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Topics in Complementary and Alternative Therapies (PDQ®)

Health Professional Version

Botanicals/Herbal Products

Black Cohosh

Black cohosh is a substance obtained from the root of a perennial herb used in some cultures to treat a number of medical problems. Black cohosh has been studied for reducing hot flashes. Clinical trials of black cohosh that have been well designed with a randomized placebo-controlled arm have also found that black cohosh is no better than a placebo in reducing hot flashes. Refer to the Herbs/dietary supplements section in the PDQ summary on Hot Flashes and Night Sweats for more clinical trial information about black cohosh.

Cannabis and Cannabinoids

Cannabis, also known as marijuana, originated in Central Asia but is grown worldwide today. In the United States, it is a controlled substance and is classified as a Schedule I agent (a drug with increased potential for abuse and no known medical use). The Cannabis plant produces a resin containing psychoactive compounds called cannabinoids. The potential benefits of medicinal Cannabis for people living with cancer include antiemetic effects, appetite stimulation, pain relief, and improved sleep. Refer to the PDQ summary on Cannabis and Cannabinoids for more information.

Essiac/Flor Essence

Essiac and Flor Essence are herbal tea mixtures originally developed in Canada. They are marketed worldwide as dietary supplements. Proponents have claimed that Essiac and Flor Essence can help detoxify the body, strengthen the immune system, and fight cancer. No controlled data are available from human studies to suggest that Essiac or Flor Essence can be effective in the treatment of patients with cancer. Refer to the PDQ summary on Essiac/Flor Essence for more information.


Flaxseed comes from the seed of the flax plant and is a rich source of omega-3 fatty acid, fiber, and a compound called lignin. It is being studied in the prevention of several types of cancer. Flaxseed has also been studied for its effect on hot flashes. Refer to the Herbs/dietary supplements section in the PDQ summary on Hot Flashes and Night Sweats for information about clinical trials that have studied flaxseed.


Ginger is an herb with a root that has been used in cooking and by some cultures to treat nausea, vomiting, and certain other medical conditions. It has been studied for reducing nausea in cancer patients. Refer to the Ginger section in the PDQ summary on Nausea and Vomiting for information about randomized controlled trials of ginger in cancer patients.


Ginseng, another popular supplement used to treat fatigue, was studied in patients with cancer who were either undergoing anticancer treatment or had completed treatment. There was a significant and clinically meaningful difference favoring the ginseng group over the placebo group. Refer to the Intervention section in the PDQ summary on Fatigue for more information.


L-carnitine is a dietary supplement believed to be helpful for the treatment of cancer-related fatigue because of its role in cellular energy metabolism and its ability to decrease proinflammatory cytokines. Refer to the Intervention section in the PDQ summary on Fatigue for information about a phase III study that compared L-carnitine with placebo.

Milk Thistle

Milk thistle is a plant whose fruit and seeds have been used for more than 2,000 years as a treatment for liver and biliary disorders. The active substance in milk thistle is silymarin. Laboratory studies demonstrate that silymarin functions as an antioxidant, stabilizes cellular membranes, stimulates detoxification pathways, stimulates regeneration of liver tissue, inhibits the growth of certain cancer cell lines, exerts direct cytotoxic activity toward certain cancer cell lines, and may increase the efficacy of certain chemotherapy agents. Refer to the PDQ summary on Milk Thistle for more information.

Mistletoe Extracts

Mistletoe is a semiparasitic plant that has been used for centuries to treat numerous human ailments. It is used commonly in Europe, where a variety of different extracts are manufactured and marketed as injectable prescription drugs. These injectable drugs are not available commercially in the United States and are not approved as a treatment for people with cancer. Refer to the PDQ summary on Mistletoe Extracts for more information.


PC-SPES is a patented mixture of eight herbs. Each herb used in PC-SPES has been reported to have anti-inflammatory, antioxidant, or anticarcinogenic properties. PC-SPES was recalled and withdrawn from the market because certain batches were contaminated with Food and Drug Administration–controlled prescription drugs. The manufacturer is no longer in operation, and PC-SPES is no longer being made. Refer to the PDQ summary on PC-SPES for more information.

St. John’s wort

St. John’s wort is a plant with yellow flowers whose medicinal uses were first recorded in ancient Greece. The major active constituents in St. John's wort are hypothesized to be melatonin, hypericin, hyperforin, and adhyperforin, although hypericin may not reach sufficient concentrations in humans to have biologic activity. Refer to the St. John's wort section in the PDQ summary on Depression for more information about clinical trials that have studied St. John’s wort as a treatment for depression.

Selected Vegetables/Sun's Soup

“Selected Vegetables” and “Sun’s Soup” are names given to several different mixtures of vegetables and herbs that have been studied as treatments for cancer. These mixtures were developed by a single individual. Two formulations of Selected Vegetables/Sun’s Soup are marketed in the United States as dietary supplements. The vegetables and herbs in Selected Vegetables/Sun’s Soup are thought to have anticancer and/or immune-system–stimulating properties. Existing data supporting the effectiveness of Selected Vegetables/Sun’s Soup as a treatment for cancer are limited and weak. Refer to the PDQ summary on Selected Vegetables/Sun’s Soup for more information.

  • Updated: June 11, 2014