Medical marijuana

U.S. federal law doesn’t allow the use of marijuana. But many states allow medical use to treat pain, nausea and other symptoms.

By Mayo Clinic Staff

Medical marijuana comes from the Cannabis sativa plant. It’s used to ease symptoms caused by certain medical conditions. Medical marijuana also is called medical cannabis.

Cannabis sativa has chemicals called active compounds. They act in the body in ways that may ease certain symptoms. The best known are delta-9 tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is the part of marijuana that acts on the brain and affects mood, behavior and thoughts, called psychoactive.

Is medical marijuana legal in the U.S.?

U.S. federal law does not allow the use of whole plant Cannabis sativa or its parts for any purpose. But CBD from the hemp plant is legal under federal law. It has less than 0.3% THC.

Many states allow THC to be used for medical reasons. Healthcare professionals in those states can suggest medical marijuana, what dose to take and what type to use. But they can’t prescribe it.

But federal laws about marijuana outweigh state laws. Because of this, people may be arrested and charged with having marijuana, called possession, even in states where marijuana use is legal.

What is medical marijuana used for?

Studies report that medical cannabis might help some conditions. Which conditions medical marijuana can treat varies by state. If you’re thinking of marijuana for medical use, check your state’s laws.

Whether you can get medical marijuana to treat a condition you have depends on the state. Conditions some states cover include:

  • Alzheimer’s disease.
  • Amyotrophic lateral sclerosis (ALS).
  • Crohn’s disease.
  • Epilepsy and seizures.
  • Glaucoma.
  • Multiple sclerosis and muscle spasms.
  • Posttraumatic stress disorder.
  • Serious and ongoing pain.
  • Serious nausea or vomiting caused by cancer treatment.

Is medical marijuana safe?

More study is needed to answer this question. But side effects of medical marijuana may include:

  • Increased heart rate.
  • Dizziness.
  • Problems with thinking and memory.
  • Slower reaction times.
  • Interactions with other medicines.
  • Increased risk of heart attack and stroke.
  • Panic attacks.
  • Getting addicted.
  • Seeing or hearing things that aren’t there, called hallucinations, or mental illness.
  • Withdrawal symptoms.
  • Early labor and other complications in people who are pregnant.

Is medical marijuana available as a prescription medicine?

The U.S. Food and Drug Administration (FDA) has not approved the use of cannabis as a treatment for any medical condition. But the FDA has approved the cannabinoids cannabidiol (Epidiolex), which comes from the cannabis plant, and dronabinol (Marinol, Syndros), which is human made, called synthetic.

Cannabidiol can be used for certain forms of epilepsy. Dronabinol can be used for nausea and vomiting caused by cancer treatment and for not wanting to eat, called anorexia, linked to weight loss in people with AIDS.

What you can expect

Forms of taking medical marijuana include:

  • Inhaled. This involves dried cannabis flower in a cigarette, pipe or vape device.
  • Eaten. This comes in capsules, chewable candies called gummies and baked goods.
  • Put under the tongue or on the mucus membranes of the mouth. This is a liquid or spray.
  • Rectally. This comes in the form of a suppository that’s put into the rectum.
  • Topical. This goes on the skin in the form of a lotion or gel.

How and where you buy medical marijuana depends on the state you live in. How often you use it depends on its form and your symptoms. In states where medical marijuana is legal, your healthcare professional can suggest types and doses.

Your symptom relief and side effects depend on which type of medical marijuana you use. Inhaling marijuana vapor acts the quickest. Pills are the slowest to give relief.

Certification and use at Mayo Clinic


Mayo Clinic healthcare providers may certify state residents with qualifying conditions in the Minnesota medical cannabis program. However, not all Mayo Clinic providers are registered for the certification process in Minnesota.

Minnesota residents with a supply of medical cannabis from a Cannabis Patient Center may keep using their supply during their Mayo Clinic visit or hospital stay.

Arizona and Florida

Mayo Clinic campuses in Arizona and Florida do not certify people for medical marijuana or allow its use on campus or in the hospital.


Arizona Department of Health Services: Medical marijuana

Florida Health: Office of Medical Marijuana Use

Minnesota Department of Health: Medical cannabis

National Conference of State Legislatures: State medical marijuana laws

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May 30, 2024

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