Zhang et al. (2020) published a comprehensive review of T. impetiginosa's traditional uses, phytochemistry, and immunopharmacological properties [PMID 32962180]. Key findings:

• Traditional uses include treating fever, malaria, bacterial and fungal infections, and skin diseases
• Phytochemicals and extracts isolated from T. impetiginosa have displayed pharmacological activities in various models
• Immunopharmacological activity includes anti-inflammatory, anti-allergic, anti-autoimmune, and anti-cancer properties, with a particularly strong effect on inflammation
• The anti-inflammatory mechanism is described through the target pathway by which T. impetiginosa inhibits the inflammatory response

The authors highlighted the need for further investigation to identify other pharmacological activities and the exact target proteins, and noted that further scientific evidence is required for clinical trials on its immunopharmacological effects and safety.

Human Immune Cell Study (2021)

The 2021 Scientific Reports study by Ryan et al. is among the most clinically relevant to date [PMID 33750911]. The researchers prepared multiple extracts from T. impetiginosa bark using different solvents (water, ethanol, methanol) and tested each on primary human lymphocytes — peripheral blood cells taken directly from healthy volunteers.

Results:

• All extracts were non-cytotoxic at the concentrations tested
• Multiple extracts significantly reduced TNF-α, IL-1β, IL-6, and IL-12 production
• Some extracts showed anti-inflammatory potency comparable to or exceeding celecoxib (a pharmaceutical COX-2 inhibitor) used as a positive control
• Different extraction methods yielded distinct cytokine profiles, suggesting the anti-inflammatory activity is not from a single compound but from a combination

The study noted that aqueous extracts (closest to traditional tea preparation) retained substantial anti-inflammatory activity, supporting the traditional method of preparation.

Antimicrobial Selectivity

Park et al. (2005) examined specific compounds isolated from T. impetiginosa inner bark for their effects on 18 human intestinal bacterial strains [PMID 15713033]. Using minimum inhibitory concentration (MIC) assays:

• The bark compounds selectively inhibited pathogenic species including Clostridium perfringens, Staphylococcus aureus, and Bacillus cereus
• Beneficial Lactobacillus species showed substantially higher resistance, suggesting some degree of selectivity for harmful over beneficial gut bacteria
• Activity was attributed primarily to lapachol and related naphthoquinones

These findings are consistent with the traditional use of pau d'arco for intestinal infections, though human studies have not been conducted.

Lipid Metabolism

Kiage-Mokua et al. (2012) tested lapacho tea extract in rats fed a fatty meal [PMID 22431070]. Their earlier work had indicated that ethanolic extracts of T. impetiginosa and several other plants inhibit pancreatic lipase in vitro; in this follow-up study the extracts, orlistat, or ethanol alone were given orally to the rats together with the test meal, and the rise in postprandial plasma triglycerides was followed over 4 hours. Of all the extracts, the bark of T. impetiginosa led to a significant delay in the postprandial increase of plasma triglycerides. Lapachol, which is contained in the bark, had no lipase-inhibitory effect in vitro, so it did not seem to mediate the effect.

Strength of Evidence Summary

Area	Evidence Level	Notes
Anti-inflammatory	Moderate	Strong mechanistic data; 2021 study used primary human cells
Antimicrobial (in vitro)	Moderate	Consistent across multiple labs; no human trials
Antifungal	Preclinical only	Lab activity demonstrated; no clinical trials
Cancer (beta-lapachone)	Early clinical	Pharmaceutical derivative ARQ761 in Phase I/II trials
Metabolic/lipid effects	Preclinical	Animal data only

Pau d'arco is not a replacement for pharmaceutical treatment of serious infections or cancer. The most defensible uses are as a supportive herb for inflammatory conditions and mild antimicrobial support, used traditionally and with reasonable modern mechanistic rationale. Anyone with serious immune compromise or taking anticoagulants should consult a clinician before use.