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Other common name(s): pencil cactus, pencil tree, milkbush, petroleum plant

Scientific/medical name(s): Euphorbia tirucalli, Euphorbia viminalis, Euphorbia insulana


Aveloz is the Spanish name for a succulent shrub that grows in the tropical areas of Africa, Brazil, and Madagascar. This relative of the poinsettia is sometimes grown as a houseplant. The sap, leaves, and root of various species of the shrub have been used in folk medicine for centuries.


Aveloz sap is promoted for use as an anticancer agent. However, laboratory and animal studies do not support this claim. In fact, they suggest that aveloz sap may actually suppress the immune system, promote tumor growth, and lead to the development of certain types of cancer.

The sap can burn the skin, damage the eyes, and even cause blindness. If taken internally, it can cause burning of the mouth and throat, vomiting, diarrhea, and other serious problems.

How is it promoted for use?

The sap of the aveloz shrub has been promoted as a tumor-killing agent for people with cancer. It is promoted for use on the skin or to be taken by mouth. It is said to burn off warts, cysts, and skin cancers, especially on the face. In various parts of the world, the plant is also used to treat leprosy, earache, abscesses, toothaches, asthma, colic, cough, rheumatism, and fractures.

What does it involve?

In the United States, aveloz is sold in liquid form by some health food stores and herbal practitioners. To treat cancer, benign tumors, warts, and cysts, practitioners recommend drinking five drops of the liquid dissolved in half a glass of water or tea. Aveloz is also sold as an ointment to be applied directly to warts, skin growths, and tumors.

What is the history behind it?

In some tropical areas of Africa, Euphorbia tirucalli has long been recognized as a fish poison. The plants are crushed and placed into rivers so that fish can be easily caught when they float to the surface.

Thousands of years ago, Amazon Indians in Brazil began applying the sap of the aveloz plant to warts and tumors on the skin. By the 1770s, it was used against cancerous tumors in African folk medicine. In the 1880s, a Brazilian physician introduced the plant to conventional medicine.

In the 1970s, some U.S. tabloids began proclaiming aveloz as a cure for cancer when taken internally, saying, "One drop of sap, diluted in a glass of distilled water and taken by the tablespoon every hour, eliminates cancerous growths in one week." The craze over aveloz as a cure for cancer peaked in the 1980s, but it is still sold at some Internet sites as an alternative treatment for cancer.

What is the evidence?

The effects of aveloz have only been studied in the laboratory and in animals, but the results suggest that aveloz may actually promote tumor growth. These early studies suggested that the sap and the plant itself may suppress the body's immune system, making it less resistant to infections and some types of cancer. This may lead to an activation of the Epstein-Barr virus (the same virus that causes mononucleosis) and the development of a type of cancer known as Burkitt lymphoma. In light of this information, no recent cancer studies in humans have been completed on this plant.

One study suggests that chemicals from Euphorbia tirucalli may enhance the immune system of mice with cancer. However, no human studies have been published. Some studies in the lab are still going on to find out how these chemicals affect human cells. Extensive testing will be necessary to determine whether any of these extracts might be suitable for human use. At present, research seems more focused on the use of the sap to kill mosquitoes in the larval stage.

There are many kinds of plants in the Euphorbia genus, some of which are being tested for use against leukemia. Certain extracts look promising in laboratory experiments.

Are there any possible problems or complications?

This product is sold as a dietary supplement. Unlike companies that produce drugs (which must be tested before being sold), the companies that make supplements are not required to prove to the US Food and Drug Administration that their supplements are safe or effective, as long as they don't claim the supplements can prevent, treat, or cure any specific disease.
Some such products may not contain the amount of the herb or substance that is on the label, and some may include other substances (contaminants). Actual amounts per dose may vary between brands or even between different batches of the same brand. In 2007, the FDA wrote new rules to improve the quality of manufacturing for dietary supplements and the proper listing of supplement ingredients. But these rules do not address the safety of the ingredients or their effects on health.
Most such supplements have not been tested to find out if they interact with medicines, foods, or other herbs and supplements. Even though some reports of interactions and harmful effects may be published, full studies of interactions and effects are not often available. Because of these limitations, any information on ill effects and interactions below should be considered incomplete.

Aveloz sap can cause chemical burns, making blisters or ulcers on skin and mucous membranes (the moist pink layer of cells that lines the eyes, nose, mouth, and other openings of the body). Sap from the plant can irritate skin and damage the eyes. Blindness has even been reported after untreated eye exposure.

If taken internally, the plant or its sap can cause burning of the mouth and throat, nausea, vomiting, diarrhea, and stomach cramps. It has been reported to have caused some deaths in eastern Africa. Children and pets may be harmed if they eat the plants or sap.

Relying on this type of treatment alone and avoiding or delaying conventional medical care for cancer may have serious health consequences.

Additional resources

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-ACS-2345).

Dietary Supplements: What Is Safe?

The ACS Operational Statement on Complementary and Alternative Methods of Cancer Management

Complementary and Alternative Methods and Cancer

Placebo Effect

Learning About New Ways to Treat Cancer

Learning About New Ways to Prevent Cancer


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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 Medical Review: 04/01/2011
Last Revised: 04/01/2011