How long benzos stay in your system depends on which benzodiazepine you take, how much, and how often. In a small 2019 study of single doses, an alprazolam (Xanax) metabolite was detectable in urine for a median of 36 hours, while a diazepam (Valium) metabolite was detectable for a median of about 11 days.
Those differences matter for more than drug tests. A benzo taken hours or days earlier can still be active and can add to the effects of alcohol or opioids. Information about outpatient benzo addiction treatment in South Florida is available if benzodiazepine use has become hard to control.
How Long Do Benzos Stay in Your System?
Benzodiazepines are central nervous system depressants that work by binding to gamma-aminobutyric acid (GABA) receptors in the brain. The Food and Drug Administration notes that benzodiazepines differ in how long they take to start working and how long their effects last [1].
That is why there is no single answer. Short-acting benzos are generally eliminated faster than long-acting ones, but no fixed window applies to everyone. Long-acting drugs and their active metabolites can remain in the body for well over a week.
Benzos are one part of a larger group of drugs that slow the brain and body. Our guide to what are depressant drugs explains how they compare with alcohol and opioids.
What Half-Life Means
An elimination half-life is the time it takes a drug’s concentration in the blood to fall by half during its elimination phase. After four to five half-lives, about 94 to 97 percent of the parent drug has been eliminated, under a simple model without further doses. Active metabolites may last longer, and this calculation does not establish a safe time to drink alcohol or take another sedative.
For alprazolam, the prescribing information reports a mean elimination half-life of about 11.2 hours in healthy adults, with a range of 6.3 to 26.9 hours [2]. Peak levels occur about 1 to 2 hours after a dose.
Active Metabolites
As the body processes a benzodiazepine, the liver breaks it into metabolites, some of which are still active. Alprazolam’s two main active metabolites circulate at low levels and have half-lives similar to the parent drug. The label says their low concentrations and potencies mean they are unlikely to contribute much to alprazolam’s effects.
Diazepam is different. Its metabolites remain in the body much longer, which is why diazepam has one of the longest detection windows among commonly prescribed benzos.
Even after the calming effects fade, leftover benzo can combine with an opioid taken later. Our post on how benzodiazepines differ from opioids explains why that combination is so risky.
Short, Intermediate, and Long-Acting Benzodiazepines
Benzos are often grouped by how long they act. These groupings are approximate, and the exact drug, dose, and person all matter.
Short-Acting Benzodiazepines
Short-acting benzos, such as triazolam (Halcion), work and wear off quickly. They are sometimes prescribed for trouble falling asleep.
Intermediate-Acting Benzodiazepines
Intermediate-acting benzos include alprazolam (Xanax), lorazepam (Ativan), and temazepam (Restoril). They are commonly prescribed to treat anxiety and panic disorders, or insomnia in the case of temazepam.
Long-Acting Benzodiazepines
Long-acting benzos include diazepam (Valium), clonazepam (Klonopin), and chlordiazepoxide (Librium). Some are also used for seizures, muscle spasms, or alcohol withdrawal.
Because they last longer, their effects and detection times extend further. That matters when opioids are also involved, as our post answering are opioids depressants explains.
Benzodiazepine Detection Times by Test Type
Detection times depend on the testing methods used. Urine tests are widely used, but saliva tests, blood tests, and hair testing are also used in some settings.
Urine Tests
A study in the Journal of Analytical Toxicology tested 11 healthy volunteers after single therapeutic doses, using sensitive laboratory methods [3]. The alprazolam metabolite alpha-hydroxyalprazolam was detected in urine for a median of 36 hours, with a range of 26 to 61 hours. The longest-detected diazepam metabolite, oxazepam, had a median detection time of 252 hours, or about 11 days.
These numbers reflect single doses and the study’s testing methods, not a guaranteed window for a routine screen. Repeated use can lead to accumulation and longer detection. A positive urine result shows exposure, not how impaired someone is or when it is safe to combine medicines [4].
Saliva Tests
The same study found shorter windows in oral fluid. Alprazolam was detected for a median of 26 hours, and a diazepam metabolite for a median of about 132 hours, or roughly five and a half days.
Blood Tests and Hair Testing
Blood testing can help clinicians relate current symptoms to drug concentrations. Hair testing can provide evidence of past exposure over a longer period, depending on the length of hair analyzed, but is poorly suited to very recent use. Detection depends on the specimen, drug, and test.
Immunoassay Screening and Confirmatory Testing
Drug testing often starts with an immunoassay screen for a drug class, but some laboratories use definitive testing first. Screening results are presumptive. Unexpected results, or results that will guide important care decisions, should be checked with a definitive method such as mass spectrometry, which can identify specific drugs and metabolites.
Screening tests do not detect benzodiazepines equally well and may miss certain benzos, so results vary by the exact drug and the test used. Two people taking the same benzodiazepine can also test positive for different lengths of time.
What Factors Affect How Long Benzos Stay?
Several factors affect how long benzos stay in your system, because each changes how quickly the body processes a benzo. The alprazolam prescribing information shows how much they can matter:
- Age: mean half-life of 16.3 hours in healthy older adults
- Body composition: 21.8 hours in a group of people with obesity, who tend to have higher body fat percentages
- Liver impairment: 19.7 hours, ranging up to 65.3 hours, in alcoholic liver disease, compared with a typical mean of about 11 hours in healthy adults
- Certain medications: drugs such as ketoconazole, fluvoxamine, and erythromycin raise alprazolam levels
- Smoking: alprazolam levels may be up to 50 percent lower in people who smoke
Dose, how often the drug is taken, and the specific medication also shape how long benzodiazepines stay in your system.
Alcohol affects more than the liver. It is a depressant that adds to a benzo’s effects, even in drinks with an energizing reputation, as our post on the tequila myth explains.
Why Benzodiazepine Detection Times Matter for Safety
A benzo can keep working after you stop feeling it. That matters especially when other depressants are involved, because the effects add together.
Benzodiazepines are controlled substances, and the FDA notes that they are widely prescribed, often for long periods, so many people take them alongside other medicines. Telling every prescriber and pharmacist about all your medications, including over-the-counter sleep aids, helps them spot risky combinations with prescription medications.
The FDA added its strongest warning to opioid and benzodiazepine labels in 2016 because combined use led to slowed or difficult breathing and deaths [5].
The FDA reports that benzodiazepine-involved overdose deaths rose from 1,298 in 2010 to 11,537 in 2017 [1]. Our post on respiratory depression explains how that slowed breathing develops.
Alcohol and Lingering Benzos
The FDA advises against drinking alcohol with benzodiazepines because alcohol raises the risk of serious and life-threatening side effects. A long-acting benzo taken the day before can still be in the body. The FDA’s review also found that benzodiazepine misuse often involves alcohol and opioids, which worsens the risks.
Overdose Warning Signs
The Xanax prescribing information describes benzodiazepine overdose as ranging from drowsiness to coma, with confusion, poor coordination, and slowed reflexes in milder cases. Severe cases can involve respiratory depression, especially when other depressants are involved.
The label adds that markedly abnormal blood pressure, heart rate, or breathing raises concern that other drugs or alcohol are involved. Our post asking do opioids lower blood pressure explains one reason why. Call 911 for anyone who is hard to wake or breathing slowly.
Do Not Stop Suddenly
Benzodiazepine dependence can develop quickly. The FDA warns that physical dependence can occur when benzos are taken steadily for several days to weeks, even as prescribed, and that stopping abruptly can cause withdrawal symptoms, including seizures, which can be life-threatening.
Waiting for a benzo to leave your system is not a reason to stop it on your own. A prescriber can plan a gradual reduction under medical supervision to limit withdrawal symptoms.
Frequently Asked Questions About Benzos and Detection
How Long Does It Take for Benzos to Wear Off?
The noticeable effects of many benzos wear off within hours, but the drug can stay in your system much longer. Alprazolam’s mean half-life is about 11 hours in healthy adults, while long-acting benzos such as diazepam last far longer. Lingering amounts can still add to the effects of alcohol or opioids.
What Is the Longest-Lasting Benzo?
Diazepam (Valium) is among the longest-lasting benzos, along with chlordiazepoxide (Librium) and clonazepam (Klonopin). In one study, a metabolite of a single diazepam dose was detected in urine for about 11 days. Because effects can last into the next day, combining these with other depressants is especially risky.
Why Am I Still Testing Positive for Benzodiazepines?
A positive test days after the last dose often reflects a long-acting benzo, active metabolites, chronic use, or slower metabolism from age, liver function, or other medications. Detection windows vary significantly between people. If a result is unexpected, a doctor can order confirmatory testing to identify the specific benzodiazepine.
Getting Information and Support
Knowing how long benzos stay in your system, and how benzos affect the body, can help you avoid dangerous combinations and plan any changes safely with your prescriber. A pharmacist can also explain how your other medications might affect a benzodiazepine. If benzodiazepine addiction has developed, outpatient care can support the recovery process.
The Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-4357 is free and confidential, and anyone in a mental health or suicide crisis can call or text 988. For signs of overdose, call 911. Simple Path Recovery provides outpatient addiction treatment in Pompano Beach for adults.
This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Do not stop or change a prescribed medication without talking to your prescriber. If you are in crisis, call or text 988; for signs of overdose, call 911.
Sources
- U.S. Food and Drug Administration. FDA requiring Boxed Warning updated to improve safe use of benzodiazepine drug class. Drug Safety Communication, September 23, 2020 (content current as of October 2, 2020). https://www.fda.gov/drugs/drug-safety-and-availability/fda-requiring-boxed-warning-updated-improve-safe-use-benzodiazepine-drug-class
- Viatris Specialty LLC. XANAX (alprazolam) tablets Prescribing Information, sections 10 and 12. Revised April 2024. DailyMed, National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bb5cf72e-3a41-41a8-9a38-80f974eca33f
- Temte V, et al. An Experimental Study of Diazepam and Alprazolam Kinetics in Urine and Oral Fluid Following Single Oral Doses. Journal of Analytical Toxicology. 2019;43(2):104-111. doi:10.1093/jat/bky062. https://pubmed.ncbi.nlm.nih.gov/30517712/
- ARUP Consult. Drug Testing: Specimen Selection, Detection, and Confirmatory Testing. https://arupconsult.com/content/drug-testing
- U.S. Food and Drug Administration. New Safety Measures Announced for Opioid Analgesics, Prescription Opioid Cough Products, and Benzodiazepines. August 31, 2016. https://www.fda.gov/drugs/food-and-drug-administration-overdose-prevention-framework/new-safety-measures-announced-opioid-analgesics-prescription-opioid-cough-products-and
