Herb & supplement monograph

Pao Pereira Drug Interactions, Uses, Effectiveness, Safety & More

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

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

But these pages have grown well beyond that into a full monograph — what Pao Pereira 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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Interaction report

Drugs that interact with Pao Pereira

0 medications have a known interaction with Pao Pereira, graded by severity. Select any drug for the full evidence-based detail.

We don’t currently list any known drug interactions for Pao Pereira. This doesn’t guarantee none exist — always confirm with your pharmacist before combining supplements with your medications.

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 Pao Pereira combination — clinical detail, likelihood, evidence level, and citations.
  • Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.
Monograph

Pao Pereira: Uses, Safety & Side Effects

Medically reviewed by · Reviewed June 2026 ·
The bottom line

Pao Pereira is a bark extract from a South American tree that is marketed mainly as a complementary cancer and immune-support supplement. Human evidence is very limited, and most research comes from laboratory and animal studies, so it should not be used in place of proven medical care. Talk with your pharmacist or doctor before trying it, especially if you have a serious health condition.

Scientific name
Geissospermum laeve
Family
Apocynaceae
Part used
Bark (and bark extract)
Common forms
Capsules, tinctures, liquid extracts, powdered bark
People commonly use it for
  • Immune support
  • Cancer support (complementary use)
  • Antimalarial/fever (traditional)
  • Digestive complaints (traditional)
  • General tonic

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

Safety at a glance
OverallUse caution

Human safety data are limited, so use with care and professional guidance.

PregnancyInsufficient reliable information

Insufficient reliable information available; avoid using.

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

Pao Pereira is a supplement made from the bark of a tree (Geissospermum laeve) that grows in the rainforests of South America, especially in the Amazon region of Brazil. It belongs to the same plant family as many other plants known for their potent natural compounds.

In traditional Amazonian medicine, the bark has been used for fevers, malaria, digestive problems, and as a general tonic. Today, it is most often sold as a capsule, tincture, or liquid extract and marketed as a supplement for immune support and as a complementary product for people with cancer.

How it works

Pao Pereira bark contains a group of natural compounds called indole alkaloids (such as flavopereirine). In laboratory studies, these compounds appear to slow the growth of certain cancer cells and may interfere with how cancer cells divide.

Researchers have also looked at possible antioxidant and immune-related effects. However, most of these findings come from cells grown in a dish or from animal studies. It is not clear whether the same effects happen in the human body or at the doses found in supplements.

Effectiveness

Does Pao Pereira work?

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

Evidence overview · 3 uses evaluated
3 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 Pao Pereira, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.

Also studied for 3 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 pao pereira for cancer, there is insufficient reliable information about the clinical effects of pao pereira for this purpose.

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

Although there has been interest in using oral pao pereira for constipation, there is insufficient reliable information about the clinical effects of pao pereira for this purpose.

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

Although there has been interest in using oral pao pereira for sexual arousal, there is insufficient reliable information about the clinical effects of pao pereira 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

Because there is little formal safety research, the full risks of Pao Pereira in humans are not well understood. Supplements are not tested or approved by the FDA the way medicines are, so product quality and strength can vary widely between brands.

People with serious health conditions, especially those being treated for cancer, should talk with their oncologist and pharmacist first, since herbal products can affect how the body handles treatment. People with liver or kidney problems should also be cautious.

During pregnancy and breastfeeding, avoid Pao Pereira because there is not enough safety information. It is also best to avoid giving it to children.

Side effects

Reported side effects are not well documented because of the lack of human studies. As with many herbal extracts, possible effects include stomach upset, nausea, or digestive discomfort.

Allergic reactions are always possible with plant products. Stop using it and seek medical care if you notice rash, swelling, trouble breathing, or other signs of a serious reaction. Because long-term safety is unknown, watch for any new or unusual symptoms and report them to your healthcare provider.

Dosing

There is no established or standardized dose for Pao Pereira. Different products contain different amounts and strengths of bark extract.

If you choose to use it, follow the directions on the product label and do not exceed the recommended amount. It is best to check with your pharmacist or doctor before starting, and to choose products from reputable companies that test for quality.

Pregnancy & Breastfeeding

Pao Pereira & Pregnancy

Insufficient reliable information

Insufficient reliable information available; avoid using.

Pao Pereira & 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 4 sources that drive our Pao Pereira monograph — publicly available pages from reputable medical and government organizations. Every link was verified to work before publishing.

  1. About Herbs, Botanicals & Other Products — Memorial Sloan Kettering Cancer Center Source
  2. Using Dietary Supplements Wisely — NIH NCCIH Source
  3. Dietary Supplements: What You Need to Know — NIH Office of Dietary Supplements Source
  4. Herbs at a Glance — NIH NCCIH Source
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.

Brand directory

Brands that make products with Pao Pereira

1 brand in our database make a supplement containing Pao Pereira.

Product directory

Supplement products with Pao Pereira

1 product in our database contain Pao Pereira. Open any to see its full ingredient list and every drug interaction we check.

Pharmacist Counseling Corner

Pao Pereira: Common Questions

What is Pao Pereira used for, and does it work?
People use Pao Pereira 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 Pao Pereira interact with prescription medications?
We do not currently list any known drug interactions for Pao Pereira. This does not guarantee that none exist, so always confirm with your pharmacist before combining it with your medications.
How are Pao Pereira 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 Pao Pereira 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 Pao Pereira 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 Pao Pereira used for?
It is most often used as a complementary supplement for immune support and by some people with cancer, and traditionally for fevers and digestive issues. None of these uses are proven by strong human studies.
Does Pao Pereira cure cancer?
No. Some laboratory and animal studies suggest its compounds may affect cancer cells, but there is no reliable human evidence that it treats or cures cancer. It should never replace proven medical treatment.
Is Pao Pereira safe to take?
Human safety information is limited, so it should be used with caution and ideally under the guidance of a pharmacist or doctor, especially if you have a health condition.
Can I take Pao Pereira during pregnancy or breastfeeding?
No. There is not enough safety data, so it is best to avoid it while pregnant or breastfeeding.

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

Keep exploring

Products that contain Pao Pereira

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

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