Other common name(s): lapachol, lapacho, lapacho morado, lapacho Colorado, ipe roxo, ipes, taheebo, tahuari, trumpet bush, trumpet tree
Scientific/medical name(s): Tabebuia impetiginosa, Tabebuia avellanedae, Tabebuia heptaphylla, Tabebuia ipé
Pau d’arco is a large tree that grows naturally in the rainforests of Central and South America. It may be cultivated in southern Florida. There are about 100 species of the tree, which produces large flowers and can grow to 150 feet tall and 6 feet in diameter. Tebebuia impetiginosa produces purple or pink flowers, while other varieties produce yellow or white flowers. The inner bark of the tree is used in herbal remedies.
Laboratory and animal studies suggest that lapachol and other compounds extracted from or made from pau d’arco may have some effects against certain illnesses. At this time, available evidence from well-designed, controlled studies does not support this substance as an effective treatment for cancer in humans. Pau d’arco also has potentially dangerous side effects.
The Tabebuia impetiginosa tree is now on the endangered species list. There is concern, and some evidence, that bark from other types of trees is sometimes sold as pau d’arco. Quality and composition of supplements varies widely.
How is it promoted for use?
Pau d’arco is promoted as a cure for dozens of illnesses and medical conditions, including arthritis, ulcers, diabetes, and cancer. Proponents also claim that, when taken internally, pau d’arco relieves infections, reduces inflammation, promotes digestion, strengthens the immune system, flushes toxins from the body, and protects against cardiovascular disease and high blood pressure. Proponents also use it to treat lupus, osteomyelitis, Parkinson’s disease, psoriasis, and to relieve pain. Some use the boiled bark externally as a poultice or use the strained liquid as a wash to treat skin inflammations, fungal infections, hemorrhoids, eczema, and wounds.
What does it involve?
Pau d’arco is available as a capsule, tablet, salve, liquid extract, powder, and tea from health food stores, many drugstores, and Internet sources. Recommended dosage varies by manufacturer. When making tea, practitioners say the bark must be boiled or simmered for at least 8-10 minutes to release the active ingredients, which do not dissolve easily in water.
What is the history behind it?
Tea made from pau d’arco is thought to have been used by the ancient Incas and natives of the South American rain forests, who took it to cure disease and as a tonic to strengthen the body and improve overall health. Caribbean folk healers reportedly use the leaf and the bark to treat backaches, toothaches, and sexually transmitted diseases. The native tribes of Brazil used the tree to make bows for hunting. When the Portuguese colonized Brazil, they named the tree pau d’arco, which means "bow stick." The herb remains a popular Brazilian folk remedy.
New interest in pau d’arco arose in the mid-1960s, when a Brazilian physician claimed that the substance could relieve pain, increase the number of red blood cells, and cure numerous illnesses, including cancer. The NCI sponsored a study of lapachol (an extract of pau d’arco) in humans, but studies stopped when it was understood that the amount required to affect tumors also interfered with blood clotting. The new drug application for lapachol was closed out in 1970. It was no longer pursued as a cancer treatment agent, although a few studies have been done since. Canada banned the substance in 1985.
Since the early 1980s, health food stores in the United States have sold pau d’arco, which is promoted as a treatment for many kinds of medical complaints. As of 2012, Brazil has listed the pau d’arco tree as endangered; which might limit availability of the tree bark.
What is the evidence?
One of the active ingredients in pau d’arco that has been studied is called lapachol. In laboratory animals, lapachol was found to act against malaria and certain kinds of animal tumor cells, such as sarcoma, but it did not have an effect against other kinds of cancer, including leukemia and adenocarcinoma. Some studies in rodents have also shown that higher doses of lapachol can promote cancer metastasis (spread), as well as cause changes in DNA that might promote cancer. Further studies would be required to determine whether these results apply to humans.
There have only been a few studies on lapachol in humans. An uncontrolled study sponsored by the National Cancer Institute in the early 1970s found no toxic effects on liver or kidney tissue. However, lapachol did prevent blood from clotting, and doses thought to be high enough to affect tumors posed a serious risk of bleeding. Clotting function returned to normal after the drug was stopped.
Beta-lapachone is another compound from pau d’arco that is being studied at as a possible cancer treatment. These studies have been done in the lab, rather than in humans, but so far they show some effect on cancer cells growing in a dish. Studies in humans will be needed to find out if beta-lapachone can actually slow cancer growth.
Unconfirmed tests showed that the tree bark stimulated immune system cells called macrophages into action. The substance also killed lung cancer cells and liver cancer cells grown in test tubes and reduced the rate of lung cancer spread in mice after surgery to remove the cancerous tumor. The bark extract also may kill bacteria or fungi.
Pau d’arco contains at least 20 active compounds, such as naphthaquinones (of which lapachol is one), anthroquinones, quercetin, and other flavonoids with effects that are not fully known. In a 2004 study, 2 compounds made from naphthaquinones showed promise in animal studies for malaria treatment. It is important to note, however, that studies of purified extracted compounds would not be expected to yield the same results as studies of the raw bark, which contains a number of compounds in varying amounts.
Are there any possible problems or complications?
Pau d’arco has some potentially serious side effects. Some of the chemicals in pau d’arco, such as hydroquinone, are known to be toxic. High doses taken internally may cause liver and kidney damage. In animal studies, birth defects and deaths occurred among rats whose mothers were given lapachol during pregnancy. Pau d’arco should be avoided, especially by women who are pregnant or breastfeeding.
Even fairly low doses of pau d’arco can cause dizziness, nausea, vomiting, and diarrhea and can interfere with blood clotting. The resulting bleeding can cause anemia. In addition, pau d’arco, when taken by mouth, can interact with aspirin and blood-thinning drugs, further increasing the risk of bleeding. It may also increase the risk of bleeding in people with hemophilia or other clotting disorders. It caused some DNA mutations in rodents; and caused lighter-weight seminal vesicles (semen producing glands) in adult male rats, but it is not clear if it would have the same effects in humans.
The bark of the tree can sensitize skin and has caused asthma in work settings where people are exposed to the wood dust. Allergic reactions are possible.
Twelve commercial pau d’arco products that were tested in Canada showed that only one contained lapachol, which normally makes up about 7 percent of pau d’arco, suggesting the products likely contained other substances. Concerns persist that unrelated types of wood bark with similar colors are being substituted and sold as pau d’arco. It is very difficult to be sure what types of trees are included, since there are other trees from South America that look like pau d’arco but are not chemically similar.
The potential interactions between pau d'arco and other drugs and herbs should be considered. Some of these combinations may be dangerous. Always tell your doctor and pharmacist about any herbs you are taking.
Relying on this type of treatment alone and avoiding or delaying conventional medical care for cancer may have serious health consequences.
To learn more
More information from your American Cancer Society
The following information on complementary and alternative therapies may also be helpful to you. These materials may be found on our Web site (www.cancer.org) or ordered from our toll-free number (1-800-227-2345).
The ACS Operational Statement on Complementary and Alternative Methods of Cancer Management
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Note: This information may not cover all possible claims, uses, actions, precautions, side effects or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for consultation with your doctor, who is familiar with your medical situation.
Last Revised: 01/16/2013