Marijuana is the most commonly used and tested for illicit drug in the United States. There is no simple and accurate answer to the question "how long does THC stay in the body?". THC can remain in the body and its metabolites can be detected by many drug tests from 3 to 90 days after it is ingested orally or smoked. Many factors go into determining how long drug toxins will remain in a person's body; these factors vary from person to person and include the analytical method used to detect the drug, your overall health, your body weight and body fat percentage, your metabolic rate, your fluid intake, the type of drug used, and the degree of exposure to the drug toxin.
THC (delta-9-tetrahydrocannabinol) is one of nearly 400 chemicals found in a cannabis (marijuana) plant; it is the particular chemical that accounts for most of marijuana's mind-altering (psychoactive) or so-called pleasurable effects. The strength of the drug (marijuana) and the degree of mind-altering effects obtained after smoking the drug is determined by the amount of THC it contains, and this varies from plant to plant.
In order to answer the question "how long does THC stay in the body?", you have to first understand how the drug is absorbed into the body and how it is metabolized by the body. The THC in marijuana enters the bloodstream within minutes of being smoked (within 30 minutes to 2 hours if ingested orally) and is then rapidly absorbed and stored in fatty body tissue, including the brain, liver, bladder, and kidneys. The fact that THC is fat soluble is the reason why THC is able to remain in the body and be detected for a relatively long period of time when compared to other controlled substances. Once it is stored in the fatty tissues of various organs, THC is slowly released and metabolized by the body. The metabolites (byproducts of the drug after it has run its course throughout the body) of THC are then excreted and cleared from the body; these metabolites of THC (specifically 9-carboxy-THC) are detectable for a much longer period of time than THC is, and this is the reason why most drug toxicology tests look for the metablolites of THC rather than the THC itself.
As pointed out earlier, marijuana's effects on the body and the speed at which it leaves the body (the detection time) is dependent on many variables, but especially on the strength or potency of the marijuana (the amount of THC contained in the plant). It has been estimated that marijuana can have a half-life (the amount of time that it takes for half of the total amount of drug taken to be eliminated from the body) ranging from 1-15 days; therefore it can be expected that the drug will remain detectable in the body for 2-30 days. Since marijuana is an illegal drug, not a pharmaceutical product regulated by the FDA, it is impossible to predict the potency of the drug or what the half life of a particular plant will be. The detection time is also influenced by the amount of exposure you have to the drug. If you inhale second-hand marijuana smoke, there may be detectable metabolites in your body for several days. If you smoke it occasionally, it will usually remain in your system for up to 10 days. If you smoke it on a regular basis it will stay in your system for up to 45 days. THC has a cumulative effect, so if you smoke marijuana heavily on a daily basis, it can stay in the body for up to 90 days. This is because THC is stored in the fat cells in the body's major organs, including the brain, the liver, the bladder, and the kidneys. Once the THC is stored, it is slowly broken down to it's active metabolites (the detectable traces of THC), which can be picked up on a drug test.
Drug tests can detect active drugs as well as their metabolites. Drug testing can be done by analyzing blood, urine, hair follicles, and even saliva. As can be seen from the preceding information, the answer to the original question of "How long does THC stay in the body?" is extremely complicated, as there is not a simple formula or calculation for a time limit between when the drug is ingested and when it will no longer be detectable. There is much human variation as well as variation between different types and species of cannabis plants. To complicate matters even more, there are tests that look for a much smaller cut-off amount of the drug; some tests detect up to 50ng/ml, whereas other tests are more sensitive and will detect a smaller, trace amount.
There are numerous websites that offer home cleansing remedies that claim to rid the metabolites of THC from your body, and others that offer home testing kits. None of these, however, have been proven to be effective; in fact the general opinion is that these sites are a huge scam. Increasing your metabolism through vigorous physical exercise may theoretically remove traces of drugs from your body. Others say that flushing your system with a lot of extra water will increase the elimination of THC. This all sounds ridiculous, if you consider that the THC is bound to the fat cells in the body. Water is not going to flush the THC out of the fat; it's only usefulness may be to help the kidneys to eliminate the metabolites of the THC through the urine.
The best way to be sure to pass a drug test is to not use drugs. The purpose of this article is not to discuss or debate the dangers of drug use, however I feel that I would be remiss if I did not mention that marijuana, although deemed to be harmless by many, is an illegal drug and its use has consequences in our society. Regardless of how much one may feel that it should be legalized, the fact of the matter is that it is not. I will even go so far as to support the argument that other things (such as cigarettes) are equally as harmful and should also be illegal, however that is not the way things are, and as members of a civilized society we need to live by the laws. We don't get to pick and choose which ones to obey because we agree with them. In addition to the legalities, consider once again that THC contains over 400 chemicals, many of which have proven to be carcinogenic. In most cases marijuana is smoked, which causes damage to the lungs such as chronic bronchitis, emphysema, and lung cancer. THC is stored in the fat in various organs; it has been shown to contribute to bladder cancer, just as cigarettes are. In an era where society's focus is on health and wellness, where we are concerned about e-coli poisoning in our food and about vaccinations for infectious diseases, it just makes no sense to inhale over 400 toxic chemicals directly into the lungs, does it?