Marijuana
Marijuana is a green, brown or gray mixture of dried, shredded leaves, stems, seeds and flowers of the hemp plant. You may hear marijuana called by street names such as pot, herb, weed, grass, boom, Mary Jane, gangster or chronic. There are more than 200 slang terms for marijuana.
Sinsemilla (sin-seh-me-yah; a Spanish word), hashish (“hash” for short) and hash oil are stronger forms of marijuana.
All forms of marijuana are mind-altering. In other words, they change how the brain works. They all contain THC (delta-9-tetrahydrocannabinol), the main active chemical in marijuana. They also contain more than 400 other chemicals. Marijuana’s effects on the user depend on its strength or potency, which is related to the amount of THC it 
contains. The THC content of marijuana has been increasing since the 1970s.
How is marijuana used?
Marijuana is usually smoked as a cigarette (called a joint or a nail) or in a pipe or a bong. Recently, it has appeared in cigars called blunts.
What happens if you smoke marijuana?
The way the drug affects each person depends on many factors, including:
- user’s previous experience with the drug
- how strong the marijuana is (how much THC it has)
- what the user expects to happen
- where (the place) the drug is used
- how it is taken; and whether the user is drinking alcohol or using other drugs
Some people feel nothing at all when they smoke marijuana. Others may feel relaxed or high. Sometimes marijuana makes users feel thirsty and very hungry—an effect called “the munchies.”
Some users can get bad effects from marijuana. They may suffer sudden feelings of anxiety and have paranoid thoughts. This is more likely to happen when a more potent variety of marijuana is used.
What are the short-term effects of marijuana use?
The short-term effects of marijuana include:
- problems with memory and learning
- distorted perception (sights, sounds, time, touch)
- trouble with thinking and problem solving
- loss of motor coordination; and increased heart rate
These effects are even greater when other drugs are mixed with the marijuana, and users do not always know what drugs are given to them.
What are the long-term effects of marijuana use?
Findings so far show that regular use of marijuana or THC may play a role in some kinds of cancer and link to problems with the respiratory and immune systems.
Cancer
It’s hard to know for sure whether regular marijuana use causes cancer, but it is known that marijuana contains some of the same, and sometimes even more, of the cancer-causing chemicals found in tobacco smoke. Studies show that someone who smokes five joints per day may be taking in as many cancer-causing chemicals as someone who smokes a full pack of cigarettes every day.
Lungs and airways
People who smoke marijuana often develop the same kinds of breathing problems that cigarette smokers have: coughing and wheezing. They tend to have more chest colds than nonusers. They are also at greater risk of getting lung infections like pneumonia.
Immune system
Animal studies have found that THC can damage the cells and tissues in the body that help protect against disease. When the immune cells are weakened, you are more likely to get sick.
What does marijuana do to the brain?
Some studies show that when people have smoked large amounts of marijuana for years, the drug takes its toll on mental functions. Heavy or daily use of marijuana affects the parts of the brain that control memory, attention and learning. A working short-term memory is needed to learn and perform tasks that call for more than one or two steps.
Smoking marijuana causes some changes in the brain that are like those caused by cocaine, heroin and alcohol. Scientists are still learning about the many ways that marijuana can affect the brain.
Can people become addicted to marijuana?
Long-term marijuana use can lead to addiction in some people. That is, they cannot control their urges to seek out and use marijuana, even though it negatively affects their family relationships, school performance and recreational activities. According to one study, marijuana use by teenagers who have prior antisocial problems can quickly lead to addiction. In addition, some frequent, heavy marijuana users develop “tolerance” to its effects. This means they need larger and larger amounts of marijuana to get the same desired effects as they used to get from smaller amounts, which can also lead to an addiction.
