What the research says

Research on the use of marijuana for specific conditions shows:

• Glaucoma. Some studies show that cannabis lowers blood flow to the nerve that helps people see. This could raise the risk of vision changes in people with an eye disease that damages the nerve to the eyes, called glaucoma. But cannabis might lower the higher eye pressures this eye condition causes, which could be helpful. The effect doesn't seem to last more than a few hours. It likely doesn't work as well as other glaucoma treatments.
• Nausea and vomiting related to cancer treatment. Research has shown that THC helps lessen nausea and vomiting in people receiving chemotherapy. If standard medicines for nausea don't work, using THC products may help some people.
• Pain. Cannabis might lower the intensity of shooting or burning pain often due to nerve damage. This type of pain is known as neuropathic pain. People with conditions such as HIV and diabetes may have this type of pain.
• Seizures. It's not clear whether cannabis can treat seizures. Some people with conditions that cause childhood seizures, such as Lennox-Gastaut syndrome or Dravet syndrome, may take a prescription form of cannabidiol, also called CBD, by mouth to treat seizures.
• Spasticity. Cannabis may help treat muscle movements a person can't control in people with multiple sclerosis. These movements are called spasms. Most studies looked at a pill form of a chemical in cannabis, not cannabis that is smoked.
• Cancer treatment. Some people use cannabis to treat their cancers. Some studies on animals show promise. There are no large studies that show that cannabis helps treat cancer. More research is needed.