Herb & supplement monograph

Pau D'arco Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by ·Updated July 2026
What is this page for?

First and foremost: how Pau D'arco interacts with medications. The heart of this page is the interaction list — every drug Pau D'arco is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Pau D'arco is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Pau D'arco Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Pau D'arco drug interaction appears low for most people, unless you take a medication that affects blood clotting. None of the listed interactions are rated major, and all of them trace back to a single bleeding-related concern supported mostly by lab research rather than human studies.

Interactions deserving the most attention

The one area that deserves real attention is anticoagulant and antiplatelet drugs, often called blood thinners. Lab studies suggest pau d'arco may make platelets less sticky and may interfere with vitamin K, which the body uses in clotting. One human study also found that high doses of lapachol, a compound in pau d'arco, raised bleeding risk. Because bleeding is a serious outcome, we treat this combination cautiously even though the evidence for the whole herb is not settled.

What the rest of the list means

The long list of interacting medications looks intimidating, but it largely reflects this single theoretical bleeding concern applied across many drugs. Whether whole pau d'arco causes meaningful bleeding problems in people has not been clearly shown, so for most other medicines no documented interaction exists.

Check your medications against Pau D'arco

Based on HelloPharmacist’s Pau D'arco interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Pau D'arco

122 medications have a known interaction with Pau D'arco, graded by severity. Select any drug for the full evidence-based detail.

2,830 drugs
AbciximabReoPro› AbrocitinibCibinqo› AcenocoumarolSintrom› Acetaminophen, AspirinGemnisyn› Acetaminophen, Aspirin, CaffeineExcedrin, Excedrin Extra Strength, Excedrin Migraine› Acetaminophen, IbuprofenCombogesic› Acetylsalicylic AcidEntrophen› Alteplase, TpaActilyse, Activase› Aluminum Hydroxide, Aspirin, Codeine Phosphate, Magnesium HydroxideAscriptin Codeine #2› Aluminum Hydroxide, Aspirin, Magnesium HydroxideAscriptin› Anacaulase-bcdbNexoBrid› AnagrelideAgrylin› AnisindioneMiradon› Antithrombin IiiThrombate III› ApixabanEliquis› ArgatrobanArgatroban› AspirinAngettes 75, ASA, Asaphen, Aspirin, Caprin, Cartia +8 more› Aspirin, Aluminum Hydroxide, Codeine Phosphate, Magnesium HydroxideAscriptin Codeine #3› Aspirin, ButalbitalAxotal› Aspirin, Butalbital, CaffeineFiorinal› Aspirin, Butalbital, Caffeine, Codeine PhosphateFiorinal w/ Codeine› Aspirin, Butalbital, Caffeine, PhenacetinMarnal› Aspirin, CaffeineAnacin› Aspirin, Caffeine, Codeine PhosphateAnacin w/ Codeine› Aspirin, Caffeine, Dihydrocodeine BitartrateSynalgos DC› Aspirin, Caffeine, Dover's PwdAcedoval, Dovacet› Aspirin, Caffeine, HydrocodoneDamason-P› Aspirin, Caffeine, Isobutylallylbarbituric Acid, PhenacetinLanorinal› Aspirin, Caffeine, OrphenadrineInvagesic, Invagesic Forte, Norgesic, Norgesic Forte, Orphengesic, Orphengesic Forte› Aspirin, Caffeine, Phenacetin, PropoxypheneMargesic Comp. 65›
Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

  • Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
  • Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
  • Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
  • No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

  • Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
  • Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
  • Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

  • Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
  • Each drug listed above links to the full report for that exact Pau D'arco combination — clinical detail, likelihood, evidence level, and citations.
  • Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.
The big picture

The kinds of drugs Pau D'arco affects

Every type of medication (drug category) Pau D'arco is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 1 drug category Pau D'arco interacts with
Anticoagulant/antiplatelet Drugs
Anticoagulant/Antiplatelet Drugs

Theoretically, pau d'arco might increase the risk of bleeding when taken with anticoagulant or antiplatelet drugs.
In vitro research shows that pau d'arco reduces platelet aggregation and may interfere with vitamin K. One clinical study shows that taking the lapachol constituent of pau d'arco in doses above 1.5 grams daily increases the risk of bleeding. The effects of whole pau d'arco or pau d'arco extract in humans are unclear.

Likelihood Possible Evidence D
Monograph

Pau D'arco: Uses, Safety & Side Effects

Medically reviewed by · Reviewed July 2026 ·
The bottom line

Pau d'arco is a South American tree bark traditionally used for infections and inflammation, and it contains compounds like lapachol that show activity in lab studies. However, strong human evidence is lacking, and safety concerns exist at higher doses, so it should be used cautiously and discussed with a pharmacist or doctor first.

Pau D'arco
Scientific name
Handroanthus impetiginosus
Family
Bignoniaceae
Part used
Inner bark
Common forms
Tea (decoction), capsules, tablets, liquid extracts, tinctures
People commonly use it for
  • Infections (bacterial, fungal, yeast)
  • Inflammation
  • Immune support
  • Digestive complaints
  • Skin conditions

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance
OverallUse caution

May cause side effects at higher doses and human safety data is limited.

PregnancyPossibly Unsafe

When used orally in typical doses. Animal studies have found that lapachol, a constituent of pau d'arco, has teratogenic and abortifacient effects; av...

Read the full pregnancy detail
BreastfeedingInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

Pau d'arco is a supplement made from the inner bark of large evergreen trees that grow in the Amazon rainforest and other tropical parts of South and Central America. The name is Portuguese for "bow tree," because the hard wood was traditionally used to make hunting bows.

For generations, people in South America have used pau d'arco bark in traditional medicine, often brewed as a tea. Today it is sold around the world as a tea, in capsules and tablets, and as liquid extracts or tinctures. People take it most often for infections, inflammation, and general "immune support."

How it works

Pau d'arco bark contains naturally occurring compounds called naphthoquinones, the best known being lapachol and beta-lapachone. In laboratory studies, these compounds have shown the ability to slow the growth of certain bacteria, fungi, and yeast, and to reduce markers of inflammation.

Researchers think these effects may come from the compounds interfering with the energy and growth processes of microbes and cells, and from antioxidant activity that helps protect cells from damage. However, these mechanisms are mostly based on test-tube and animal research, and it is not clear whether a person who drinks the tea or takes a capsule absorbs enough of these compounds to produce a meaningful effect.

Effectiveness

Does Pau D'arco work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by .

Evidence overview · 4 uses evaluated
4 Insufficient evidence
How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.
2Likely EffectiveGood evidence, though not yet conclusive.
3Possibly EffectiveSome evidence suggests a benefit.
4Possibly IneffectiveSome evidence it may not help.
5Likely IneffectiveFairly strong evidence it doesn’t help.
6IneffectiveStrong evidence it doesn’t work.
7Insufficient Reliable Evidence to RateToo little research to say either way.

For Pau D'arco, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.

Also studied for 4 conditions — evidence insufficient to rate
Insufficient Reliable Evidence To Rate Cancer
Rating & evidence shown verbatim from Natural Medicines

Although there has been interest in using oral pau d'arco for cancer, there is insufficient reliable information about the clinical effects of pau d'arco for this purpose.

Insufficient Reliable Evidence To Rate Dysmenorrhea
Rating & evidence shown verbatim from Natural Medicines

Oral pau d'arco has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Peptic ulcers
Rating & evidence shown verbatim from Natural Medicines

Although there has been interest in using oral pau d'arco for peptic ulcers, there is insufficient reliable information about the clinical effects of pau d'arco for this purpose.

Insufficient Reliable Evidence To Rate Wound healing
Rating & evidence shown verbatim from Natural Medicines

Although there has been interest in using oral and topical pau d'arco for wound healing, there is insufficient reliable information about the clinical effects of pau d'arco for this purpose.

Source & disclaimer. Effectiveness ratings and evidence summaries are provided by Natural Medicines (Therapeutic Research Center) and shown as licensed. Where Natural Medicines hasn’t rated a use, HelloPharmacist’s pharmacists may add their own reviewed rating and evidence (each such entry is labeled). This is educational information, not medical advice — talk with your pharmacist or doctor before starting, stopping, or changing a supplement.

Safety & precautions

Pau d'arco appears to be reasonably tolerated when taken in small amounts for a short time, such as the traditional tea. However, higher doses can be toxic. Older research using larger amounts of lapachol reported problems such as nausea, vomiting, and effects on blood clotting that may raise the risk of bleeding.

People with bleeding disorders, or who are scheduled for surgery, should be especially careful and talk with a healthcare provider before use. Because the long-term safety of regular use is not well studied, it is wise to avoid taking large amounts or using it for long periods.

Pregnancy and breastfeeding: Pau d'arco should be avoided during pregnancy because of concerns it could harm the developing baby, and there is not enough safety information for use while breastfeeding. If you are pregnant, trying to become pregnant, or nursing, do not use it.

Always check with a pharmacist or doctor before starting pau d'arco, especially if you have a medical condition or take other medicines.

Side effects

At lower amounts, side effects are usually mild and may include nausea or stomach upset. At higher doses, pau d'arco can cause more serious problems, including nausea, vomiting, dizziness, and an increased risk of bleeding because of its possible effect on blood clotting.

Stop using it and seek medical care if you notice unusual bruising or bleeding, severe stomach upset, or any allergic reaction such as rash, itching, swelling, or trouble breathing.

Pau D'arco: Reported Adverse Effects

Documented safety reports on Pau D'arco from the evidence-graded Natural Medicines (TRC Healthcare) database, shown word-for-word from the licensed record.

Reports by condition
Anemia Hematologic

Orally, the lapachol constituent of pau d'arco, taken in doses above 1.5 grams daily, may cause anemia and increased risk of bleeding.

  1. Block JB, Serpick AA, Miller W, Wiernik PH. Early clinical studies with lapachol (NSC-11905). Cancer Chemother Rep 2. 1974;4(4):27-8.
Asthma Immunologic

Occupational exposure to sawdust from the pau d'arco tree and related species may cause asthma and dermatitis. The fresh sawdust can produce erythema and papules which progress to a severe weeping and crusting dermatitis.

  1. Algranti E, Mendonça EM, Ali SA, Kokron CM, Raile V. Occupational asthma caused by Ipe (Tabebuia spp) dust. J Investig Allergol Clin Immunol 2005;15(1):81-3.
Diarrhea Gastrointestinal

Orally, the lapachol constituent of pau d'arco, taken in doses above 1.5 grams daily, may cause severe nausea, vomiting, and diarrhea.

  1. Block JB, Serpick AA, Miller W, Wiernik PH. Early clinical studies with lapachol (NSC-11905). Cancer Chemother Rep 2. 1974;4(4):27-8.
Vertigo Neurologic/CNS

Orally, the lapachol constituent of pau d'arco, taken in doses above 1.5 grams daily, may cause dizziness.

  1. Block JB, Serpick AA, Miller W, Wiernik PH. Early clinical studies with lapachol (NSC-11905). Cancer Chemother Rep 2. 1974;4(4):27-8.
DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

Adverse-effects data: Natural Medicines, Therapeutic Research Center

Dosing

There is no well-established, standardized dose for pau d'arco. Products vary widely in strength and form, and the amount of active compounds can differ from one product to another.

Because larger doses raise the risk of toxic effects, it is best to use the smallest reasonable amount, follow the directions on the product label, and not exceed them. Talk with a pharmacist or doctor before starting so they can help you decide whether it is appropriate and review your other medicines and health conditions.

Pregnancy & Breastfeeding

Pau D'arco & Pregnancy

Possibly Unsafe

When used orally in typical doses. Animal studies have found that lapachol, a constituent of pau d'arco, has teratogenic and abortifacient effects; avoid using. There is insufficient reliable information available about the safety of pau d'arco when used topically in pregnancy; avoid using.

  1. Guerra, Mde O., Mazoni, A. S., Brandao, M. A., and Peters, V. M. Toxicology of Lapachol in rats: embryolethality. Braz.J Biol. 2001;61(1):171-174.
  2. Felicio, A. C., Chang, C. V., Brandao, M. A., Peters, V. M., and Guerra, Mde O. Fetal growth in rats treated with lapachol. Contraception 2002;66(4):289-293.

Pau D'arco & Breastfeeding

Insufficient reliable information

Insufficient reliable information available; avoid using.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

© 2026 Therapeutic Research Center

Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center

References & further reading

The 6 references that drive our Pau D'arco monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Gómez Castellanos JR, Prieto JM, Heinrich M. Red Lapacho (Tabebuia impetiginosa)--a global ethnopharmacological commodity? J Ethnopharmacol 2009;121:1-13. PubMed
  2. Guerra, Mde O., Mazoni, A. S., Brandao, M. A., and Peters, V. M. Toxicology of Lapachol in rats: embryolethality. Braz.J Biol. 2001;61(1):171-174. PubMed
  3. Felicio, A. C., Chang, C. V., Brandao, M. A., Peters, V. M., and Guerra, Mde O. Fetal growth in rats treated with lapachol. Contraception 2002;66(4):289-293. PubMed
  4. Son, D. J., Lim, Y., Park, Y. H., Chang, S. K., Yun, Y. P., Hong, J. T., Takeoka, G. R., Lee, K. G., Lee, S. E., Kim, M. R., Kim, J. H., and Park, B. S. Inhibitory effects of Tabebuia impetiginosa inner bark extract on platelet aggregation and vascular s
  5. Block JB, Serpick AA, Miller W, Wiernik PH. Early clinical studies with lapachol (NSC-11905). Cancer Chemother Rep 2. 1974;4(4):27-8.
  6. Algranti E, Mendonça EM, Ali SA, Kokron CM, Raile V. Occupational asthma caused by Ipe (Tabebuia spp) dust. J Investig Allergol Clin Immunol 2005;15(1):81-3.
Keep reading

This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Brand directory

Brands that make products with Pau D'arco

195 brands in our database make a supplement containing Pau D'arco.

Product directory

Supplement products with Pau D'arco

721 products in our database contain Pau D'arco. Open any to see its full ingredient list and every drug interaction we check.

Green 33 by 4 Organics Tablet Or Pill 90 Vegetarian Tablet(s) View ingredients & interactions Green Power by Greens Today Powder 13.33 oz. · 375 Gram(s) View ingredients & interactions Greens Berry by It Works! Powder 4.5 oz. · 127.5 Gram(s) View ingredients & interactions Greens on the Go Berry by It Works! Powder 30 Single Serve Packet(s) · 4.5 oz. · 127.5 Gram(s) View ingredients & interactions Herbal Actives Pau D'Arco 100 MG/3% Naphthoquinones by Nature's Plus Capsule 60 Vegetarian Capsule(s) View ingredients & interactions Herbal Aloe Force by Herbal Answers Liquid 32 fl. Oz. · 946 mL View ingredients & interactions Herbal Immune Support Formula by Royal Guard Capsule 30 Individual Pack(s) View ingredients & interactions Histacom by Energique Liquid 2 Fluid Ounce(s) · 59 mL View ingredients & interactions Honokare by Get Healthy Again Liquid 2 fl. Oz. · 59 mL View ingredients & interactions Immu Cell by Professional Botanicals Capsule 60 Veg. Capsule(s) View ingredients & interactions Immu Guard by Professional Botanicals Capsule 30 Packet(s) View ingredients & interactions Immu Guard by Professional Botanicals Capsule 90 Veg. Capsule(s) View ingredients & interactions Immunace by NaturesPlus Tablet Or Pill 90 Tablet(s) View ingredients & interactions Immunagen by Earth Friend Herb Co. Liquid 4 Fluid Ounce(s) · 120 mL View ingredients & interactions Immunagen by Earth Friend Herb Co. Liquid 1 Fluid Ounce · 30 mL View ingredients & interactions Immune Action by NaturesPlus Capsule 120 Vegetarian Capsule(s) View ingredients & interactions Immune Action by NaturesPlus Capsule 120 Capsule(s) View ingredients & interactions Immune AV by TransFormation Professional Protocol Capsule 60 Capsule(s) View ingredients & interactions Immune BAB by Microbe Formulas Liquid 4 Fluid Ounce(s) · 120 mL View ingredients & interactions Immune Bloom+ by Catie's Powder 75 Gram(s) · 2.65 Oz(s) View ingredients & interactions Immune Boost by Microbe Formulas Liquid 4 Fluid Ounce(s) · 120 mL View ingredients & interactions Immune Borr by Microbe Formulas Liquid 4 Fluid Ounce(s) · 120 mL View ingredients & interactions Immune Factors 2000 mg by Remedys Nutrition Capsule 60 Vcap(s) View ingredients & interactions Immune Support by Crystal Star Liquid 1 Fluid Ounce(s) · 30 mL View ingredients & interactions
Pharmacist Counseling Corner

Pau D'arco: Common Questions

What is Pau D'arco used for, and does it work?
People use Pau D'arco for a range of reasons, but according to the Natural Medicines database the current clinical evidence is insufficient to confirm it works for the specific conditions it has been studied for. See the graded list on this page, and talk to your pharmacist or doctor before relying on it for any condition.
Does Pau D'arco interact with prescription medications?
Yes. We list 122 medications with a known interaction with Pau D'arco. Use the checker above to see how Pau D'arco interacts with a specific drug.
How are Pau D'arco interactions rated?
Each interaction is graded major, moderate, or minor based on how clinically significant it is and the strength of the evidence behind it. Major interactions are the most serious and are best avoided, or used only under close professional supervision.
Is it safe to take Pau D'arco with my medications?
It depends on the specific medication. Some combinations are fine, while others call for monitoring, timing changes, or should be avoided. Check your exact drug above and confirm with your pharmacist or doctor before starting, stopping, or changing anything.
Where does this Pau D'arco interaction information come from?
Our interaction data is built on the Natural Medicines database — an evidence-graded reference for vitamins, herbs, and supplements — and is reviewed by licensed HelloPharmacist pharmacists, who may add clinical context.
What is Pau D'arco used for?
People traditionally use Pau D'arco for infections, inflammation, immune support, digestive issues, and skin problems, but strong human evidence supporting these uses is lacking.
Is Pau D'arco safe to take?
Small amounts taken briefly, such as the tea, are generally tolerated, but higher doses can be toxic and may increase bleeding risk, so it should be used cautiously and discussed with a healthcare provider.
Can I take Pau D'arco while pregnant or breastfeeding?
No. It should be avoided during pregnancy because of possible harm to the baby, and there isn't enough safety information to recommend it while breastfeeding.
Does Pau D'arco cure infections or cancer?
No. While certain compounds show activity in lab studies, Pau D'arco is not a proven treatment for any infection or cancer and should never replace medical care.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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Products that contain Pau D'arco

A rotating sample of real supplements in our database that list Pau D'arco — open any to see its full ingredients and every drug interaction we check.

See all 721 products with Pau D'arco →
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