How Long Do Different Drugs Stay in Your Sys​t​e​m?

By May Wilkerson 02/23/16

Other factors like your metabolism and the amount of drugs you take also affect the results of a drug test. 

How Long Do Different Drugs Stay in Your Sys​t​e​m?
Photo via Business Insider

If you’ve ever had to take a drug test on the tail end of a bender, you may have wondered how long illicit drugs stay in your system. The short answer is: it depends on the drug, the amount you ingest and the type of drug test.

How do drug tests work?

After you snort, swallow, inject or smoke a drug, your body begins to break it down the moment it enters your body. As the drug is broken down, metabolites (or byproducts) of the drug remain in your blood, urine and/or your hair, for hours or even days or weeks after the effects of the drug subsides.

Drug tests work by picking up traces of these lingering metabolites, which indicate that a person has actually ingested the drug, instead of just coming into contact with it. Interestingly, hair-based drug tests tend to be the most accurate, while tests of blood and urine are usually only able to detect most drugs within a week after you’ve used them. Marijuana is detectable for the longest time by any kind of drug test. But different drugs remain detectable for varying amounts of time, depending on both the drug and the method of testing.

Graphic courtesy of Business Insider/Dragan Radovanovic

Metabolites remain in the blood for the least amount of time, compared to hair or urine. Traces of drugs like alcohol, LSD, morphine, heroin, amphetamines, and alcohol all remain in the blood for just 12 hours or less. Meth, MDMA, cocaine and barbiturates remain in the blood between 37 and 48 hours. Marijuana can be detected for much longer, up to 336 hours or about two weeks.

Urine tests are able to detect drugs for a slightly longer time on average, about three days for amphetamines (like speed) and LSD, about four days for MDMA, cocaine, barbiturates and heroin, five days for alcohol, six days for meth, and up to 30 days for marijuana. 


Graphic courtesy of Business Insider/Dragan Radovanovic

Hair-based tests are the most accurate, since traces of most drugs, everything from alcohol to heroin to cocaine to meth, can remain in your hair follicles for up to 90 days. LSD is the drug that is most difficult to detect with this kind of test, since it is no longer detectable in hair follicles after only about three days.

So if you’re planning on partying hard prior to an upcoming drug test, you have some math to do.

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May Wilkerson is a writer, comic and Managing Editor @someecards. Co-host of the podcast Crazy; In Bed w/alyssalimp. She is also the top Google result for "insufferable lunatic." Follow this insufferable lunatic on Twitter.