Even though the laws are shifting, the debate over legalized marijuana continues. Although some say marijuana is just as safe as, or even safer than, alcohol, others argue that marijuana causes significant harm.
Evidence is limited that occasional use leads to long-term health problems. Still, researchers are concerned that long-term, heavy pot smoking can lead to lingering effects such as lung changes, memory loss and several other health problems.
Your body on marijuana
Marijuana smoke contains about 60 chemicals called cannabinoids; the best-known of these is THC. When you smoke pot, THC and other chemicals travel from your bloodstream to your brain. Some of the other effects you'll feel include:
Trouble thinking and remembering
Bloodshot eyes
Dry mouth (cotton mouth)
Increased appetite (the "munchies")
Fast heart rate
Slowed coordination
Breathing in the smoke
Marijuana smoke is also filled with many of the same chemicals as tobacco smoke, including ammonia, hydrogen cyanide and formaldehyde. Some of these chemicals are known to cause cancer. Most users smoke pot in a joint or water pipe, so they breathe the smoke straight into their lungs.
There's no proof that smoking marijuana causes lung cancer like cigarettes do. But people who smoke pot show signs of damage and precancerous changes in their lungs, especially if they smoke cigarettes. Marijuana smokers often have symptoms like coughing and wheezing.
Effects to the brain
Brain imaging scans of heavy marijuana smokers have revealed changes in blood flow to parts of the brain involved in memory and attention. Researchers have also noted differences in the size and shape of the thalamus, the part of the brain involved in consciousness and information processing. Studies have shown that pot smokers score lower than non-users on memory, attention and learning tests. The more they smoked, the worse they did. And the effects of smoking pot may be even more pronounced in teenage smokers than adults because teens' brains are still developing.
Other health effects
Marijuana can have effects beyond the lungs and brain. These include:
Anxiety
Depression
Fast heart rate
Increased risk of heart attack (within the first hour after smoking)
Suicidal thoughts in teens
Is marijuana addictive?
People who stop smoking pot don't have the same withdrawal symptoms as they might if they were addicted to another drug, such as heroin. Yet those who use marijuana all the time can have a hard time stopping.
Studies show that marijuana dependence does exist. Some long-term, near-daily users seek treatment to quit, yet they keep smoking marijuana, despite its social, psychological and physical effects. They also mention effects such as relationship and family problems, low energy and self-esteem, memory problems and low life satisfaction.
Marijuana can also lead to other addictions, especially in people who start smoking at a young age. That's why it's sometimes called a "gateway drug." One study found that young people who smoke marijuana are more likely to use other drugs, including prescription opioids, in the future.
