Most drugs clear from urine within 1 to 4 days, but cannabis is the major exception, staying detectable for up to 30 days in daily users and potentially even longer in chronic heavy users. The exact window depends on the substance, how often you use it, your metabolism, and the sensitivity of the test. Below is a comprehensive breakdown of detection times for every major drug category, along with the factors that shift those numbers in real life.
Urine Detection Times by Drug
These windows reflect standard immunoassay screening tests, the type used in most workplace, legal, and clinical settings. Times are measured from last use.
- Marijuana (THC): 1 to 3 days for a single or occasional use. 5 to 10 days for daily use. Up to 30 days for chronic heavy use.
- Cocaine (including crack): 2 to 3 days
- Amphetamine and methamphetamine: 2 to 4 days
- MDMA (ecstasy/molly): 2 to 4 days
- Heroin: 1 to 2 days
- Codeine and morphine: 1 to 3 days
- Oxycodone: 1 to 1.5 days
- Hydrocodone: Up to 2 days
- Fentanyl: 1 to 2 days
- Benzodiazepines (short-acting, like alprazolam): 1 to 5 days
- Benzodiazepines (long-acting, like diazepam): 1 day to 6 weeks, depending on dose and duration of use
- PCP (phencyclidine): 3 to 7 days for casual use, up to several weeks for chronic use
- Alcohol (standard test): 12 to 24 hours
- Alcohol (EtG metabolite test): Up to 48 hours after a few drinks, 72 hours or longer after heavy drinking
- Buprenorphine: 3 to 4 days (requires a specific test, won’t show up on a standard opiate screen)
Why Cannabis Has the Longest Window
THC is fat-soluble, meaning your body stores its byproducts in fatty tissue and releases them slowly over time. For someone who smokes once, those byproducts peak in urine about 10 to 18 hours later and typically fall below detectable levels within 80 to 100 hours, roughly 3 to 4 days.
Chronic daily users are in a completely different situation. Research from the National Institute on Drug Abuse found that after sustained daily use, THC byproducts can remain detectable for up to 30 days with lab-grade testing. In some cases with particularly heavy, long-term use, positive results have been recorded at 67 and even 93 days after the last use. No other commonly tested drug comes close to this kind of accumulation.
Synthetic Opioids Need Separate Tests
A standard urine drug screen tests for natural opiates like morphine and codeine. Many synthetic and semi-synthetic opioids simply don’t trigger that screen. Fentanyl, oxycodone, hydromorphone, and buprenorphine can all produce a negative result on a basic opiate immunoassay, even if you used them recently. Detecting these substances requires a test specifically designed for each one.
This matters in two directions. If you’re prescribed oxycodone and take a standard drug test, it may not show up at all. And if someone is being monitored for fentanyl use, a basic panel won’t catch it. Federal workplace testing panels now include fentanyl as a separate line item with its own cutoff level, but not all employers or clinics use the expanded panel.
What Federal Workplace Tests Actually Screen For
The federal standard, used by all Department of Transportation employers and many private companies, tests for marijuana, cocaine, amphetamines (including methamphetamine and MDMA), opioids (codeine, morphine, heroin, hydrocodone, hydromorphone, oxycodone, oxymorphone), fentanyl, and PCP. That’s it. Benzodiazepines, barbiturates, and other substances aren’t part of the federal panel, though private employers can add them.
Each substance has a specific threshold that must be exceeded before the test counts as positive. Marijuana, for example, uses an initial screening cutoff of 50 ng/mL. If the screen is positive, a confirmation test checks for the specific THC metabolite at a lower threshold of 15 ng/mL. Cocaine’s initial cutoff is 150 ng/mL, amphetamines sit at 500 ng/mL, and fentanyl has a very low threshold of just 1 ng/mL, reflecting how potent it is in small amounts. These thresholds mean that trace exposure or very low levels may not produce a positive result.
As of June 2023, the DOT also authorizes oral fluid (saliva) testing as an alternative to urine. Employers can choose one or the other for any testing event but cannot require both. Oral fluid tests generally detect more recent use, with shorter detection windows than urine for most substances.
Factors That Change Your Detection Window
The ranges listed above are averages. Several things push your personal window shorter or longer.
Frequency and duration of use is the biggest factor. A single dose of any substance clears faster than repeated doses, because repeated use allows the drug or its byproducts to accumulate in your body. This effect is most dramatic with cannabis and long-acting benzodiazepines, where casual and chronic use can differ by weeks.
Body composition plays a role for fat-soluble substances like THC. People with higher body fat percentages tend to store more THC byproducts and release them more slowly. Hydration level affects how concentrated your urine is at the time of the test, which can push borderline results one way or the other, though labs check for overly diluted samples. Metabolism, age, liver function, and kidney function also influence how quickly your body processes and eliminates a substance.
False Positives From Common Medications
Standard urine screens use immunoassay technology, which works by detecting the shape of drug molecules. The problem is that some legal, everyday medications have molecular shapes similar enough to trigger a positive result for a drug you never took.
Dextromethorphan, the active ingredient in most “DM” cough suppressants, can cause a false positive for PCP. So can diphenhydramine, the antihistamine in Benadryl. Tramadol, a prescription pain reliever, has been linked to false positives for both PCP and opiates. Research published in Clinical Toxicology found that tramadol, dextromethorphan, and even some benzodiazepines like alprazolam and clonazepam were significantly associated with false positive PCP results.
If you test positive on an initial screen, a confirmation test using more precise technology can distinguish a true positive from a false one. This second test is standard practice in federal workplace testing and most clinical settings, so a false positive from cough medicine shouldn’t lead to a final positive result as long as the confirmation step happens.