Marijuana, which comes from the hemp plant Cannabis sativa, is the most frequently used illegal drug in the whole world. About 4% of American adults smoke weed at least once a year. Roughly 1% of adults abuse cannabis, and one in 300 have a marijuana addiction. Most people smoke the plant's dried leaves, flowers, stems, and seeds. But marijuana also can be mixed into food or brewed as a tea. Marijuana goes by many street names, including ganja, pot, igbo, weed, and herb. Hash, a concentrated form of the drug, is short for hashish. The rates of marijuana smoking in adults have remained stable since the 1990s. However, the rates of addiction to marijuana have risen significantly over that same period. And, according to recent government studies, as many as 30% of today's teenagers are smoking marijuana. Occasional marijuana use is rarely seriously harmful, but smoking it has important medical effects.

Physiological Effects of Marijuana
The active ingredient in marijuana is THC. That's short for delta-9-tetrahydrocannabinol.THC is rapidly absorbed after smoking pot. Within minutes, THC and the other substances in marijuana smoke cause short-term medical effects.
Signs of using marijuana include:
Rapid heart rate
Increased blood pressure
Increased rate of breathing
Red eyes
Dry mout
Increased appetite, or "the munchies"Slowed reaction time
These effects are reduced after three or four hours. However, marijuana hangs around in your system for as long as a month after smoking. The lingering effects mean you're impaired for several days to weeks after the high wears off.

Psychological Effects of Marijuana
According to the National Institute on Drug Abuse, the main effects of marijuana on mood vary and may include euphoria, calmness, anxiety, or paranoia. Getting high or "stoned" is the reason most pot smokers use marijuana. Other short-term psychological effects of pot include: Distorted sense of time, Paranoia Magical or "random" thinking, Short-term memory loss, Anxiety and depression, These psychological signs of using cannabis also generally ease after a few hours. But residual effects can last for days.

Risks of Marijuana Use
The risks of smoking marijuana go up with heavy use. Although the link has never been proven, many experts believe heavy pot smokers are at increased risk for lung cancer.
Heavy marijuana use lowers men's testosterone levels and sperm count and quality. Marijuana could decrease libido and fertility in some heavy-smoking men.
Contrary to what many weed smokers may tell you, marijuana is addictive, at least psychologically.
Even among occasional users, one in 12 can feel withdrawal symptoms if they can't get high when they want to. Among heavy pot smokers, the rates of dependence are higher.
Many experts also believe that marijuana is physically addictive. Symptoms of withdrawal from pot might include: Aggression, Anxiety, Depressed mood, Decreased appetite. Is weed a "gateway" drug? In other words, does smoking marijuana make someone more likely to try cocaine, heroin,ecstasy, and other "hard" drugs? The jury is still out on this one. It's true that pot smokers are more likely to use other drugs after trying marijuana. What's not clear is whether smoking cannabis causes further drug use or if people who start smoking pot are just more likely to try drugs in general. If you're wondering how long marijuana stays in your system after smoking, it depends on how often you smoke. Light users -- those who smoke pot once in a while -- will have a negative drug screen after a marijuana-free week. Heavy users -- sometimes called "stoners" -- may continue testing positive for a month after last smoking marijuana.
Stay free from drugs and be guided.