What is a drug test?

Drugs are chemical substances that can change how your body and mind work. A drug test looks for signs of illegal drugs or certain prescription and/or over-the-counter (OTC) medicines that can be misused. The test is usually done with a sample of your urine (pee). Less commonly, drug testing uses a sample of your blood, saliva (spit), hair, sweat, fingernails, or breath. The purpose of a drug test is to look for drug use and misuse, which includes:

• Using any illegal drugs, such as:
  • Anabolic steroids.
  • Cocaine.
  • Club drugs.
  • Heroin.
  • Inhalants.
  • Marijuana (cannabis, THC).
  • Amphetamines, such as methamphetamines and Ecstasy (MDMA).
  • Phencyclidine (PCP)
• Misusing prescription medicines, including opioids (such as codeine, oxycodone, morphine, and fentanyl), barbiturates (such as phenobarbital), and benzodiazepines (such as alprazolam). This means taking prescription medicines in a different way than your health care provider prescribed. This includes:
  • Taking a medicine that was prescribed for someone else.
  • Taking a larger dose than you are supposed to.
  • Using the medicine in a different way than you are supposed to. For example, instead of swallowing your tablets, you might crush and then snort or inject them.
  • Using the medicine for another purpose, such as getting high.
• Misusing over-the-counter medicines, such as dextromethorphan (DXM) and certain laxatives. This includes using them for another purpose or in a different way than you are supposed to.

A drug test can also check your urine or blood for signs of alcohol use.

Drug tests can find signs of drugs that you took hours to several days or more before the test. How long a drug lasts in your body depends on:

• The type of drug
• How much you used
• How long you were using it before the test
• How your body reacts to the drug

Other names: drug screen, drug test, drugs of abuse testing, substance abuse testing, toxicology screen, tox screen, sports doping tests

What is it used for?

Drug testing is used to find out whether you have been using or misusing one or more drugs or prescription/OTC medicines. It can't diagnose a drug use disorder (addiction).

A drug test may be used for different purposes, including:

• Employment. Employers may require that you pass a drug test before they will hire you. The testing may be part of a drug-free workplace program. After you're hired, they may test you to check for on-the-job drug use. If you have a work accident, you may be tested to see whether drugs or alcohol were involved.
• Sports. Professional and other athletes are often tested for drugs that are used to improve performance, such as anabolic steroids that help build muscle.
• Substance use disorder treatment. Drug testing may be used to monitor treatment in programs for drug or alcohol use disorder (AUD).
• Legal evidence. Testing may be part of a criminal or motor vehicle accident investigation. Drug screening may also be ordered as part of a court case.
• To prevent prescription drug misuse. If you take a prescription medicine that can be addictive, such as opioids for chronic (long-term) pain, your provider may order a drug test to make sure you're taking the medicine correctly.
• To detect over-the-counter (OTC) drug misuse. If your provider suspects that you are misusing an OTC medicine, such as a laxative or cough medicine, they may order a drug test to know for sure.

Drug testing may be scheduled ahead of time or done randomly without notice.

Why do I need a drug test?

You may be asked to take a drug test for a job, to participate in certain organized sports, or as part of a police investigation or court case. In a hospital emergency room, a provider may order a drug test if you have signs of a possible drug overdose. Newborns can also be tested for possible prenatal exposure to illegal drugs.

What happens during a drug test?

Drug testing may be done in many different locations, including labs, hospitals, drug treatment centers, and workplaces.

Urine is the most commonly used sample for drug testing. You will be given instructions for how to collect your sample. In certain cases, a health care professional or other person may need to be present while you provide your sample. This is to make sure the urine is yours and isn't contaminated with anything that might affect the test results.

If a blood sample is used to test for drugs, a health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

If a saliva sample is used to test for drugs, your provider will take a saliva sample from your mouth using a swab. They will roll the swab in your mouth or hold it under your tongue for about 2 minutes until it is soaked with saliva. They will then either place the swab in a tube and send it to a lab for testing or test it immediately using a handheld device.

In some cases, a health care professional may test your hair, fingernails, or sweat for signs of drug use, though these testing methods are not as commonly used.

A health care professional may also use a breath test to see if you've been drinking alcohol. For this test, you will blow into a tube connected to a small device that will measure your blood alcohol content (BAC).

Will I need to do anything to prepare for the test?

Be sure to tell the testing professional if you are taking any prescription drugs, over-the-counter medicines, or supplements, because these substances may affect your test results. Also, you should avoid foods with poppy seeds, which can show up as opiates in a drug test.

Are there any risks to the test?

There are no known physical risks to having a drug test. But if drugs show up in your results, it may affect your job, your eligibility to play sports, the outcome of a legal matter, or other parts of your life.

Before you take a drug test, make sure you know:

• What you are being tested for
• Why you are being tested
• How the results will be used

If you have questions or concerns about a drug test, talk with your provider or the person or organization that is asking for the test.

What do the results mean?

If a drug test result is positive, it means that one or more drugs were found in amounts that suggest drug use or misuse. If you have a positive test result, you'll usually have a follow-up urine test to make sure the first test was correct. That's because the type of urine testing that's often done first can have false positive results.

A false positive means that the test showed you had a drug in your sample when it really wasn't there. False positives can happen if the test reacts with other chemicals in your body from certain over-the-counter medicines, prescriptions, and foods.

The follow-up drug test after a false positive result is called a confirmatory test. It is a more sensitive test that provides more accurate results.

If a drug test result is negative, it means that either:

• The drugs that were tested were not found in your sample.
• A very small amount of drugs was found, but not enough to count as a positive test result for drugs.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about a drug test?

If you test positive for a legal drug prescribed by your provider, your employer can't punish you, unless the drug is affecting your ability to perform your job.

If you test positive for marijuana and live in a state where it is legal, employers may still be able to punish you in some states. Employers may do this because they want a drug-free workplace. Also, marijuana is still illegal under federal law.

You can buy home tests for many illegal and prescription drugs. There are two types of tests:

• At-home tests let you do the entire test at home and get rapid results. But if the test result is positive for drugs, you'll need to have a follow-up lab test to check the accuracy of the result. Before you buy an at-home test, check to see if it includes a kit for collecting a sample, often urine or saliva, to send to a lab in case the home test is positive.
• A self-collection test has a kit for gathering urine, saliva, or another type of sample to send to a lab for testing.

When using home tests, be careful to follow all the instructions. It's best to talk with your provider about using home drug testing so you can decide if it's right for your situation.