Questions remain about the medical effectiveness of marijuana


California is among a growing number of states that have legalized marijuana for medicinal purposes. The state recently legalized recreational marijuana as well. The U.S. Food and Drug Administration (FDA) has now approved three drugs that contain marijuana compounds (cannabinoids).

These drugs offer the hope of relief for some patients, such as people who don’t respond to conventional treatments for advanced Alzheimer’s disease or cancer. But questions remain about the medical role they can and should play.

There is evidence to support that cannabinoids are effective for treating:

  • Chemotherapy-induced nausea and vomiting
  • Weight loss associated with advanced stages of illnesses such as HIV or cancer
  • Pain, especially nerve pain
  • Epilepsy in children

There is little high-quality evidence that it can treat:

  • Insomnia
  • Anxiety
  • Multiple sclerosis
  • Neurodegenerative diseases

Doctors want to improve their understanding of cannabinoids

While the FDA has approved the limited use of marijuana, the U.S. Drug Enforcement Administration (DEA) still classifies it as an addictive and dangerous substance with no medical value. This status makes it hard for researchers to perform high-quality studies. In particular, doctors want to understand the 400 to 500 chemical compounds found in whole-leaf cannabis because it is the form most people use.

Before prescribing cannabinoids, doctors identify the risks and benefits for the patient. Risks may outweigh benefits for young people whose brains are still developing. Risks for this population include:

  • Effects on memory and cognition
  • Decreased motivation
  • The potential to speed up or worsen psychiatric disorders in patients who are prone to them. The onset of schizophrenia and bipolar disorder, for example, frequently occurs from late teens to mid-20s.

UCLA Health is studying cannabinoids and their medical effectiveness through the UCLA Cannabis Research Initiative. Subscribe to our newsletter to receive updates on research, news and events.