HEALTH

420: A Q&A on Marijuana by the National Institute on Drug Abuse

Marijuana plants flourish under grow lights at a warehouse in Denver on Tuesday, Oct. 26, 2010. More than 40 Colorado jurisdictions considering local rules on medical marijuana this election. Thanks to a new state law allowing local governments more leeway in regulating pot, voters across the state will consider proposed bans on dispensaries or commercial pot-growing operations.  (AP Photo/Ed Andrieski)

Marijuana plants flourish under grow lights at a warehouse in Denver on Tuesday, Oct. 26, 2010. More than 40 Colorado jurisdictions considering local rules on medical marijuana this election. Thanks to a new state law allowing local governments more leeway in regulating pot, voters across the state will consider proposed bans on dispensaries or commercial pot-growing operations. (AP Photo/Ed Andrieski)

Today is National Marijuana Day, so we are running a Q & A by the National Institute on Drug Abuse about the health effects of pot.

Q: What happens after a person smokes marijuana?

A: Within a few minutes of inhaling marijuana smoke, the user will likely feel, along with intoxication, a dry mouth, rapid heartbeat, some loss of coordination and balance, and a slower than normal reaction time. Blood vessels in the eye expand, so the user’s eyes look red.

For some people, marijuana raises blood pressure slightly and can double the normal heart rate. This effect can be greater when other drugs are mixed with marijuana, but users do not always know when that happens.

As the immediate effects fade, usually after 2 to 3 hours, the user may become sleepy.

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Q: How long does marijuana stay in the user's body?

A: THC in marijuana is readily absorbed by fatty tissues in various organs. Generally, traces (metabolites) of THC can be detected by standard urine testing methods several days after a smoking session. In heavy, chronic users, however, traces can sometimes be detected for weeks after they have stopped using marijuana.

Q: Can a user have a bad reaction?

A: Yes. Some users, especially those who are new to the drug or in a strange setting, may suffer acute anxiety and have paranoid thoughts. This is more likely to happen with high doses of THC. These scary feelings will fade as the drug’s effects wear off.

In rare cases, a user who has taken a very high dose of the drug can have severe psychotic symptoms and need emergency medical treatment.

Other kinds of bad reactions can occur when marijuana is mixed with other drugs, such as PCP or cocaine.

Q: How is marijuana harmful?

A: Marijuana can be harmful in a number of ways, through immediate effects and through damage to health over time.

Marijuana hinders the user’s short-term memory (memory for recent events), and he or she may have trouble handling complex tasks. With the use of more potent varieties of marijuana, even simple tasks can be difficult.

Because of the drug’s effects on perceptions and reaction time, users could be involved in auto crashes. Drug users also may become involved in risky sexual behaviors, which could lead to the spread of HIV, the virus that causes AIDS.

Under the influence of marijuana, students may find it hard to study and learn. Young athletes could find their performance is off; timing, movements, and coordination are all affected by THC.

Q: What are the long-term effects of marijuana?

A: Although all of the long-term effects of marijuana use are not yet known, there are studies showing serious health concerns. For example, a group of scientists in California examined the health status of 450 daily smokers of marijuana, but not tobacco. They found that the marijuana smokers had more sick days and more doctor visits for respiratory problems and other types of illness than did a similar group who did not smoke either substance.

Findings so far show that the regular use of marijuana may play a role in cancer and problems of the immune and respiratory systems.

Cancer

It is hard to find out whether marijuana alone causes cancer, because many people who smoke marijuana also smoke cigarettes and use other drugs. Marijuana smoke contains some of the same cancer-causing compounds as tobacco, sometimes in higher concentrations. 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.

Tobacco smoke and marijuana smoke may work together to change the tissues lining the respiratory tract. Marijuana smoking could contribute to early development of head and neck cancer in some people.

Immune system

Our immune system protects the body from many agents that cause disease. It is not certain whether marijuana damages the immune system of people. But both animal and human studies have shown that marijuana impairs the ability of T-cells in the lungs’ immune system to fight off some infections.

Lungs and airways

People who smoke marijuana regularly may develop many of the same breathing problems that tobacco smokers have, such as daily cough and phlegm production, more frequent chest colds, a heightened risk of lung infections, and a greater tendency toward obstructed airways. Marijuana smokers usually inhale more deeply and hold their breath longer, which increases the lungs’ exposure to toxic chemicals and irritants.

Source: National Institute on Drug Abuse