Weed detection windows depend on how much you smoke or ingest, as well as how often. In general, higher doses and more frequent use are associated with longer detection times.
For daily users, cannabis may be detectable for several months after last use. The longest-reported detection times are more than 90 days.
How long is it detectable via drug testing?
Drug tests measure weed and its by-products, or metabolites. These metabolites remain in your system long after weed’s effects have worn off.
According to Mayo Clinic Proceedings, weed is detectable in urine for the following amounts of time after last use:
- Occasional users (up to three times a week): 3 days
- Moderate users (four times a week): 5 to 7 days
- Chronic users (daily): 10 to 15 days
- Chronic heavy users (multiple times a day): more than 30 days
Cannabis metabolites are fat-soluble, which means they bind to fat molecules in your body. As a result, it can take some time for them to leave your system.
Urine testing is the most common testing methodTrusted Source.
According to an article in Therapeutic Drug Monitoring, weed is typically detectable in the blood for 1 to 2 days. However, in some cases, it’s been detected after 25 days. Chronic heavy use increases the length of time that it can be detected.
Weed is detectable in the bloodstream within seconds of inhalation. It’s distributed to the tissues. Some of it is reabsorbed in the blood and broken down. Its metabolites may remain in the bloodstream for days.
Blood testing may be used in laboratory settings or to indicate recent use of weed.
According to a 2014 reviewTrusted Source on cannabinoids in oral fluid, weed is detectable in saliva for the following amounts of time after last use:
- Occasional users: 1 to 3 days
- Chronic users: 1 to 29 days
Weed can enter the saliva through smoking and exposure to smoke. However, its metabolites are only present in saliva when weed has been smoked or ingested.
In jurisdictions where weed is legal, oral fluid may be used for roadside testing.
Hair follicle tests assess drug use for up to 90 daysTrusted Source. After use, weed reaches the hair follicles via small blood vessels. Trace amounts may remain in the hair.
Since hair grows approximately 0.5 inches per month, a 1.5-inch hair segment taken close to the scalp can provide a window of weed use for the past three months.
How long does it take to break down?
The active ingredient in weed is a chemical substance called THC, which stands for delta-9-tetrahydrocannabinol. THC that enters your body is absorbed into the bloodstream.
Some THC is temporarily stored in organs and fatty tissues. In the kidneys, THC can be reabsorbed into the bloodstream.
THC is broken down in the liver. It has more than 80 metabolites, but the most significant ones are 11-OH-THC (11-hydroxy-delta-9-tetrahydrocannabinol) and THCCOOH (11-nor-9-carboxy-delta-9-tetrahydrocannabinol).
Drug tests look for these metabolites, which stay in your body longer than THC. Eventually, THC and its metabolites are excreted in urine and stool.
What factors affect how long it stays in your system?
A number of factors affect how long weed stays in your system. Some of these factors, such as your age, gender, and body mass index (BMI), aren’t related to the drug itself, but to how your body processes and metabolizes the drug.
Other factors are related to weed and how you use it. This includes how much you take (dose) and how often (frequency). Higher doses and more frequent use tend to increase the amount of time it takes to eliminate weed from your system.
More potent weed, which is higher in THC, may also stay in your system for longer. Weed that’s ingested may also remain in your system slightly longer than weed that’s smoked.
Mouth Swab Testing For Common Drugs
Due to the ease of testing, mouth swabs are becoming far more common in drug testing. In a mouth swab, a standard cotton swab is rubbed on the inside of the cheek to collect biological material. These swabs are then processed in a lab for everything from genetic information to foreign substances in the saliva.
As with blood and urine testing, the appearance of drugs within the body is detectable on varying timelines depending on the substance in question. Like other testing alternatives, oral swabs largely look for metabolites of drugs; these are the chemicals left behind after the body has processed a particular substance.
Mouth swabs are generally screened using enzyme immunoassay technology. Any samples that test positive will the be tested again using more specific methods, which may include liquid chromatography, mass spectrometry, and mass spectrometry to confirm findings.
More colloquially known as meth, methamphetamine is a stimulant that causes euphoric effects and can be smoked, snorted, and ingested. Meth isn’t a natural substance; it is created in a makeshift lab using ingredients like acetone, hydrochloric acid, ammonia, and ephedrine. It lasts longer in the body than some similar drugs, like cocaine, with its byproducts peaking around 12 hours after use.
Using an oral swab, meth can be detected as soon as 10 minutes after use and is identifiable for up to four days later for heavy users. Meth’s detection window is generally longer using other testing forms, like blood or urine tests.
Marijuana, a drug derived from a plant that is now legal in several states, offers euphoric effects when smoked or ingested through alternate methods. Its life in the body is far longer than most standard substances, particularly for regular users, as THC metabolites are stored in fat cells and slowly released into the bloodstream. For the average person, fat cells tend to linger, leading to detection windows as long as six weeks via its metabolites via blood or urine testing.
Unlike urine tests, which tend to look for the metabolite THC-COOH, oral swab tests search for THC itself as this substance remains in the saliva before being metabolized within the body. Saliva tests can identify marijuana use within the last 24 hours, making it a leading choice for police officers and others looking for the confirmation of recent use.