Common Drugs and How Long They Stay in the System

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Common Drugs of Abuse

There are many misconceptions and myths surrounding the process of detecting common drugs through a drug test. Websites that purportedly help job applicants “beat the system” have a wide range of numbers for how long drugs stay in the system and most rely on common assumptions.

“Marijuana stays in the system for a month”

“Cocaine is out of your system within a day”

These are all common timeframes thrown around.

This article will shed some light on the most common drugs of abuse and how long they tend to stay in the system. As an employer, it is important for you to know this information. Drug testing detection windows will have an impact on the accuracy of your drug testing program and should influence your drug testing policy.

Drug metabolites

When the drug testing lab is examining a specimen to determine drug use, they are looking for traces of drug metabolites – not the drug itself. Drug metabolites are the chemical byproducts of a drug being metabolized in the body. Some drugs may also contain multiple metabolites.

While the chemical makeup of a drug may dissipate quickly, the remaining metabolite may linger much longer. This explains why drugs can be detected long after their effects have worn off.

Metabolite cut-off levels

It is possible to have trace amounts of a drug metabolite from foods or medications. To prevent false-positives, drug testing labs institute cut-off levels for drug metabolites. For a drug test to be determined positive, they must pass the cut-off threshold. The following chart, courtesy of Alere, illustrates how cut-off levels impact the detection window.

drug testing window of detection

General facts about drug metabolism

The important thing to note when discussing drug metabolism and detection windows in drug testing is that we can only speak in generalities. This is because each person’s body metabolizes chemicals at a different rate. Habitual use also impacts the detection window. Each of the common drugs of abuse listed below have detection windows that reflect that.

Detection period is also dependent on the type of testing being conducted. Urine tests have a much longer detection window than saliva. Hair testing has the longest detection window, but serves mainly to determine habitual use – not individual instances.

Common drugs of abuse


3-30 days*

According to a recent Index Report by Quest Diagnostics, marijuana is the most commonly detected substance in positive drug tests by a large margin.  Marijuana positive drug tests make up 2.4% of all urine drug tests. The uniquely long detection window for habitual marijuana use may be a large contributor to that margin.

Marijuana has a very wide detection window in drug tests. A single use may be undetectable in as little as three days, while long term habitual use can result in a detection window upwards of 30 days. Here is a complete breakdown of the detection windows:

  • Single use = 3 days
  • Moderate use = 5-7 days
  • Daily use = 10-15 days
  • Long term habitual use = 30+ days


1-3 days

Amphetamines (uppers) are the second most commonly detected drug in positive drug tests at 1.11% of all drug tests examined. They are common from many different sources that include prescription medications. However, positive drug tests do not include tests where a medical prescription is provided by the donor and the metabolite levels coincide with the amount prescribed.

Amphetamines have one of the shortest detection windows.


1-14 days (Oxazepam 4-6 weeks)

Benzodiazepines (downers) include drugs like sleeping pills, tranquilizers, Xanax, and Valium. Positive drug tests within this category make up for .68% of all drug tests.

Benzodiazepines have a detection window from 1-14 days – depending on the specific metabolite being detected and frequency of use. Within the Benzodiazepine family, Oxazepam is an outlier with a detection window of 4-6 weeks.

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1-3 days

Opiates have one of the shortest detection windows for urine testing. The opiates family includes drugs such as morphine, heroin, oxycodone, and hydrocodone – basically, the painkillers. Many areas throughout the country are reporting increased opiates addiction in the last few years. As such, the number of positive drug tests has also been steadily increasing.


1-7 days

Cocaine is commonly attributed as being the drug that has the smallest detection window. While the detection window for cocaine can be as little as one day, it can also be up to seven days. As with many drugs, this is dependent on factors like individual metabolism rate and frequency of use.

Final thoughts

Knowledge is power. Knowing the relatively small detection windows of some of these commonly abused drugs, let’s consider how this information could impact your drug testing policy. Mostly, this means that your drug testing practices are going to need to be on a short timeline (if they aren’t already).

For random or ‘for cause’ drug testing programs, you should consider the impact of short detection windows in some drug metabolites. These short detection windows will make it difficult to have an accurate drug test if the donor has more than one day to provide a sample.

The same applies to pre-employment drug tests as well. If you give applicant’s a couple weeks to take their test, you are effectively giving them time to sober up before taking the test.

The bottom line is that you should ensure that your applicants and employees are taking their drug tests in a timely manner. This will greatly improve the accuracy of your drug testing program.