How Long Do Drugs Stay in Your System? Urine, Saliva, Blood and Hair Detection Times

SAMHSA’s clinical drug testing guide says most drugs can be found in urine for about 2 to 4 days, and longer after large, frequent doses. Saliva usually covers the last day or two, blood a shorter stretch than urine, and head hair about the last 3 months. Those are starting points. The drug, how much and how often it was used, the person’s body and the test itself all move the number.

Drug detection times by substance

Typical windows after the last use. A linked name goes to the page that covers that drug in depth.

Sources: SAMHSA’s TAP 32, the ASAM drug testing consensus and the federal MRO manual, plus studies on heavy cocaine use, regular fentanyl use, daily cannabis use, EtG, PEth, and fentanyl and xylazine. “Not well studied” means we found no number we trust, so we print none. SAMHSA calls its own detection-time estimates very broad, because they depend on the substance and how much and how often it was taken.

How long a drug lasts vs how long it shows on a test

Why does a drug that wore off hours ago still show up days later? Because most urine tests are not looking for the drug. They look for what the body turns it into. SAMHSA says that, as a general rule, these metabolites stay in the body longer than the drug itself.

Cocaine is the clearest case. Its half-life, the time for the blood level to fall by half, is about 1 to 1.7 hours according to the FDA label for medical cocaine, which also measured 5 to 8 hours at very low levels with a highly sensitive test. Urine tests look instead for benzoylecgonine, which usually shows for 2 to 3 days after a single use. The drug is half of the answer. The other half is the test. A feeling that has passed tells you nothing about what a sample still holds.

Urine vs blood vs saliva vs hair: how each test works

The saliva range is from the federal MRO manual. ASAM says hair takes about 8 days to grow above the scalp, and SAMHSA says hair suits frequent, heavy use better than occasional use.

What a drug test can and cannot tell you

A positive result says a drug or its metabolite was in that sample above the test’s cutoff. ASAM says that in most cases a drug test does not measure impairment. Since urine mostly carries metabolites, a positive urine test points to use some time before the sample, not to how the person was doing when it was taken. Hair says even less about the present: ASAM says it does not detect recent use or impairment. New Jersey’s cannabis law draws the same line for employers (see below). A negative result is not proof of no use, and ASAM says every test has some rate of false positives and false negatives.

What a standard drug test checks for, and what it misses

There is no single standard test. Federal workplace programs use a fixed panel; clinics, courts and private employers choose their own. So check what the specific panel includes, and at which cutoffs. SAMHSA says federal workplace cutoffs are not appropriate for clinical use.

The federal workplace panel

The HHS federal panel, in effect since July 7, 2025 and unchanged in March 2026, tests urine for marijuana and cocaine metabolites; codeine, morphine and heroin’s 6-AM; hydrocodone, hydromorphone, oxycodone and oxymorphone; fentanyl and norfentanyl; amphetamine and methamphetamine; MDMA and MDA; and PCP. Oral fluid has its own federal panel, which also includes fentanyl. Department of Transportation tests follow a separate rule, 49 CFR Part 40, and as of October 2026 its panel still did not include fentanyl. DOT proposed adding fentanyl in September 2025.

What opiate screens miss

An “opiate” screen is built to catch morphine and codeine. ASAM says methadone, buprenorphine and fentanyl will not be detected in a standard opiate immunoassay and need their own tests, and that oxycodone is caught by a few but not most of them. SAMHSA says the same of synthetic opioids. Neither buprenorphine nor methadone is on the federal panel. A clean opiate screen does not mean no fentanyl.

Benzodiazepines, alcohol, kratom and xylazine

• Benzodiazepines are not on the federal panel. ASAM says most general benzodiazepine screens have very low sensitivity to clonazepam (Klonopin) and lorazepam (Ativan), so a person taking either can test negative.
• Alcohol is not on the federal drug panel; it is tested separately.
• Kratom needs its own test. Labs such as ARUP offer a mitragynine screen with confirmation. Mitragynine’s half-life in regular users was about 23 hours in one study.
• Xylazine, the animal sedative found in the fentanyl supply, is not detected by routine toxicology screens, according to the FDA.

What changes the detection window

SAMHSA lists the factors: how often the drug is used, how much, how fast the body breaks it down, the cutoff of the test, the person’s physical condition and, for many drugs, body fat. It adds that some liver, kidney, hormone and other conditions can extend the window.

• Frequency and dose. Daily or heavy use stretches the window for many drugs in the table, most of all for cannabis.
• The drug and its form. Controlled-release oxycodone shows longer than immediate-release, and diazepam’s metabolite outlasts diazepam itself.
• Urine pH. The Adderall label says amphetamine excretion depends heavily on urine pH, and the MRO manual agrees.
• The cutoff. In a controlled methamphetamine study, lower cutoffs detected the drug earlier and for longer.

These are facts about a body and a test, not levers. Labs check urine samples for validity, and under federal and DOT rules a sample the medical review officer verifies as adulterated or substituted counts as a refusal to test.

False positives and confirmation testing

The first test is usually an immunoassay, a fast screen that reacts to a family of look-alike chemicals. A positive screen is a reason to confirm, not a final answer. The confirmation uses a different method, gas or liquid chromatography with mass spectrometry (GC-MS or LC-MS), which identifies the exact substance, according to the MRO manual.

• Amphetamine screens are especially prone to cross-reactions; SAMHSA calls them extremely cross-reactive and lists decongestants, diet drugs and several prescription medicines. The Wellbutrin XL label warns that bupropion can cause false-positive amphetamine screens, even after stopping it. In a lab study of 100 urine samples that screened positive for amphetamine or ecstasy but failed confirmation, bupropion and trazodone were among the drugs most often present.
• Methamphetamine has legal forms: a prescription tablet (Desoxyn) and the levmetamfetamine in some over-the-counter nasal decongestant inhalers. A chiral test can tell the inhaler form from the form sold illegally. Our meth detection guide explains it.
• Cocaine screens rarely give false positives; SAMHSA says confirmation usually exceeds 99 percent. Lidocaine and benzocaine do not cause a positive. Coca-leaf tea does, and federal rules do not accept it as an explanation.
• Opiates. Large amounts of poppy seeds can cause a positive for morphine or codeine, SAMHSA says.
• Cannabis. SAMHSA says hemp foods are usually too low in THC to cause a positive. Prescription THC (dronabinol, sold as Marinol) does cause one.
• Alcohol markers. ASAM says that, rarely, ethanol-containing products such as hand sanitizer can cause a positive EtG or EtS test.

A prescription and a positive test: how MRO review works

In federal workplace testing, a confirmed positive goes to a medical review officer, a doctor who reviews it before the result is reported to the employer. Under the HHS guidelines, the MRO must contact the person to ask whether there is a legitimate medical explanation, and if the person documents one, such as a valid prescription, the MRO reports the test as negative. DOT rules in 49 CFR 40.137 say the same and tell the MRO not to question whether the prescriber should have prescribed the drug. The burden of proof is on the employee, and the MRO may still raise a safety concern with the employer.

• The MRO manual says useful proof includes the labeled prescription container, or its label, and a copy of the medical record.
• Someone else’s prescription never counts.
• Under federal and DOT rules, a medical marijuana recommendation, hemp products and coca tea are not legitimate explanations, and no explanation is accepted for heroin’s 6-AM, PCP, MDMA or MDA.
• Adderall and Vyvanse produce a positive for amphetamine only, never methamphetamine, the MRO manual says. Our Adderall detection guide covers what that means for a prescription.

Outside federal and DOT programs, ask the employer, court or clinic who reviews a positive and what proof it accepts. Do not stop a prescribed medication on your own before a test. Keep the prescription details and give them to whoever reviews the result; in federal and DOT testing that is the medical review officer, not the person collecting the sample.

In New Jersey

Drug testing in Recovery Court

The Judiciary’s participant brochure describes frequent random drug and alcohol testing, at probation, in court or at other approved sites. Using, drinking, or altering a test can bring a sanction. The Judiciary says a missed meeting or a positive test does not by itself mean termination; the team can respond with a sanction instead. Under the special probation statute, a positive drug test counts as a violation for a person on medication-assisted treatment only if the positive result is unrelated to that treatment, and refusing a test brings revocation unless the judge orders 30 days to six months in jail instead. Our Recovery Court guide covers the rest.

Cannabis and New Jersey employers

This is a summary of the law, not legal advice. For a specific job or test, talk to a lawyer.

Under N.J.S.A. 24:6I-52, part of New Jersey’s 2021 cannabis law as amended in January 2026, an employer cannot take adverse action against an employee solely because cannabinoid metabolites from lawful use are in their bodily fluid, and cannot refuse to hire or fire someone because they do or do not use cannabis. An employer can still test: on reasonable suspicion of use while working, on observable signs of intoxication, after a work accident, at random, before hiring, or as regular screening. The test must combine a reliable objective method, such as blood, urine or saliva testing, with a physical evaluation of impairment, and the employer may use the results in deciding what to do. Employers can still bar drugs and alcohol at work, and an employer bound by federal contract or funding rules may follow federal law instead.

The state’s Cannabis Regulatory Commission said in September 2022 guidance that a test showing cannabinoid metabolites alone is not enough to support an adverse employment action. That guidance was issued as interim, until the Commission sets standards for its workplace impairment certification.

Withdrawal and detox, by type of drug

Someone counting days until a test after weeks of daily use can be asking a second question underneath: can I stop? If the honest answer is not yet, that is worth noticing. With stimulants, the Adderall label lists what can follow stopping after prolonged use: low mood, depression, fatigue, vivid unpleasant dreams, sleeping too little or too much, more appetite, and slowed movement or agitation. The ASAM/AAAP stimulant guideline warns that suicidal thinking may rise as the drug wears off. Alcohol and benzodiazepine withdrawal can cause seizures; the alcohol and benzodiazepine guides below explain why those two need medical supervision.

• Stimulants: our stimulant detox guide, with Adderall withdrawal and the cocaine comedown.
• Opioids: the opioid detox guide, with fentanyl withdrawal.
• Alcohol: the alcohol detox guide and the alcohol withdrawal timeline.
• Benzodiazepines: the benzodiazepine detox guide.

Not sure it calls for detox? See signs you need detox.

For help independent of us, the state’s IME Addictions Access Center at 1-844-276-2777 screens NJ FamilyCare and uninsured residents and refers them to treatment, and ReachNJ, the state treatment line, is at 1-844-732-2465. Periscope Behavioral Health, which publishes this site, is opening a medical detox in Hammonton, Atlantic County, expected Summer 2027. Until it opens, Periscope Behavioral Health at (888) 313-3583, our publisher’s admissions line, can talk through options in New Jersey and Florida, including facilities Periscope operates. What a plan covers depends on the plan and the facility’s network status.