Drug testing

Workplace drug testing is conducted to detect the presence of controlled substances, illicit drugs, alcohol or some kinds of prescription medication. It is part of many drug-free workplace programs meant to create a safe environment for all employees.

A drug testing program for employment can happen in federal and non-federal offices depending on the employer mandates, but they should always comply with local, state and federal laws.

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What are the different types of workplace drug tests?

Drug tests will vary based on the specific drug being tested for and what kind of samples are collected as outlined in the testing program.

The main methods of drug testing for the workplace:

Alcohol testing (breath-alcohol test). In alcohol testing, a person breathes into a device that shows the level of alcohol in the blood at that time, or Blood Alcohol Concentration (BAC). The legal limit for driving in most states is a BAC of 0.08, but for Department of Transportation regulations, a BAC of greater than 0.04 may be grounds for removal. Alcohol testing only tests for alcohol substance abuse, not other substances.

Blood tests. A blood test measures the actual amount of drugs or alcohol in the blood at the time of testing. Blood testing has a shorter detection period, and therefore is a better indicator of recent consumption.

Hair testing. A hair test is the least invasive method of drug testing, and it also provides a longer detection window. A sample of your hair is taken to determine an employee’s drug history within the past 90 days. Hair testing can only show past use of a substance, and does not test for alcohol use.

Oral sample/saliva or fluid sample. A swab of the inner cheek is taken to collect saliva (oral fluids). This method is most beneficial to determine current drug use or impairment, and often is better at detecting use of marijuana, cocaine and amphetamines.

Sweat sample. A skin patch, much like a band-aid, is applied to the skin and worn over time to collect sweat from the employee which can be tested to determine substance use. This is a simple method of drug testing, and is mainly used for parole or rehabilitation rather than workplace drug tests.

Urine testing (urinalysis). A urine sample (30-45 mL) is collected from employees and examined for metabolites. A urine test is generally recommended to check for illicit and prescription drug abuse since alcohol passes through the system much quicker.

When does drug testing happen?

Annual physicals. As part of an annual physical exam, employees may be tested for alcohol or drug use and required to send the information to employers as part of the exam.

DOT (Department of Transportation) drug testing. The Federal Motor Carrier Safety Administration (FMCSA) requires that anyone with a commercial vehicle license (CDL) undergo regular drug and alcohol testing. If you have a CDL, your employer may conduct random drug tests, annual drug tests or other tests as indicated to comply with FMCSA regulations.

Pre-employment tests. Prospective employees may be required to pass a drug test for employment.

Post-accident tests. If an accident happens in the workplace, a drug test can be used to determine if alcohol or drug abuse was the cause.

Post-treatment tests. If employees are returning to work from any kind of rehabilitation program, post-treatment testing can ensure they remain drug free and help encourage them to refrain from substance abuse.

Reasonable suspicion tests (random drug testing). If an employee is showing any signs of being unfit for duty, or exhibits a pattern of unsafe behavior or substance abuse, they may have to take a random drug test to protect the safety and wellbeing of the employee and coworkers.

Drug test results

Depending on the drug test administered, results can take anywhere from 24 hours to a few days.

To ensure the accuracy of the drug testing services, the samples will be sent to an HHS-certified laboratory. A Medical Review Officer (MRO) – a licensed physician trained in substance use disorders – will interpret the test results along with the employee’s medical history and other relevant information.

After the MRO reviews the samples, they will submit the results to the employer.

Negative results indicate that the employee has not consumed alcohol or illicit drugs in the recent past, while a positive test result does indicate some form of recent substance use.

If the tests indicate positive use of substances, the employee may be referred for treatment, rehabilitation or disciplinary action.

Workers discussing drug test results

What substances are identified in a drug test?

While a drug test may target only one drug, most tests typically identify multiple drugs using the same sample. Drug testing is commonly used to detect the following five categories of illegal drugs:

  • Amphetamines
  • Cocaine
  • Marijuana
  • Opiates
  • Phencyclidine (PCP)

Drug tests can also reveal use of the following recreation or prescription drugs:

  • Barbiturates
  • Benzodiazepines
  • Ethanol (alcohol)
  • Hydrocodone
  • MDMA (Ecstasy)
  • Methadone
  • Methaqualone
  • Propoxyphene

FAQs about workplace drug testing

What is a drug test?

A drug test is a medical test that looks for evidence of drug use or drug metabolites in a person’s blood, urine or other biological samples.

Are drug tests and drug screens the same thing?

Although the terms can be used interchangeably, a drug screen is different from a drug test. A drug screen is a cost-effective approach with faster results. However, a drug screening can sometimes give false-positive readings to certain drugs. A drug test offers more reliable and accurate analysis of substance use and is preferred over screening.

How long do drugs stay in the body?

Different drugs stay in the body for different amounts of time. In addition, a variety of factors determine how long drugs last in someone’s system such as:

  • Body Mass Index (BMI).
  • Weight.
  • Metabolic rate.
  • Hydration levels.
  • Drug tolerance.
  • Frequency of drug(s) use.
  • Medical conditions that prevent drug elimination.
  • Type and amount of drug(s) used.
  • The half-life of the drug(s).
  • The presence of other substances in the body.
How long does it take to get drug test results?

Depending on the type of drug test administered, results can take anywhere from 24 hours to a few days.

What are some common methods of drug testing?

Urine testing is the most common method of drug testing, but drug tests can also be conducted on samples of blood, hair or saliva.

When do you need a workplace drug test?

Employers can sometimes require a drug test during pre-employment screening, as well as during active employment for either random drug testing or when drug use is suspected.

What types of drugs are detected in drug tests?

Drug testing is commonly used to detect these categories of illegal drugs: Amphetamines, Cocaine, Marijuana, Opiates and Phencyclidine (PCP).

What does positive and negative mean on a drug test?

A positive result on a drug test reveals that the individual had a detectable quantity of a substance in their body, whereas a negative result indicates that the substance was not detectable.

Can medications cause false positive drug test results?

Yes, some prescription and over-the-counter medications can cause false positive drug test results. It is important to inform the tester of any medications you may be taking to avoid any confusion.


The Substance Abuse and Mental Health Services Administration (SAMHSA). Drug Testing Resources for the Workplace – https://www.samhsa.gov/workplace/drug-testing-resources

MedlinePlus: National Library of Medicine. Drug Testing – https://medlineplus.gov/lab-tests/drug-testing/

National Center for Biotechnology Information (NCBI): National Library of Medicine. Drug Testing – https://www.ncbi.nlm.nih.gov/books/NBK459334/