Marijuana is a controlled substance in the U.S. Federal law prohibits its use for any reason. Many states, however, allow medical use of marijuana to treat pain, nausea and other symptoms.

By Mayo Clinic Staff

Medical marijuana — also called medical cannabis — is a term for derivatives of the Cannabis sativa plant that are used to relieve serious and chronic symptoms.

Cannabis sativa contains many active compounds, but two are of interest for medical purposes: THC (delta-9 tetrahydrocannabinol) and CBD (cannabidiol). THC is the primary ingredient in marijuana that makes people "high."

U.S. federal law prohibits the use of whole plant Cannabis sativa or its derivatives for any purpose. CBD derived from the hemp plant (< 0.3% THC) is legal under federal law to consume.

Many states allow THC use for medical purposes. Federal law regulating marijuana supersedes state laws. Because of this, people may still be arrested and charged with possession in states where marijuana for medical use is legal.

Studies report that medical cannabis has possible benefit for several conditions. State laws vary in which conditions qualify people for treatment with medical marijuana. If you're considering marijuana for medical use, check your state's regulations.

Depending on the state, you may qualify for treatment with medical marijuana if you meet certain requirements and have a qualifying condition, such as:

  • Alzheimer's disease
  • Amyotrophic lateral sclerosis (ALS)
  • HIV/AIDS
  • Cancer
  • Crohn's disease
  • Epilepsy and seizures
  • Glaucoma
  • Multiple sclerosis and muscle spasms
  • Severe and chronic pain
  • Severe nausea

If you are experiencing uncomfortable symptoms or side effects of medical treatment, especially pain and nausea, talk with your doctor about all your options before trying marijuana. Doctors may consider medical marijuana as an option if other treatments haven't helped.

Further study is needed to answer this question, but possible side effects of medical marijuana may include:

  • Increased heart rate
  • Dizziness
  • Impaired concentration and memory
  • Slower reaction times
  • Negative drug-to-drug interactions
  • Increased risk of heart attack and stroke
  • Increased appetite
  • Potential for addiction
  • Cyclic vomiting syndrome
  • Hallucinations or mental illness
  • Withdrawal symptoms

The U.S. Food and Drug Administration (FDA) has approved one cannabis-derived and three cannabis-related drugs: dronabinol (Marinol, Syndros), nabilone (Cesamet) and cannabidiol (Epidiolex).

Dronabinol and nabilone can be prescribed for the treatment of nausea and vomiting caused by chemotherapy and for the treatment of anorexia associated with weight loss in people with AIDS. Cannabidiol can be prescribed for treatment of severe forms of childhood epilepsy.

Medical marijuana comes in a variety of forms, including:

  • Oil for vaporizing
  • Pill
  • Topical applications
  • Oral solution
  • Dried leaves and buds

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 based upon which type you are using. The quickest effects occur with inhalation of the vaporized form. The slowest onset occurs with the pill form.

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

Nov. 27, 2019