What happens to your body when you use marijuana?

Within a few minutes after inhaling marijuana smoke, a person’s heart rate speeds up, the bronchial passages (the pipes that let air in and out of your lungs) relax and become enlarged, and blood vessels in the eyes expand, making the eyes look red. While these and other effects seem harmless, they can take a toll on the body.

Short-Term Effects

Short term effects include:

  • altered senses (such as seeing brighter colors)
  • altered sense of time
  • changes in mood
  • slow reaction time
  • problems with balance and coordination
  • increased appetite
  • trouble thinking and solving problems
  • memory problems
  • hallucinations (seeing things that aren’t really there)
  • delusions (believing something that is not true)
  • psychosis (having false thoughts) (risk is highest with regular use of high potency marijuana)

Mixing marijuana with alcohol can cause increased heart rate and blood pressure. It can also cause further slowing of the ability to think, solve problems, and react.

Long-Term Effects

  • Increased heart rate. When someone uses marijuana, the heart rate (normally 70 to 80 beats per minute)—may increase or even double,   especially if other drugs are taken with the marijuana. This increases the risk of a heart attack.
  • Respiratory (lung and breathing) problems. Smoke from marijuana irritates the lungs, and can cause a chronic cough—effects similar to those from regular cigarettes. While research has not found a strong association between marijuana and lung cancer, many people who smoke marijuana also smoke cigarettes, which do cause cancer.
  • Increased risk for mental health problems. Marijuana use has been linked with depression and anxiety, as well as suicidal thoughts among teens. In addition, research suggests that smoking marijuana during the teen years might increase the risk for developing psychosis in people with a genetic risk for developing schizophrenia. Researchers are still studying the relationship between these mental health problems and marijuana use.
  • Increased risk of problems for an unborn baby. Marijuana use during pregnancy is linked to lower birth weight and increased risk of behavioral problems in babies.2

2 The National Academies of Sciences, Engineering, and Medicine, Health and Medicine Division, Board on Population Health and Public Health Practice, Committee on the Health Effects of Marijuana: An Evidence Review and Research Agenda. The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research. Washington, DC, January 12, 2017. Available at http://nationalacademies.org/hmd/Reports/2017/health-effects-of-cannabis-and-cannabinoids.aspx