How does marijuana affect health?


Canadian Health Network

Français	Contact Us	Help	Search	Home
About Us	FAQs	Media Room	Site Map	A-Z Index

Groups and Topics

How does marijuana affect health?

Marijuana is the most widely used illegal drug in Canada. About 14% of Canadians over the age of 15 report using it in the last year. It is a mood-altering drug that comes from the Cannabis sativa plant. The effect or "high" in marijuana is caused by the chemical THC (delta-9-tetrahydro-cannabinol). Possessing, producing and trafficking in marijuana can result in fines, prison sentences, and criminal records.

Short-term effects

The effects of smoking marijuana happen quite quickly and last for two to four hours. The effects of eating marijuana occur more slowly and might last for a longer time.

The effects of marijuana depend on the person, the setting, and the amount used. Marijuana can vary widely in the concentration of THC it contains. Some people who use marijuana may feel relaxed and happy. Others may become quiet and withdrawn.

Some of the immediate effects of marijuana are:

forgetfulness

trouble concentrating

slower reactions.

Some users may feel:

severe anxiety

panic attacks

fearful and suspicious (paranoia).

These effects usually disappear within hours.

Driving and operating machinery after using marijuana is NOT safe, especially if combined with other drugs, including alcohol.

Long-term effects

Using marijuana heavily for a long period of time can have serious side effects. Marijuana smoke contains cancer-producing chemicals that damage the lungs and can lead to chronic coughing and lung infections. People who smoke both marijuana and tobacco may develop lung, neck and head cancers at a younger age than those who smoke only tobacco. Heavy marijuana use at a young age may affect brain development, especially in the areas of the brain that control the ability to concentrate attention.

Many long-term users have problems with:

short-term memory

concentration

abstract thinking.

Most of these problems disappear after a few weeks without marijuana, but some last longer.

Medical marijuana

Some people use marijuana for medical reasons, such as to decrease the nausea caused by anti-cancer drugs or, in the case of HIV/AIDS patients, to increase appetite.

Although research hasn't yet shown a clear and unique medical benefit of marijuana, Health Canada implemented regulations in 2001 to govern the possession and production of marijuana for medical purposes.

These regulations outline specific rules for patients and caregivers to possess and cultivate marijuana.

Marijuana and pregnancy

Women who use marijuana during pregnancy are more likely to have premature or underweight babies. As the children grow up, they may have some learning and behavioural problems.

Women who use marijuana while breastfeeding will pass concentrated THC on to their infants through their breast milk.

Marijuana and addiction

Regular users of marijuana develop a tolerance to it, which means that they need to use more of the drug to produce the same effect. Heavy, long-term use of marijuana can cause dependence. Dependent people crave the drug and may have difficulty reducing or stopping their use of it.

Dependent users who quit may feel mild withdrawal symptoms including:

troubled sleep

irritability

anxiety

nausea

sweating

loss of appetite.

These symptoms usually last less than a week, but cravings can last much longer.

For help in your province search the Treatment Services in Canada database produced by the Canadian Centre on Substance Abuse or contact the following agencies:

Alberta
Alberta Alcohol and Drug Abuse Commission

British Columbia
Alcohol and Drug Information and Referral Service

Manitoba
Addictions Foundation of Manitoba