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Medical marijuana is now legal in a majority of states. A small but growing number of states and cities have legalized recreational pot as well. Marijuana still is the most commonly used illegal drug in the U.S. Marijuana has some well-proven benefits, including relief for long-term pain. But smoking marijuana can have some bad effects on your health, including making breathing problems worse.The federal ban on marijuana makes it hard to study its effects on humans. For example, very little research exists on edible marijuana.
Key Chemicals
Marijuana comes from the dried flowers of the plant Cannabis sativa. It has more than 500 chemicals. Cannabis can have a psychoactive -- or mind-altering -- effect on you.THC: This is the main psychoactive agent in marijuana. Its full name is delta 9-tetrahydrocannabinol. When you smoke cannabis, THC goes from your lungs into your bloodstream and then into your brain. It stimulates the part of your brain that responds to sources of pleasure, like food and sex. That lets loose a chemical called dopamine, which causes the high.