How long do the effects of marijuana last?

Answer 1

The affects of cannabis, notably the euphoria or "high" feeling lasts for up to 8 hours. THC is quickly metabolized by the body and has a high affinity for CB1 receptors in the brain. A common misconception is that THC is stored in the body's fat cells and that when a drug test is taken, the drug test is detecting THC. The reality is that only THC metabolites - the byproducts of THC breakdown - are stored in the body's fat cells. Drug tests seek to detect THC metabolites. One can not get high from the metabolites. THC metabolites can be detected in the body for as long as 8 weeks depending on how often one smokes, one's body fat percentage, kidney functions, etc. Essentially if one smokes only occasionally, the metabolites will only be detectable for a very short time, as long as 2 weeks. A heavy smoker will have metabolites in their system for much longer, up to 3 months.

Cognitive Abilities (memory, executive functioning, motor control, concentration) are only affected for the duration of intoxication. If someone smokes a joint and does not use cannabis after that, they will only be under the effects for about 8 hours. Short term memory is unaffected after intoxication ends. The long term affects of cannabis on memory are not well established or studies. There may be some mild short term memory loss. Long term memory does not seem to be affected. Learning does not seem to be affected when not intoxicated. There is even evidence that Cannabis offers beneficial neuro-protective effects. THC/CBD has been shown to decrease the amount of beta-amyloid plaques in Alzheimer's patients. There is a study that has shown that THC helps promote neuronal re-growth, and decreases anxiety and depression. The U.S. government even holds a patent showing that THC, the active component in Cannabis has a positive effect on the human brain.

There is some concern that smoking cannabis may lead to cancer. At least one study has shown this may not be the case. In this study tobacco smokers, cannabis smokers, and smokers of both were studied. Tobacco smokers had a higher rate of cancer than the other two categories. Smokers of both only had a slightly higher rate of developing cancer than those who only smoked cannabis. The incidence of cancer in those who smoked cannabis was so low that it could not be causally linked.

As a note: The author of this answer is currently has a Bachelors of Science in Psychology with a heavy emphasis on drugs, brain, and behavior. The author has also advanced to candidacy in a Clinical Psychology doctoral program that also emphasizes neuropsychopharmacology (i.e. Drugs, Brain, and Behavior).

Answer 2

The effects of marijuana can last anywhere from 1 to 3 hours after consumption, but this can vary depending on factors such as dosage, method of consumption, and individual tolerance levels. Impairment from marijuana can linger for several hours after the initial effects wear off.