Is medical marijuana safe?

Further study is needed to answer this question, but possible short- and long-term risks of using marijuana to treat medical conditions include:

  • Addiction, which occurs in about 10 percent of users who start smoking marijuana before age 25
  • Breathing problems, for people who smoke marijuana
  • Dizziness
  • Impaired concentration and memory
  • Increased heart rate
  • Increased risk of heart attack or stroke
  • Mental illness in people with a tendency toward it
  • Negative drug-to-drug interactions
  • Slower reaction times
  • Withdrawal symptoms

Is medical marijuana available as a prescription medicine?

The Food and Drug Administration (FDA) has approved two drugs made from synthetic forms of ingredients found in marijuana: dronabinol (Marinol, Syndros) and nabilone (Cesamet). These medicines are made from synthetic forms of certain ingredients in marijuana.

They can be legally prescribed for the treatment of nausea and vomiting caused by chemotherapy when other treatments have failed. Dronabinol may also be used for the treatment of anorexia associated with weight loss in people with AIDS.

The FDA has also approved two clinical research projects for new forms of marijuana ingredients.

What you can expect

Medical marijuana comes in a variety of forms, including:

  • Oil
  • Pill
  • Vaporized liquid
  • Nasal spray
  • Dried leaves and buds
  • Plant

How and where you purchase these substances legally varies among the states that allow medical use of marijuana. Once you have the product, you administer it yourself. How often you use it depends on its form and your symptoms.

Your symptom relief and side effects also will vary. You may notice the marijuana taking effect in 30 minutes or hours. The extent and timing of its effects may be harder to control with the pill form than with smoking.

Some medical marijuana is formulated to provide symptom relief without the intoxicating, mood-altering effects associated with recreational use of marijuana.

Certification and use at Mayo Clinic

Arizona, Florida and Minnesota have adopted some form of the Right to Try Act for terminal patients, which provides for early access to investigational treatments, including possibly marijuana. The Right to Try Act typically does not limit in-state use to in-state residents only. Statements below do not apply to Right to Try situations.


In Arizona, medical marijuana is legal as plant material to smoke. Mayo Clinic campuses in Arizona do not dispense medical marijuana, certify people for using it, or allow its use on campus or in the hospital.


Florida law permits qualified physicians to order low-THC cannabis or medical cannabis for patients diagnosed with certain conditions. Patients must be Florida residents to be eligible to participate. Mayo Clinic campuses cannot dispense medical marijuana and do not allow its use on campus or in the hospital at this time.


Iowa allows people to be registered in a medical marijuana program by a physician licensed in Iowa. But it has no state-authorized dispensing sites. Mayo Clinic doctors in Iowa can register patients for the Minnesota medical marijuana program only if the doctor is also licensed in Minnesota and is part of that state's Department of Health registry; the patient is a Minnesota resident and part of the state's registry; and the patient does not transport marijuana across state lines (still a federal offense).


In Minnesota, medical cannabis is available as pills, oils and liquids at state-designated dispensaries. It is not available at pharmacies or through a prescription from a doctor. To receive medical cannabis from a dispensary, Minnesota residents with qualifying conditions need to register with the Minnesota Department of Health. As part of the registration process, a physician, physician assistant or advanced practice registered nurse (APRN) must certify that you have a qualifying medical condition.

Mayo Clinic practices in Minnesota may certify Minnesota residents with qualifying conditions in the Minnesota medical cannabis program. Not all Mayo Clinic health care providers will be registered for the certification process in Minnesota. Rochester has one of several approved medical cannabis dispensing sites in Minnesota. Others are in Eagan, Hibbing, Eden Prairie, Minneapolis, Moorhead, St. Cloud and St. Paul.


In Wisconsin, marijuana for medical use is not legal.


  1. Arizona Department of Health Services: Medical marijuana
  2. Florida Health: Office of Compassionate Use
  3. Minnesota Department of Health: Medical cannabis
  4. National Conference of State Legislatures: State medical marijuana laws
Oct. 14, 2016 See more In-depth