How Long Do Drugs Stay In A Body's System?

Admit it: you raved all night at Burning Man, and the whole experience was otherworldly. But now you're heading back to work wondering how long your week of fun will remain in your system. It's important to plan ahead for these kinds of things, particularly since failing a test for substances can mean the difference between everything from keeping a job to maintaining a place on your sports team to saving a life. There is no clearcut timeline of drugs making their way through a person's liver and kidneys before being flushed out of the body via sweat, urine, or defecation: the best idea for passing a test is to avoid certain substances in the first place. 

But if you've gone ahead and partied already, you will want to know how your body processes them. The way your body works through hard substances depends on the type of drug, the level of use, the health of the kidneys and liver of the user, and one's fitness level. The type of test being administered and what bodily fluids are used for detection determines the timeframe for testing positive for use. The worst drugs for you to ingest can be found in blood, urine, saliva, and even hair for days or weeks after use. But each drug is different, and looking at the whys and hows is fascinating - and may lead to more caution in the future.


  • Cannabis is most commonly smoked, though some people ingest it via oils or by integrating it into baked goods and teas. The drug enters the bloodstream through the lungs or digestive system, spreading cannabinoids including THC into the brain and other organs in the body. The result is that euphoric, relaxed feeling AKA "a high." Cannabis metabolizes via water, thus moving through and leaving the body fairly quickly through urine; the process takes longer if you take an edible versus if you smoke it.

    Delta-9 THC, on the other hand, is a psychoactive variation which gets caught on your saliva glands inside your mouth. It doesn't really enter the bloodstream - it's chemical makeup doesn't allow for that - and so it stays in your mouth until you take care of it. Eating fatty foods which act as magnets for THC or brushing your teeth can help expedite the process.

    Cannabis can be detected in urine for several days after use, and sometimes even 30 days after use. You're probably safe to take a blood test after two weeks, but it can hang around in your hair follicles for as long as 90 days - longer than in any other part of your body. The weirdest part is that you can also test for cannabis use from years previous - that's how long the traces remain. Certain detox cleanses can help flush your system with a tight turnaround, though, but traces of regular use are harder to eliminate than more sporadic usage.

  • Heroin
    Photo: Unknown / Max Pixel / Public Domain

    Heroin (H) can be smoked, snorted, inserted as a suppository, ingested, or injected. Injection is the quickest way to get the drug into the bloodstream, with a suppository being the next fastest route. Users experience euphoria, become less anxious, and feel warmer. H is highly habit-forming, and the effects are typically longer-lasting than other drugs including cocaine and methamphetamines. However, according to American Addiction Centers, a nonprofit organization for recovering addicts:

    [H] has a particularly short half-life of only 30 minutes. This means that if a user takes a single dose [...] it will take 30 minutes for half of the drug in the person’s system to be flushed out. Some studies suggest that this half-life is as short as 3 to 8 minutes.

    After the high, the body begins to metabolize the substance and its effects dissipate within hours. Tests can detect H in the bloodstream for about 12 hours, in saliva for 24 to 48 hours, two to seven days via urinalysis, and up to three months in hair follicles. 

  • LSD
    Photo: Psychonaught / Wikimedia Commons / Public Domain

    Lysergic acid diethylamide is commonly known as acid. It is a hallucinogen synthesized from a fungus that is usually ingested in a pill form or by placing paper that has been soaked in the substance into the mouth. Once ingested, the user will feel the effects within 30 to 45 minutes; a "trip" consists of delusions, hallucinations, mood swings, and impaired perception. 

    Blood can be tested for up to five hours after ingestion and still detect the drug. Urine and hair tested within three days of ingestion may also test positive. 

  • Cocaine (coke) is a stimulant that is commonly snorted, though it may also be dissolved in water and injected directly into the bloodstream. Crack combines powdered coke with water and sodium bicarbonate - typically baking soda - and may be smoked. 

    Snorting the drug allows it to enter the bloodstream via mucous membranes in the nose and give the user a boost of energy for up to half an hour. Injecting or inhaling the substance brings on the high more quickly, but it doesn't last as long - the average high lasts 10 minutes.

    After using coke, it can be detected in a blood test for up to two days; in urine for as many as 4 days; and in hair follicles for nearly three months. 

  • This psychoactive drug is also known as Molly or E when cut with other drugs such as coke, ketamine, methamphetamines, or others. In 2009, it was reported that "most ecstasy pills contained less than three percent MDMA, if any at all." However, when a new chemical was developed in China, manufacturers of MDMA jumped, resulting in higher dosages in the average pill. 

    In most forms, MDMA or E provides a stimulant effect triggering the release of serotonin in the user's brain. Ecstasy can be ingested in pill or liquid form and can be snorted. Users have lowered inhibitions, become more impulsive, and experience heightened emotional senses with elevated empathy for others. It gained popularity in nightclubs and with ravers, but is also now seen outside that realm.

    This substance can be detected in a user's blood for up to two days in blood, up to four days in urine, and up to 90 days in hair follicles.

  • Methamphetamine
    Photo: Psychonaught / Wikimedia Commons / Public Domain

    Methamphetamine can be snorted, smoked, injected, or ingested via mouth to achieve stimulation that can lead to binges of obsessive behaviors and inability to sleep. It has long-reaching consequences on a user's health the longer they indulge, but the window for detecting it in tests is smaller by comparison.

    After using the substance, blood testing will reveal it for up to three days. A urine test can deliver a positive result for up to six days and it can be detected in hair for nearly three months. As with many of these highly habit-forming drugs, however, it is rare that a user uses once, and the residual effects are much more deep-seated and long-lasting.