Urinalysis JarsValium (diazepam) is detectable on standard urinalysis drug tests for a considerable period of time, especially when compared to other medications in the class. Most studies indicate that Valium will be detectable for up to 30 days, and even longer if an individual has taken it consistently for extended periods of time.

Why Is Valium (Diazepam) Detectable On Drug Tests For So Long?

Valium (diazepam) is a benzodiazepine medication, noted for its very long half-life when compared to other medications in the class. "Half-life" refers to the time it takes for 50% of a drug to be metabolized and eliminated from the body. Drugs with a long half-life tend to be detectable on standard urine drug tests for a longer period of time than drugs with a short half-life.

The active ingredient in Valium, diazepam, has a half-life of around 48 hours while one of its metabolites (i.e. metabolism by-product), N-desmethyldiazepam, has a half life of nearly 100 hours. In addition, diazepam can accumulate in the body after prolonged and consistent dosing, which may prolong the half-life even further.

To determine how long diazepam is detectable on a drug test, you need to consider the metabolite N-desmethyldiazepam, which is often tested for. Most sources state that N-desmethyldiazepam will be detectable in your system on urine tests for up to 30 days, if not longer.

When we consider the 100 hour half life of N-desmethyldiazepam, this detection period makes sense. A general rule of thumb is that it takes around 5 half-lives for a drug to be completely metabolized and eliminated from the body. This translates to 500 hours, or around 21 days for the diazepam metabolite N-desmethyldiazepam. Considering that diazepam can accumulate in the system, prolonging the half life, up to 30 days is a good estimate for how long it lasts in your system.

How Long Is One Tablet Of Valium (Diazepam) Detectable On A Drug Test

In regard to how long a single dose of Valium will be detectable, it could still be detectable for up to 30 days on a urine drug. It most likely won't be in your body as long as someone who takes it consistently, but as discussed above, the drug has a long half-life, regardless of how often you take it.

How Do Urine Drug Tests Work?

Diazepam, and its metabolites are excreted mainly in the urine, making standard urine drug tests a popular option for testing. Most employers and medical offices use a simple, urine based immunoassay tests. Immunoassay tests work by utilizing antibodies to react to specific drug compounds.

A positive result will occur when a specified drug is present in a test urine sample and an antibody binds to it. This produces a reaction which is recorded as a positive result.  Most immunoassay urine tests are designed to detect N-desmethyldiazepam (also known as nordiazepam), not the parent compound (diazepam).

Are False-Positives Common?

Unfortunately, the most commonly used urine drug tests (immunoassays) are subject to false positives. Often times a drug compound will react with the "wrong" antibody, producing a reaction that is recorded mistakenly as a positive result. False-positives for Valium have been reported with the following medications:

  • Oxaprozin
  • Zoloft (Sertraline)

However, if you believe a false positive did occur, the results can be confirmed or refuted using more specific tests, such as via gas or liquid chromatography with mass spectrometry. They don't rely on antibody reactions and can identify specific compounds in a given sample.

About Valium

Valium is a long-acting benzodiazepine indicated for a variety of treatments including:

  • Anxiety
  • Acute alcohol withdrawal
  • Muscle spasm
  • Seizure disorders

Valium, and all benzodiazepines, are CNS (central nervous system) depressants which produce:

  • Sedation
  • Hypnosis
  • Muscle relaxation
  • Anticonvulsant activity

While effective, benzodiazepines need to be used carefully as they can cause physical dependence and are associated with withdrawal symptoms when stopped too quickly. In addition, they cause dose-dependent respiratory depression and need to be used cautiously with other CNS depressants such as alcohol and opioids.