Pau d’arco is a dietary supplement made from the inner bark of several species of Tabebuia trees that grow in Central and South America.

Its name refers to both the supplement and the trees from which it’s derived.

Also known as taheebo or lapacho, pau d’arco has long been used to treat a range of ailments. As a supplement, it’s marketed to reduce inflammation and promote weight loss.

This article explains pau d’arco’s uses, benefits, side effects, and dosage information.

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Pau d’arco is the common name for several species of trees native to South and Central America’s tropical rainforests.

It can grow up to 125 feet tall and has pink-to-purple flowers, which bloom before new leaves appear.

Its incredibly dense and rot-resistant wood is used by native peoples to make hunting bows. What’s more, tribes have long used its inner bark as a treatment for stomach, skin, and inflammatory conditions ().

Several compounds called naphthoquinones — mainly lapachol and beta-lapachone — have been isolated from this inner bark and are thought responsible for its purported benefits (, ).

That said, much of the research surrounding pau d’arco is limited to animal and test-tube studies — and therefore cannot be applied to humans.

Summary Pau d’arco is a supplement derived from the inner bark of a tropical tree that has been utilized in traditional medicine in Central and South America.

Research suggests that pau d’arco extract has antibacterial and antifungal properties.

While the exact mechanism remains unknown, pau d’arco is thought to inhibit the processes bacteria and fungi need to produce oxygen and energy (, ).

Several test-tube studies show that the bark extract provides protection against a number of disease-causing organisms and may also inhibit the growth of infectious bacteria in your digestive system.

For example, beta-lapachone has been found to inhibit and treat methicillin-resistant Staphylococcus aureus (MRSA), an infection which is notoriously difficult to control (, ).

In another study, pau d’arco extract inhibited the growth of Helicobacter (H.) pylori, a bacteria that grows in your digestive tract and has a tendency to attack your stomach lining, causing ulcers. That said, it was less effective than other common antibiotics ().

Since no human studies are available, the effectiveness or safety of pau d’arco extract for MRSA, H. pylori, and other infections remains unclear.

Summary Laboratory experiments suggest that pau d’arco extract may protect against a number of disease-causing organisms. These findings need to be replicated in humans before any recommendations can be made.

Pau d’arco extract is believed to inhibit inflammation — your body’s natural response to injury.

While low levels of inflammation are beneficial, chronic inflammation is thought to lead to diseases, such as cancer, obesity, and heart disease ().

Several animal and test-tube studies demonstrate that pau d’arco extract inhibits the release of specific chemicals that trigger an inflammatory response in your body.

For example, in one study, pau d’arco extract blocked inflammation in mice by 30–50%, compared to a placebo ().

As such, this supplement may help treat inflammatory conditions like osteoarthritis, which causes swelling, pain, and stiffness in your joints.

Similarly, another study in mice found that the bark extract blocked the production of compounds prevalent in many chronic inflammatory diseases ().

Taken together, these results suggest that pau d’arco may help relieve a variety of inflammatory conditions. However, studies in humans are needed before it can be recommended (, , ).

Summary Animal and test-tube studies note that pau d’arco extract can inhibit inflammation — though human research is needed.

Pau d’arco may aid weight loss.

Studies in mice demonstrate that pau d’arco extract inhibits pancreatic lipase, an enzyme that helps your body digest and absorb dietary fat. Blocking it reduces fat digestion — resulting in fewer absorbable calories (, ).

In one 16-week study, mice fed pau d’arco extract lost significantly more weight than those on a placebo — despite no changes in food intake ().

Similarly, in a trial in mice fed a high-fat diet, the extract protected against increases in body weight ().

However, it’s unclear whether pau d’arco extract would be effective for inhibiting dietary fat absorption in humans.

Even then, blocking dietary fat absorption can cause a number of side effects, including oily spotting on underwear, urgent bowel movements, inability to control bowel movements, loose stools, and fatty or oily stools ().

While untested, pau d’arco extract would likely cause these side effects if it inhibits fat absorption in humans.

Summary Pau d’arco extract may promote weight loss by inhibiting dietary fat absorption. However, this may come with a number of side effects — and human research is needed.

Pau d’arco extract is available in capsule, liquid, and powder form.

Traditionally, 2–3 teaspoons (10–15 grams) of the bark is simmered in water for 15 minutes and consumed as a tea 3 times per day.

But the beneficial compounds believed to give pau d’arco its effects are poorly extracted in water.

Liquid extracts of pau d’arco are a better choice because they’re made by dissolving the bark in alcohol, which draws out more of its potent compounds.

In fact, in a test-tube study examining various forms of pau d’arco, the liquid extract was the only form shown to inhibit tumor growth ().

Manufacturers typically recommend taking 1–2 ml of the liquid extract 3 times daily.

You can also buy pau d’arco in capsule form. Its suggested dose is 2–4 capsules of 500 mg taken 1–2 times per day.

While dosage information remains limited, appropriate dosage may vary depending on factors like age and weight.

Summary Pau d’arco is available as a pill, liquid, or powder. The liquid form likely contains more of the active compounds compared to the pill or powder.

Despite claims that pau d'arco may help treat cancer, no good evidence exists.

Although some of the compounds in pau d'arco show promise when applied to isolated cancer cells, the amount of extract needed to exhibit anticancer effects in the human body would be toxic (, ).

Research on the long-term safety of pau d’arco is lacking and largely unknown, as studies on its side effects are mostly limited to animals.

These side effects include (, , , ):

  • nausea
  • vomiting
  • blood thinning
  • urine discoloration
  • anemia
  • reproductive damage

Because pau d’arco extract may thin your blood, it should be avoided if you’re taking blood thinners or are scheduled to undergo surgery (, ).

It’s also not recommended to take pau d’arco if you’re pregnant or breastfeeding.

In addition, it’s important to ensure that your product comes from a reputable manufacturer.

Many pau d’arco supplements are purportedly made from sawdust from Brazilian lumber mills that use completely different species of trees — with none of pau d’arco’s beneficial compounds (, 29).

If you’re considering trying pau d’arco, first consult with your doctor.

Summary Due to a lack of human studies, the overall safety of pau d’arco is largely unknown. If you’re interested in trying it, make sure to talk to your doctor beforehand and purchase your supplement from a reliable manufacturer.

Pau d’arco is a supplement made from the inner bark of a tropical tree.

While test-tube and animal studies suggest that this bark helps treat certain infections and reduces inflammation, studies in humans are lacking.

Therefore, the effectiveness and safety of pau d’arco extract remain largely unknown.

Take caution if you’re interested in trying this supplement.