What is Cannabis? Cannabis, also known as marijuana, is a plant first grown in Central Asia that is now grown in many parts of the world. The Cannabis plant makes a resin (thick substance) that contains compounds called cannabinoids. Some cannabinoids are psychoactive (affecting your mind or mood). In the United States, Cannabis is a controlled substance and has been classified as a Schedule I agent (a drug with a high potential for abuse and no accepted medical use). Hemp is a mixture of the Cannabis plant with very low levels of psychoactive compounds. Cannabidiol (CBD) oil is also made from hemp. Hemp is not a controlled substance, but CBD is. See the General Information section of the health professional version of the Cannabis and Cannabinoids summary for more information on medicinal Cannabis products. Clinical trials that study Cannabis for cancer treatment are limited. By federal law, possessing Cannabis (marijuana) is illegal in the United States unless it is used in approved research settings. However, a growing number of states, territories, and the District of Columbia have passed laws to legalize medical marijuana. (See Question 3).

What are cannabinoids? Cannabinoids, also known as phytocannabinoids, are chemicals in Cannabis that cause drug-like effects in the body, including the central nervous system and the immune system. The main psychoactive cannabinoid in Cannabis is delta-9-THC. Another active cannabinoid is cannabidiol (CBD), which may relieve pain and lower inflammation without causing the high of delta-9-THC. Cannabinoids may help treat the side effects of cancer and cancer treatment.

If Cannabis is illegal, how do some cancer patients in the United States use it? Although federal law prohibits the use of Cannabis, the map below shows the states and territories that have legalized Cannabis for medical purposes. Some other states have legalized only one ingredient in Cannabis, such as cannabidiol (CBD), and these states are not included in the map. Medical marijuana laws vary from state to state. Enlarge A map showing the U.S. states and territories that have approved the medical use of Cannabis.

How is Cannabis given or taken? Cannabis may be taken by mouth (in baked products or as an herbal tea) or may be inhaled. When taken by mouth, the main psychoactive ingredient in Cannabis (delta-9-THC) is processed by the liver and changed into a different psychoactive chemical (11-OH-THC). When Cannabis is smoked and inhaled, cannabinoids quickly enter the bloodstream. The psychoactive chemical (11-OH-THC) is made in smaller amounts than when taken by mouth. A growing number of clinical trials are studying a medicine made from an extract of Cannabis that contains specific amounts of cannabinoids. This medicine is sprayed under the tongue.

Have any laboratory or animal studies been done using Cannabis or cannabinoids? In laboratory studies, tumor cells are used to test a substance to find out if it is likely to have any anticancer effects. In animal studies, tests are done to see if a drug, procedure, or treatment is safe and effective in animals. Laboratory and animal studies are done before a substance is tested in people. Laboratory and animal studies have tested the effects of cannabinoids in laboratory experiments. See the Laboratory/Animal/Preclinical Studies section of the health professional version of Cannabis and Cannabinoids for information on laboratory and animal studies done using cannabinoids.