depends, less than a month, but if you push liquids you can flush it out in under a week.
There are no absolute proven facts about the long-term effects of marijuana. The obvious short-term effects are memory loss, euphoria, slow reaction time (which is why you should not drive under the influence of any drug), forgetfulness, laughing when nothing is funny, etc. But there are proven facts that show that cannabis has healing properties, such as pain management. To find out more about long and short term effects, I suggest going to www.google.com for research. But I warn you, there are so many conflicting viewpoints that you may get confused. You will just have to come up with your own theory.
The time that marijuana stays in your system varies on how much you smoke, how many times you've smoked in the past, your metabolism, body weight, daily exercise ect. But the reason that it takes awhile for THC to get out of your system is because THC is stored in fat cells and it takes awhile to burn fat. People say that it's only in your blood stream and if you drink alot of water your body will dispose of it but to tell you the truth that doesnt work as well as it sounds. All drinking water does is cleans out the remote THC that hasn't attached to a fat cell yet. So if you want to clean your system fast eat alot of red meats, drink water, do lots of exercise ect.
Everyone is really over complicating this.
The answer everyone's looking for actually quite obvious.
It stay's in your system because, brace yourself, IT'S HEALTHY!
Your body isn't trying to get rid of it!
Like a manufactured chemical or a drug.
According to the website of Columbia University's Health Services:
Marijuana itself does not "stay" in your system, but the main chemical in marijuana, THC, does. It fact, it may stay in your system forever because it is stored in fatty tissues of various organs.
Despite being stored in body fat, THC is only detectable for a certain amount of time. Many drug tests, including urine tests, look for 9-carboxy-THC which is the by-product of your body metabolizing the THC in your fat.
Marijuana Detection TimesFrequent users blood drug test (defined as someone who smokes several times per week)
THC: 4-8 hours after smoking
THC by-product: 2 or more weeks after smoking
Frequent users urine drug test
THC by-product: 2 weeks to a month after smoking (3 months for extremely heavy users)
Infrequent users blood drug test
THC: 3-4 hours after smoking
THC by-product: 2-3 days after smoking
Infrequent users urine drug test
THC by-product: up to 10 days after smoking