Cannabis is usually consumed by smoking or eating. Smoking gives a faster high (within minutes) and lasts for 1-3 hours but similar to cigarettes, smoking cannabis may damage the lungs over time. Eating foods with cannabis in them gives a delayed high (usually about an hour) but one that can linger slightly (up to 4 hours).
After using cannabis (it is typically smoked), the THC is absorbed into the bloodstream and it travels to the brain. Here the THC will bind to specific receptors, called cannabinoid receptors. This binding reaction in the brain is what produces the “high” and the resulting effects felt by the user. These receptors change over time with regular cannabis use.
THC is stored in fat cells. It takes a long time to completely clear from the body. Also, because women, in general, have more fatty tissue than men, women take longer than men to clear THC.
The half life of THC in the body (this is the time to remove half of the amount that you absorbed) is estimated to be 7 days. It may take multiple half lives to remove all of the THC in your body. In typical users this means that while you may not still be experiencing the psychoactive effects (which alter the mind, mood or mental processes); you can still have a positive drug test long after the drug has been taken and the effects have worn off. This may be important for you if your job requires you to be abstinent or if you are crossing some country borders such as the US-Canada border.