The main ingredient of Marijuana, THC (TetraHydraCannabinol), has a half-life of about 10 days. The metabolic rate of the individual user will be the determining factor as to how long the THC will be detected in the urine. Users with fast metabolic rates and low usage will have the shortest detection times, while chronic use of Marijuana combined with slow metabolic rates will extend detection times. Fluid intake before the tests will also have a determining factor, high amounts of liquids such as water (in multiple liters) will likely flush the system fairly fast for infrequent users. The smartest thing is to allow maximum time needed for THC to be out of the system; thus, estimates of up to 60 days are best and will keep the user on the safe side during drug tests. In general, Marijuana detection depends on many factors such as frequency, dosage, and last time of use, genetic makeup of the individual, digestive and excretory systems, and the state of an individual’s metabolism.
Marijuana Detection Time Based on Usage
|Usage||Days of Detection|
|1 time only||5-8 days|
|2-4 times /month||11-18 days|
|2-4 times /week||23-35 days|
|5-6 times /week||33-48 days|
|Daily Usage||49-63 days|
The most common drug test for marijuana is the urine test that can detect the drug for days or weeks after use. It is worthwhile to note that urine tests do not detect THC (delta-9-tetrahydrocannabinol), the psychoactive component in marijuana, and therefore in no way can measure impairment. Urine tests can only detect THC-COOH, the non-psychoactive marijuana metabolite, which can linger in the human body for days and weeks with no impairing effects. Moreover, urine tests are more sensitive to marijuana than other commonly used drugs due to THC-COOH’s unusually long elimination time.
Blood tests have proved to be improved detectors of marijuana use as they measure the actual presence of THC in the body. However, they are used less frequently as urine tests as they are invasive and difficult to administer.
Considered to be the most objectionable form of drug testing, hair tests do not measure current marijuana use, but rather non-psychoactive residues absorbed internally and do not appear in the hair until 7-10 days after first use (the residues remain in the hair for months afterwards). These residues cannot be cleaned by shampoos, though some shampoos are better than others for cleaning such residues. Hair testing is effective in detecting regular than occasional marijuana use. It is worthwhile to note that such tests are sensitive to one-time use of marijuana.
Saliva testing is a new technology that is yet to prove its worth. Sensitivity of such tests is not clearly and well established in the context of marijuana. In theory, saliva testing for marijuana is supposed to detect marijuana use of recent times, but this could range from several hours to over a day. Saliva marijuana tests are supposed to detect secretions from inside the oral tissues, which cannot be washed out with mouthwash.