What Is Marijuana?

Marijuana or Cannabis sativa is an herb. It grows in many places around the world. It is also called hemp, reefer, or cannabis. It has had many uses in different cultures. These include reducing pain and increasing appetite. Marijuana contains chemicals called cannabinoids. The best known is tetrahydrocannabinol or THC. The marijuana "high" is mainly due to THC.

Marijuana was used medically in the U.S. until the late 1930s. Then there were claims of "reefer madness." Supposedly, marijuana caused crime, violence, insanity, and death. In 1970, U.S. drug law classified marijuana as having a high potential for abuse and no medical use.

Marijuana was later found to have other health benefits. It can lower pressure within the eye. This helps treat glaucoma, an eye disease which can cause blindness. Marijuana also reduces nausea and vomiting in patients taking chemotherapy treatment for cancer. It reduces muscle spasms in people with nerve problems like multiple sclerosis and can help treat some types of pain. These uses led to the development of the drug dronabinol (Marinol), a synthetic version of THC.

NOTE: Federal and state laws generally forbid the sale or possession of marijuana. Twenty states and the District of Columbia have passed "medical marijuana" laws that permit limited use for health reasons. In 2009, the US government announced that federal agents will not arrest medical marijuana patients or providers who comply with state law. More information on state medical marijuana laws is available at www.mpp.org/.

Why Do People With HIV Use Marijuana?

People with HIV use marijuana to stimulate appetite and to reduce nausea. Many people with HIV have low appetite. This can be due to fatigue or drug side effects. Low appetite can lead to AIDS wasting (see Fact Sheet 519). Marijuana stimulates the appetite, preventing these problems.

Some people with HIV get nauseated when they take antiretroviral medications (ARVs). This can make it difficult to take all scheduled doses. Marijuana can help control the nausea.

It may also relieve the pain of peripheral neuropathy (see Fact Sheet 555). A recent study confirmed it is useful for that purpose.

How Is Marijuana Used?

Normally, dried marijuana leaves and flowers are smoked or baked into food. Health care providers can legally prescribe Marinol. Some people get the same effects from Marinol as from smoked marijuana. Others prefer to smoke marijuana. They can use just the amount they need without bad effects from higher doses.

What Are the Side Effects?

Smoking marijuana can cause some of the same health problems as smoking tobacco, including bronchitis. However, it has not been clearly linked to lung cancer.

Smoked or eaten marijuana can disrupt balance, physical coordination and visual perception. This can make it dangerous to drive a car or operate machinery. Some people feel stoned (very disoriented or dizzy) when using marijuana. This effect can be stronger when marijuana is eaten than when it is smoked.

Some users develop a tolerance to marijuana. This means they need higher and higher doses to get the same effect. Users can also become dependent on marijuana. They may have mild withdrawal symptoms when they stop using it.

How Does It Interact With Other Therapies?

There are no known interactions between marijuana and medications or other herbs. However, very few interactions between herbs and medications have been studied. Tell your health care provider if you are using any herbs or supplements.

A research study found that smoking marijuana does not increase HIV viral load or reduce CD4 cell counts.

How Do We Know It Works?

Many scientific studies document marijuana's ability to reduce nausea, increase appetite, and decrease pressure in the eye.

The Bottom Line

Marijuana is an herb that is smoked or baked into food. It has been used for health purposes for thousands of years. It was legal in the United States until the 1930s. It stimulates the appetite, reduces nausea and some types of pain, and reduces pressure inside the eye.

U.S. drug policy made marijuana illegal in 1970. However, health care providers can prescribe Marinol. It is a synthetic version of THC, an active substance in marijuana. Not everyone gets the same results from Marinol as from marijuana.

Some people with AIDS use marijuana to stimulate their appetites or to avoid nausea when taking their ARVs. A few states have passed medical marijuana laws that permit limited use for health purposes.

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