Medically reviewed on October 24, 2017
Marijuana is made from the dried leaves and buds of the Cannabis sativa plant. While the Food and Drug Administration (FDA) hasn't recognized or approved the use of marijuana as medicine, many states have legalized marijuana for medical use.
The FDA has approved two drugs, dronabinol (Marinol, Syndros) and nabilone (Cesamet), made from synthetic forms of ingredients found in marijuana. They can be legally prescribed for the treatment of nausea and vomiting caused by chemotherapy when other treatments have failed. Dronabinol might also be used for the treatment of anorexia associated with weight loss in people with AIDS.
Medical marijuana is available as an oil, pill, vaporized liquid and nasal spray, as dried leaves and buds, and as the plant itself. The herb is typically used to treat chronic pain, nausea and vomiting associated with cancer treatment and muscle spasms.
Research on the use of marijuana for specific conditions shows:
- Glaucoma. Marijuana might reduce the pressure in the eye caused by this eye condition. However, the effect appears to last only a few hours.
- Nausea and vomiting associated with cancer treatment. Research has shown that an active ingredient in marijuana, tetrahydrocannabinol (THC), effectively reduces nausea and vomiting in people undergoing chemotherapy.
- Pain. Marijuana use might reduce the intensity of shooting or burning pain often due to nerve damage (neuropathic pain) caused by HIV and other conditions.
- Seizures. It's not clear if marijuana effectively treats seizures.
- Spasticity. Marijuana use might reduce muscle stiffness or spasms caused by multiple sclerosis.
Evidence has shown that marijuana can effectively treat chemotherapy-induced nausea. It might also reduce spasticity related to multiple sclerosis and reduce the intensity of neuropathic pain.
However, marijuana use can cause cognitive impairment and should be used with caution if you have a mental health condition. In many places marijuana use is considered illegal for any purpose.
Safety and side effects
Medical marijuana use is generally considered safe. But different strains of marijuana have different amounts of THC. This can make dosing marijuana difficult.
Marijuana can cause:
- Dry mouth
- Dry eyes
- Paranoid thinking
- A disconnected state (dissociation)
- Increased appetite
Don't drive or operate machinery when using marijuana.
If you have a mental health condition, use marijuana with caution. Marijuana use might worsen manic symptoms in people who have bipolar disorder. If used frequently, marijuana might increase the risk of depression. Marijuana use also might worsen depression symptoms. Research suggests that marijuana use increases the risk of psychosis in people who have schizophrenia.
Smoking marijuana can affect your memory and cognitive function and cause harmful cardiovascular effects, such as high blood pressure. Long-term marijuana use can worsen respiratory conditions.
Marijuana has a central nervous system (CNS) depressant effect. As a result, marijuana use in combination with anesthesia or other drugs used during or after surgery might cause an additive effect. Don't use marijuana two weeks before planned surgery.
Possible interactions include:
- Alcohol. Marijuana use might increase the effects of alcohol.
- Anticoagulants and anti-platelet drugs, herbs and supplements. These types of drugs, herbs and supplements reduce blood clotting. Marijuana might change how the body processes them, possibly increasing the risk of bleeding.
- CNS depressants. Marijuana use in combination with CNS depressants might cause an additive sedative effect.
- Protease inhibitors. Marijuana use with use of these antiviral drugs might reduce their effectiveness.
- Selective serotonin reuptake inhibitors. Mixing marijuana with this type of antidepressant might increase the risk of mania.