Pau d'arco (Tabebuia avellanedae) is native to South America, where it has been used to treat a wide range of conditions. They include pain, arthritis, inflammation of the prostate gland (prostatitis), fever, dysentery, boils and ulcers, and various cancers.

Scientists have identified two active chemicals in pau d'arco called naphthoquinones: lapachol and beta-lapachone. In lab tests, these chemicals kill some bacteria, fungi, viruses, and parasites. They also have anti-inflammatory properties. But no one knows whether they will have the same effects when taken by humans, and usually the dose that's needed would have severe, toxic side effects.

Pau d'arco is sometimes used for the following conditions, although there is no evidence it works:

• Candidiasis (a vaginal or oral yeast infection)
• Herpes simplex virus
• Influenza
• Parasitic diseases, such as schistosomiasis
• Bacterial infections, such as brucellosis

Test tube and animal studies have looked at whether pau d'arco has any effect on cancer. These tests have shown mixed results. Even in studies where pau d'arco does reduce the number of cancer cells, the amounts used would be toxic to humans.

The same is true of some of the doses that might be needed to kill bacteria or viruses. If you decide to take pau d'arco, do so only under your doctor's supervision.

The pau d'arco tree is an evergreen tree that grows in the warm parts of Central and South America. It is a broad-leaf evergreen that grows to a height of 125 feet and has pink to violet-colored flowers. Its extremely hard wood makes it resistant to disease and decay. The inner bark of the tree is used medicinally. In recent years there has been an increasing demand for pau d'arco, causing the trees to be endangered.

Most of the chemical research on pau d'arco has been done on the wood and not the inner bark. Pau d'arco contains chemical compounds called naphthoquinones, specifically lapachol and beta-lapachone. They seem to have antifungal, antiviral, and antibacterial properties. They also contain significant amounts of the antioxidant quercetin.

Pau d'arco is sold as tablets, dried bark tea, and tincture (which contains alcohol). The chemicals that give pau d'arco its medicinal effects don't dissolve well in water, so a tea is not recommended.

Most pau d'arco products are not standardized, so it is hard to determine whether or not they contain a safe amount of these active substances. It is important to carefully read the label to make sure that the product actually contains Tabebuia avellanedae as an ingredient.

Pediatric

Do NOT give pau d'arco should to infants or children.

Adult

It is important to discuss the dose with your doctor, since large amounts of pau d'arco can be toxic. The risk of side effects seems to be greater when the dose of lapachol is more than 1.5 g per day. However, it can be hard to determine how much lapachol the powdered bark contains.

• Capsules: 300 - 500 mg three times per day
• Tincture (1:5): 0.5 - 1 mL (about 1/8 - 1/4 tsp.) two or three times per day

The use of herbs is a time-honored approach to strengthening the body and treating disease. Herbs, however, can trigger side effects and can interact with other herbs, supplements, or medications. For these reasons, herbs should be taken with care, under the supervision of a health care practitioner.

Talk to your doctor to determine the proper dose of pau d'arco, because too much can be dangerous.

At recommended doses, side effects are uncommon but may include anemia, nausea, diarrhea, and dizziness.

High doses can cause uncontrolled bleeding and vomiting.

Pregnant and nursing women should not take pau d'arco.

Antiplatelet and anticoagulant drugs (blood-thinners) -- Pau d'arco may affect the blood's ability to clot, and could interfere with any blood-thinning drugs you are taking, including:

• Warfarin (Coumadin)
• Clopidogrel (Plavix)
• Aspirin

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