Marijuana—also called weed, herb, pot, grass, bud, ganja, Mary Jane, and a vast number of other slang terms—is a greenish-gray mixture of the dried, shredded leaves and flowers of Cannabis sativa— the hemp plant.
Smoking pot can increase your heart rate by as much as two times for up to 3 hours. That’s why some people have a heart attack right after they use marijuana. It can increase bleeding, lower blood pressure, and affect your blood sugar, too.
We don’t yet know if marijuana is linked to higher odds of getting lung cancer. But the process does irritate your lungs -- which is why regular pot smokers are more likely to have an ongoing cough and to have lung-related health problems like chest colds and lung infections.
Other physical effects of marijuana include:
Dizziness
Shallow breathing
Red eyes and dilated pupils
Dry mouth
Increased appetite
Slowed reaction time (If you drive after using marijuana, your risk of being in a car accident more than doubles.)
If you’re a long-time user, you can have physical withdrawal symptoms -- like cravings, irritability, sleeplessness, and less appetite -- when you stop.
Marijuana remains the most abused illegal substance among youth. By the time they graduate high school, about 46 percent of U.S. teens will have tried marijuana at least once in their lifetime. Although use among teens dropped dramatically in the previous decade (to a prevalence of about 12.4 percent for past-month use in 2007), adolescent marijuana use is again on the upswing. In 2013, nearly 23 percent of high school seniors were current marijuana users, and 6.5 percent used marijuana daily. The annual Monitoring the Future survey, which has been tracking teen attitudes and drug use since 1975, shows that use of marijuana over time is directly related to how safe teens perceive the drug to be; currently the number of teens who think marijuana users risk harming themselves is declining. This, despite growing scientific evidence that marijuana use during the teen years can permanently lower a person’s IQ and interfere with other aspects of functioning and well-being.
Marijuana also affects brain development. When marijuana users begin using as teenagers, the drug may reduce thinking, memory, and learning functions and affect how the brain builds connections between the areas necessary for these functions.
Marijuana’s effects on these abilities may last a long time or even be permanent.
For example, a study showed that people who started smoking marijuana heavily in their teens and had an ongoing cannabis use disorder lost an average of eight IQ points between ages 13 and 38. The lost mental abilities did not fully return in those who quit marijuana as adults. Those who started smoking marijuana as adults did not show notable IQ declines (Meier, 2012).