What Is Pau D’arco Used for and Are There Side Effects?

Pau d'arco is the name for a group of trees and a supplement made from the inner bark. Pau d'arco is used for pain, fever, boils, and other conditions and possible side effects include nausea, dizziness, diarrhea, and discolored urine.

Pau d’arco is the name for a group of trees and a supplement made from the inner bark. The tree bark — and products made from it — have been used in traditional medicine for hundreds of years. But — so far — human studies haven’t proven a single one of these effects. Too much of this supplement can cause dangerous side effects. 

Read on to learn the uses, side effects, and who can take pau d’arco.

Pau d’arco refers to a group of related trees primarily in the Tabebuia genus, including the four different species below: 

• Tabebuia avellanedae 
• Tabebuia heptaphylla
• Tabebuia heptaphylla
• Handroanthus impetiginosus

Pau d’arco is the common name to describe these trees and their products. They also go by different names in their countries of origin, including: 

• Lapacho
• Taheebo
• Ipe-roxo
• Trumpet bush 

These trees are native to South America. Tabebuia trees are evergreens with broad leaves. They grow to an average of 125 feet tall and produce clusters of pink and violet flowers. The trees are well known for having sturdy hardwood interiors that are exceptionally resistant to disease and decay. 

Traditionally, the inner bark of the tree, harvested for medicinal purposes, is made into brewed tea by many South American cultures. In Brazil, for example, people still use pau d’arco the same way their ancestors did hundreds of years ago. It supposedly helps with a wide range of health problems. 

Today you can acquire pau d’arco in many forms other than tea, including the following: 

• Pill or tablet
• Powder
• Alcohol-based tincture

The bark was harvested sustainably for generations. Unfortunately, the current demand for pau d’arco supplements has led to the widespread destruction of the trees, making them now endangered. 

People who practice traditional medicine recommend using pau d’arco to help treat and manage a wide range of health problems. Modern pau d’arco supplements also tend to include a variety of health claims on their labels — some derived from these traditional uses.

The problem is that modern science hasn’t verified any of these claims. At present, no evidence taking pau d’arco will lead to any definitive health benefits.  

Traditional and claimed uses for pau d’arco include treating: 

• Pain
• Fever
• Boils
• Ulcers
• Colds and the flu
• Bladder infections
• Diabetes
• Arthritis
• Prostatitis — inflammation of the prostate gland
• Certain cancers

So far, very few studies have looked into the effects of pau d’arco supplements on the human body. But chemical analysis has found two molecules that could affect human health. These chemicals are called naphthoquinones, specifically lapachol and beta-lapachone. 

These chemicals have shown biological effects in both test tube and animal-based experiments. These properties include: 

• Anti-inflammatory
• Antibacterial
• Antifungal
• Anticancer 

But — so far — none of these properties are linked to significant results in humans. One of the few human studies done to date did not find any changes in people with leukemia when they took lapachol. Another human study found that pau d’arco may help prevent certain oral complications in people undergoing radiotherapy for throat cancer. But the results were limited. 

Clinical trials are investigating the use of pau d’arco supplements for conditions like certain menstrual disorders. New data is available consistently. Talk to your doctor to find the most up-to-date information on the proven uses of pau d’arco supplements. 

The chemicals in pau d’arco can cause side effects — even when taking the recommended amount. These side effects include: 

• Nausea
• Diarrhea
• Dizziness
• Discolored urine

High doses can cause more significant problems, including uncontrollable bleeding and vomiting. You should seek immediate medical attention if you develop either of these problems while taking pau d’arco. 

Researchers have seen additional side effects in animal studies that could also be relevant to human models. These include: 

• Anemia
• Reproductive abnormalities
• Chromosomal abnormalities — changes to the structures that store your genetic information

It can be challenging to determine the correct dose with pau d’arco supplements. The U.S. Food and Drug Administration (FDA) doesn’t monitor or regulate supplements the same way that they do prescription medications. This lack of monitoring means there can be a lot of variation between brands and from one batch to another. 

When picking out a pau d’arco product, ensure you check the active ingredients for the presence of pau d’arco or Tabebuia. Also, make sure that the amount isn’t too high. Your risk of side effects increases if you take more than one and a half milligrams of lapachol a day. It’s difficult to determine how much of each ingredient is present per sample. 

The amount of lapachol and beta-lapachone in each sample depends on a large number of factors, including: 

• The exact species and part of the plant used for extraction
• The extraction methods
• The product’s final form — for example, neither chemical dissolves well in water, so it is not easy to extract them when you use bark to make tea

With these variables, your best bet is to ask your doctor for the safest brand recommendations. 

Don’t give pau d’arco to infants and children. It also shouldn’t be taken by people who are pregnant or breastfeeding. There isn’t enough available data to determine whether or not pau d’arco is safe for these groups of people. 

Pau d’arco can also create complications if taken with certain prescriptions, over-the-counter medications, and other supplements. Don’t use pau d’arco if you also take: 

• Prescription blood thinners — like warfarin and clopidogrel 
• Non-steroidal anti-inflammatory medications (NSAIDs) — like ibuprofen and naproxen
• Certain natural remedies — including celery, chamomile, garlic, ginger, clove, and turmeric 

This list isn’t comprehensive. Get permission from your doctor before taking any form of pau d’arco.

Always talk to your doctor before taking pau d’arco in any form. If they’ve already approved your use of pau d’arco, you should consult them before starting other new supplements so they can double-check for problematic interactions. They can also monitor your health for any signs of complications. 

Get immediate medical attention if you experience severe symptoms after starting pau d’arco supplements. Even if you’ve been taking pau d’arco for a while, there could be problems specific to your current batch of supplements. 

In the case of an emergency surgery or another medical emergency, you need to tell your care team that you take pau d’arco. This information will be important when deciding the best way to treat you. 

Make sure to talk to your doctor if you have any questions or concerns about pau d’arco or the effectiveness of dietary supplements.