Different types of drugs stay in the body for different lengths of time after last use, depending on several factors, and the detection window for identifying drug use varies, depending on these factors and the drug testing method, such as urinalysis, oral fluid, or hair, that is used to collect a specimen.
Certain drugs, like marijuana, will remain in a users system significantly longer if they are used more frequently, because they are stored in the body, rather than being quickly excreted as they would in an occasional user. Other drugs, like cocaine, tend not to build up in a users body regardless of how frequently they are used. Most drugs will remain identifiable in a urine sample for significantly longer than they will in saliva sample, while a hair sample will provide the longest detection window, regardless of the drug in question.
Some of the factors that may affect how long drugs stay in someone’s system include:
- Type of drug
- Frequency of use
- Weight, height, and gender
Drug testing methods
Urinalysis drug test
Urinalysis is the industry standard, and currently, the only method approved for DOT drug testing. This method is fast, easy, and inexpensive, but it does have some drawbacks. You need to secure a private restroom, disable the sink and toilet, and place a bluing agent into the water in the toilet bowl. Privacy concerns may also be an issue because a test must be conducted by an administrator of the same sex.
This method has a long detection window but cannot detect drug use that has occurred within the last few hours.
Oral fluid / mouth swab drug test
Mouth swab drug testing is just as accurate as urinalysis. It’s also just as fast, easy, and inexpensive, but by far, its greatest advantage is that it can be conducted literally anywhere—even in plain view of other employees, because it only requires a sterile cotton swab to be rubbed along the inner cheek to collect a small saliva sample.
While this method has the shortest detection window, it can detect drug use almost immediately after use.
Hair drug testing
Hair drug testing offers the same convenience of oral fluid drug testing, and can be conducted anywhere, but it is more expensive than other methods. This test requires the collection specialist to clip a small 1” wide section of hair, preferably near base of the scalp, and secure it in a specially labeled container. While this testing method is easy and convenient, some employees may take issue with having their hair cut.
This method has the longest detection window, but it cannot detect recent drug use.
Drug use detection windows
|Amphetamine-Type Stimulants||LOQ (ng/mL)||Detection Time* up to|
|3,4‑Methylenedioxyamphetamine (MDA)||25||2 days|
|3,4‑Methylenedioxymethamphetamine (MDMA)||25||2 days|
Note: These tests do not differentiate between dextro (+) amphetamines (eg, dexamphetamine) and racemic mixtures of dextro (+) and levo (-) isomers that are present in “street” amphetamines. These tests do not differentiate between ephedrine and pseudoephedrine.
|Barbiturates||LOQ (ng/mL)||Detection Time* up to|
|Benzodiazepines||LOQ (ng/mL)||Detection Time* up to|
|Diazepam as metabolites||100|
|Alprazolam as metabolite||100|
|Chlordiazepoxide as metabolite||100|
|Clonazepam as metabolite||100|
|Flunitrazepam as metabolite||50|
|Triazolam as metabolite||100|
|Flurazepam as metabolite||100|
|Buprenorphine||LOQ (ng/mL)||Detection Time* up to|
|Cocaine & Metabolite||LOQ (ng/mL)||Detection Time* up to|
|Fentanyl||LOQ (ng/mL)||Detection Time* up to|
|Ketamine||LOQ (ng/mL)||Detection Time* up to|
|Lysergic Acid Diethylamide (LSD)||LOQ (ng/mL)||Detection Time* up to|
|Marijuana/Cannabis (THC-COOH)||LOQ (ng/mL)||Detection Time* up to|
|Single Use||3||3 days|
|Moderate Use (4 times per week)||5 days|
|Heavy Use (daily)||10 days|
|Chronic Heavy Use||30 days|
|Methadone||LOQ (ng/mL)||Detection Time* up to|
|EDDP (methadone metabolite)||100||7 days|
|Opiates||LOQ (ng/mL)||Detection Time* up to|
|Phencyclidine||LOQ (ng/mL)||Detection Time* up to|
*These are approximate detection times for the drug or metabolites in urine. The actual detection time depends on dose, frequency of use, and individual metabolism.