Medical Marijuana

Browse By All Topics


Medical Marijuana

Topic Overview

What is medical marijuana and is it legal?

Medical marijuana is the use of this drug to help treat symptoms like pain, nausea, vomiting, and lack of appetite. It's often used by people with cancer, AIDS, multiple sclerosis, epilepsy, and other conditions.

It's against federal law to possess, sell, give away, or grow marijuana for any purpose. It's also against federal law for doctors to prescribe this drug. But more than a dozen states have passed state laws that allow people with certain health problems to buy or grow a limited amount of marijuana for their own use. Some states also allow or license people to provide medical marijuana to those who need it.

If you use medical marijuana to treat approved medical conditions, the federal government might not prosecute you. But there's no guarantee that they won't.

Medical marijuana laws are different from state to state. If you think you might want to try medical marijuana, talk to your doctor. You can also call your state department of health or health services to learn more about the laws in your state.

What do the experts say?

The medical use of marijuana has been studied for decades. But experts still don't agree on how safe it is or how well it works.

Some medical experts don't recommend marijuana because:

  • It hasn't been approved by the Food and Drug Administration.
  • Marijuana smoke, like cigarette smoke, can harm your lungs.
  • Marijuana can harm your memory, judgment, and ability to process information. That can affect your ability to do things like driving a car or studying.
  • There are other legal drugs that may work just as well, such as new kinds of pain and nausea medicines.

Other medical experts sometimes do recommend marijuana because:

  • It can provide pain relief when normal pain medicines don't work or have unwanted side effects.
  • It can improve appetite and relieve nausea in people who have cancer or AIDS.

Be sure to let your doctor know if you are using medical marijuana. If you're pregnant, it's best to avoid alcohol and drugs, including marijuana.

How do you use medical marijuana?

Marijuana is usually smoked. It can also be brewed into tea, vaporized, applied to the skin, or eaten—usually mixed into food recipes.

Your mood, behavior, and ability to function may be affected for hours after you take marijuana. How quickly you feel the effects of marijuana—and how long the effects last—depends on:

  • How much you've taken.
  • How you've taken it.
  • The kind of marijuana you use.
  • How your own body is affected by it.

Side effects include dry mouth, nausea, vomiting, and red eyes.

Is it addictive?

Some people who regularly use marijuana become addicted. This means that they keep using marijuana even though it's having harmful effects on their lives.

If you've been using marijuana regularly and then quit, you may have withdrawal symptoms. These may include:

  • Anxiety.
  • Trouble sleeping.
  • Craving marijuana.

Are there alternatives to medical marijuana?

Doctors can prescribe two legal alternatives: dronabinol (Marinol) and nabilone (Cesamet). Both of these drugs contain a man-made form of THC, the main chemical in marijuana.

Nabilone is used to relieve nausea and vomiting caused by cancer chemotherapy. Dronabinol can relieve this kind of nausea and vomiting too. It may also improve the appetite of people who have AIDS. Both drugs come in pill form.

Talk to your doctor if you think these medicines might help relieve your symptoms.

Is synthetic marijuana safe?

Synthetic marijuana, or synthetic cannabinoids, are sold as substances having effects like those of marijuana. These drugs, sold in the form of bath salts or incense, are made in labs and have many names, such as K2 or Spice. Even though they are labeled "not for human consumption," people are more likely to try them since they are easily bought in stores and online and can't be detected by drug screenings. Also, people think they will feel the same as when they use marijuana. But these drugs are stronger than marijuana, and they are not safer than marijuana. Some people have reported severe symptoms, such as:

  • Faster heart rate and higher blood pressure.
  • Agitation or anxiety.
  • Vomiting.
  • Increased paranoia.
  • Hallucinations.
  • Seizures.


Other Works Consulted

  • Aggarwal SK, et al. (2007). Dosing medical marijuana: Rational guidelines on trial in Washington state. Medscape General Medicine, 9(3): 52. Available online:
  • American Lung Association (2011). Health hazards of smoking marijuana. Available online:
  • American Society of Health-System Pharmacists (2008). Nabilone. Available online:
  • Benson J, et al. (1999). From marijuana to medicine. Issues in Science and Technology. Available online:
  • Fallik D (2010). As another state approves medical marijuana, neurologists urge caution about prescribing. Neurology Today, 10(4): 1, 5–7.
  • Johnson JR, et al. (2010). Multicenter, double-blind, randomized, placebo-controlled, parallel-group study of the efficacy, safety, and tolerability of THC:CBD extract and THC extract in patients with intractable cancer-related pain. Journal of Pain and Symptom Management, 39(2): 167–179.
  • Joy JE, et al., Institute of Medicine (1999). Marijuana and Medicine: Assessing the Science Base. Washington, DC: National Academy Press.
  • National Cancer Institute (2011). Cannabis and Cannabinoids PDQ: Human/Clinical Studies. Available online:
  • National Eye Institute (2009). NEI Statement: Glaucoma and Marijuana Use. Available online:
  • National Institute on Drug Abuse (2010). Marijuana. NIDA InfoFacts. Available online:
  • National Institute on Drug Abuse (2011). Marijuana: Facts for Teens (NIH Publication No. 10-4037). Available online:
  • National Institute on Drug Abuse (accessed June 2011). Is there a link between marijuana use and mental illness? Research Report Series: Marijuana Abuse. Available online:
  • (2011). 16 legal medical marijuana states and DC. Medical Marijuana. Available online:
  • (2011). Medical marijuana: Should marijuana be a medical option? Available online:
  • U.S. Department of Justice (2011). DEA Position on Marijuana. Available online:
  • U.S. Drug Enforcement Administration (accessed June 2011). "Medical" Marijuana—The Facts. Available online:
  • U.S. Food and Drug Administration (2006). Inter-agency advisory regarding claims that smoked marijuana is a medicine. Available online:


ByHealthwise Staff
Primary Medical ReviewerAdam Husney, MD - Family Medicine
Specialist Medical ReviewerTheresa O'Young, PharmD - Clinical Pharmacy
Last RevisedOctober 31, 2011

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use.

How this information was developed to help you make better health decisions.

© 1995-2012 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.