How Long Does THC Stay in Your system?

Liz Filmer
20 Oct 2022

Weed is usually detectable in bodily fluids up to 30 days after use. As with other drugs, it may be noticeable for several months in hair, particularly in those who use cannabis regularly.

Drug Testing

Drug testing measures levels of THC and its metabolites (by-products). Metabolites will remain in your system long after the initial effects have worn off. 

How long cannabis is detectable depends on how much you smoke or ingest and what drug test is used. 

While detection windows may vary, weed can be detected in urine for a varied amount of time, depending on the amount of use:

  • single use: 3 days
  • moderate use: 5 to 7 days
  • chronic use: 10 to 15 days
  • regular heavy use: over 30 days

Cannabis metabolites are fat-soluble and bind to fat molecules in your body. Therefore, it can take a long time for them to leave your system, especially if you have more fat molecules in your body. 

Saliva Testing

THC may be more present in oral fluid longer than in blood after acute use. Saliva testing has a short detection window. A 2020 study discovered that THC could still be detected in the saliva of regular smokers 72 hours after use. 

Weed enters the saliva via smoking or smoke exposure. Metabolites are only present in saliva when the weed has been smoked or ingested. In jurisdictions where weed is illegal, they may use oral fluid to test drivers.

Hair Testing

Hair follicle tests can identify drug use for up to 90 days. Cannabinoids reach the hair follicles via tiny blood vessels surrounding the hair shaft. Hair grows on average 0.5 inches per month, so a 1.5-inch hair segment close to the scalp will provide a test result for the three months prior.

How long does it take to break down?

THC is absorbed by the bloodstream and broken down in the liver. It has more than 100 metabolites which stay in your body longer than THC. How long before THC metabolites are entirely excreted from the body depends on the frequency of cannabis use. The more THC metabolites in your body, the longer it takes for them to pass. 

Your body mass index (BMI) and metabolic rate aren’t linked to weed. Still, they are related to how the body processes and metabolises cannabis. Other factors include how you use it, dose, frequency, route of administration, and potency.

More potent weed may also stay in your system for longer, as will weed you have eaten in edibles.

How can you metabolise it faster?

Once THC is in your system, your body needs to break it down. Exercising, eating healthy, and staying hydrated will all help but not drastically. You can buy weed detox remedies and kits online. Many require drinking a lot of water to dilute urine and using herbal supplements such as creatinine or vitamin B12 to mask the dilution. Be warned, however, that these kits don’t work reliably, and drinking large quantities of water in a short period can be dangerous. 


Liz Filmer