Medical Marijuana

From the WebMD Archives

More states are passing laws that allow people to use medical marijuana. So what does it treat, and who can and should use it?

Pain is the main reason people ask for a prescription, says Barth Wilsey, MD, a pain medicine specialist at the University of California Davis Medical Center. It could be from headaches, a disease like cancer, or a long-term condition, like glaucoma or nerve pain.

If you live in a state where medical marijuana is legal and your doctor thinks it would help, you’ll get a “marijuana card.” You will be put on a list that allows you to buy marijuana from an authorized seller, called a dispensary.

Doctors also may prescribe medical marijuana to treat:

The FDA has also approved THC, a key ingredient in marijuana, to treat nausea and improve appetite. It's available by prescription Marinol (dronabinol) and Cesamet (nabilone).

How Does It Work?

Your body already makes marijuana-like chemicals that affect pain, inflammation, and many other processes. Marijuana can sometimes help those natural chemicals work better, says Laura Borgelt, PharmD, of the University of Colorado.

How Is It Used?

Medical marijuana may be:

  • Smoked
  • Vaporized (heated until active ingredients are released, but no smoke is formed)
  • Eaten (usually in the form of cookies or candy)
  • Taken as a liquid extract

Side Effects

Side effects of marijuana that usually don’t last long can include:

More serious side effects include severe anxiety and psychosis.

Risks and Limits

Medical marijuana is not monitored like FDA-approved medicines. When using it, you don’t know its potential to cause cancer, its purity, potency, or side effects.

Only people who have a card from a doctor should use medical marijuana. Doctors will not prescribe medical marijuana to anyone under 18. Others who should not use it:

WebMD Feature Reviewed by Arefa Cassoobhoy, MD, MPH on November 04, 2013

Sources

SOURCES:

Barth Wilsey, MD, associate physician, Department of Medicine & Physical Rehabilitation, University of California Davis Medical Center.

Laura Borgelt, PharmD, associate professor, Departments of Clinical Pharmacy and Family Medicine, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado.

Zajicek, J.P. Journal of Neurology, Neurosurgery, and Psychiatry, November 2012.

Slatkin, N.E. Journal of Supportive Oncology, May 2007.

Walsh, Z. International Journal of Drug Policy, Sept. 9, 2013.

Department of Justice Fact Sheet.

Igor Grant, MD, professor and executive vice-chair of the Department of Psychiatry at the University of California, San Diego School of Medicine; director of the HIV Neurobehavioral Research Program.

Tashkin, David P. Annals of the American Thoracic Society, June 2013.

Grotenhermen, F. Deutsches Artzeblatt International.,July 2012.

Wang, T. Canadian Medical Association Journal, June 2008.

Callaghan, R.C. Cancer Causes Control, October 2013.

Wang, G.S. JAMA Pediatrics, July 2013.

American Journal of  Psychiatry, 2012.

© 2013 WebMD, LLC. All rights reserved.