Drug Test: What It Is, Purpose, Procedure & Types - Cleveland Clinic

21 Jul.,2025

 

Drug Test: What It Is, Purpose, Procedure & Types - Cleveland Clinic

What is a drug test?

A drug test uses a biological sample (such as blood or urine) to detect the presence or absence of a legal or illegal drug. Drug tests are ordered and performed in a variety of settings with a variety of techniques.

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Drugs include legal substances such as alcohol and tobacco, as well as over-the-counter medications, prescription medications and illegal substances. A single drug test can’t determine the frequency and intensity of substance use and, thus, can’t distinguish casual substance use from substance use disorders.

Your body metabolizes (breaks down) various drugs at different rates, so the timeframe for detecting certain drugs in your system can be very specific and vary widely from substance to substance.

Urine drug testing (UDT) is the most common test for detecting drugs.

When would I need a drug test?

You may need a drug test for several reasons. The most common use of drug testing is in the workplace. Employers may require a drug screening for various reasons, including:

  • Before hiring an applicant.
  • During someone’s employment — an employer may randomly or periodically require drug testing after they hire an employee.
  • When drug use is suspected based on signs and symptoms observed in the workplace.
  • After an employee has an accident or incident while working.

Another common use of drug testing is for the diagnosis, treatment and monitoring of alcohol use disorder and substance use disorder. As a tool for monitoring, drug testing can help determine treatment adherence, monitor abstinence and detect early relapse.

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You may need this testing for court-ordered treatment programs, as a term of probation or while participating in a substance use disorder treatment program.

Other uses for drug testing include:

  • Medical testing and diagnostics: People may be tested for drug use to help determine the cause of their symptoms or in emergencies when healthcare providers suspect a potential drug overdose or poisoning.
  • Legal testing: There are several reasons drug testing may be required for legal purposes, including collecting potential evidence of a crime, investigating cases of child abuse or endangerment and determining if a person is under the influence of alcohol or other substances while driving.
  • Monitoring for prescription drug misuse: If you take a prescription drug with high addiction potential and/or the potential for misuse, such as opioids for pain, your provider may request a drug test to check the amount of the drug in your system.
  • Athletic testing:Professional athletes often have to take a drug test to screen for drugs or other substances considered performance-enhancing.

What are the types of drug tests?

There are several kinds of drug tests based on the biological sample they use and the types of drugs they detect.

Different types of drug tests based on the sample used include:

  • Urine drug testing (UDT): This is the most common drug test. It requires a sample of your urine (pee). Urine drug tests are most commonly used to detect alcohol, amphetamines, benzodiazepines, opiates/opioids, cocaine and marijuana (THC).
  • Blood drug testing: Healthcare providers mainly use this type of test in emergencies. It’s also typically used to detect alcohol (ethanol) levels because it can provide a precise level.
  • Hair follicle drug testing: A hair sample can provide information on substance use over time. Scalp hair has a detection window of three months, while slower-growing body hair has a detection window of up to 12 months. The results can vary based on the characteristics of each person’s hair. Hair testing can detect the use of cocaine, phencyclidine (PCP), amphetamines, opioids and 3,4-Methylenedioxymethamphetamine (MDMA).
  • Breath drug testing: This is primarily used to detect recent alcohol consumption. The result is called a breath alcohol concentration (BrAC). Officials often use it to estimate a person’s blood alcohol content (BAC). However, BrAC can sometimes overestimate or underestimate the BAC. Recent research has focused on the potential use of breath testing for detecting cocaine, marijuana, benzodiazepines, amphetamines, opioids, methadone and buprenorphine.
  • Sweat drug testing: Sweat testing involves wearing an absorbent pad on your skin that’s collected and tested after a certain amount of time. The results provide information on how much of a substance the person consumed over the entire time that they wore the pad. Sweat testing gives a detection window of hours to weeks.

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What will a drug test detect?

When a drug enters your body, your gastrointestinal tract absorbs and distributes it to the rest of your body. Your liver and other organs metabolize the drug (break it down). Metabolic processes cause the drug to turn into different chemicals, called metabolites. After a certain amount of time, the drug and/or its metabolites leave your body, mainly through your urine.

A drug test screens for certain drugs and/or their metabolites in a biological sample (such as urine or blood).

The metabolic processes happen at different speeds for different drugs. Because of this, each drug and its metabolites have a different timeframe in which a drug test can detect them.

For some drugs like amphetamines, the main (parent) drug will be detected in urine. For most other drugs, metabolites will be detectable for a longer time than the main drug.

A drug test may look for only one drug, but most drug tests often test for multiple drugs with one sample. Although the drugs included in a drug panel test vary based on the reason for the test, the most common panel used to evaluate people for illegal drug use detects the presence or absence of five substances:

  • Amphetamines.
  • Cocaine.
  • Marijuana.
  • PCP.

Other commonly tested substances include:

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  • Alcohol (ethanol).
  • Antidepressants.
  • Barbiturates.
  • Benzodiazepines.
  • Fentanyl.
  • Heroin.
  • Hydrocodone.
  • Methadone.
  • Methamphetamine.
  • Morphine.
  • Nicotine and cotinine.
  • Oxycodone.

Are at-home drug tests available?

Yes. Some kits can test urine samples in the privacy of your own home. Some kits may use breath, saliva or hair instead. The accuracy of these products is variable. They generally are less sensitive than the formal tests done in a laboratory. This means that a home test could be negative, but a laboratory test could be positive with the same sample.

The American Academy of Pediatrics cautions parents against drug testing their children at home. Research studies have shown that at-home testing doesn’t reduce drug use. At-home testing also comes with the potential for misinterpreting results, which may negatively affect the relationship between children and parents.

How do I prepare for a drug test?

There’s nothing you need to do to prepare for a drug test.

Drug testing can be an emergency test, a scheduled test or it may be conducted randomly (for example, to meet ongoing employment requirements).

Contact us to discuss your requirements of Drug Of Abuse Tests. Our experienced sales team can help you identify the options that best suit your needs.

Depending on the circumstances, you may be asked to identify medications or supplements you’re taking.

What should I expect during a drug test?

Drug testing can be performed from small samples of your blood, hair, saliva, breath or, most commonly, your urine (pee).

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For a urine sample, you’ll pee into a clean container provided to you. In some instances, you may need to provide your urine sample in the presence of a nurse or technician to make sure that the sample did indeed come from you.

For a blood sample, a phlebotomist will draw a small amount of blood from a vein in your arm or hand.

After the provider has collected the sample, they’ll send it to a laboratory for analysis

6 Myths About Drug Tests | US Drug Test Centers

By: Ashlee Arnold

Whether you're an employer or an employee, drug tests undoubtedly play a role in your life in some capacity. There's a lot of misinformation online when it comes to how they work and what can cause you to pass or fail a test. Let's separate fact from fiction. Here are six common myths about drug tests we need to debunk.

Myth 1: Chugging Water Can Help Trick the Test

There's this misconception that drinking an excessive amount of water leading up to a drug test can dilute your urine enough so the test won't pick up on any substances in your system. People will also do this in an attempt to flush out their system as quickly as possible to rid it of any illegal substances completely.

A word of warning to anyone considering trying this: while it can make it harder to detect substances in your body, it will likely be obvious you're trying to cheat the test.

Here's why.

There are specific markers drug tests look for to determine that the specimen was indeed genuine. Aside from specific substances, something else most drug tests measure is the level of creatinine in your body. Creatinine is a byproduct of digestion. When you drink a lot of water, your creatinine goes up. This is a sign to drug test professionals that an individual consumed an excessive amount of water.

At best, a person who attempts this will end up with a negative dilute result, which means the employee should be asked to submit another urine sample or a test that's harder to cheat, like a hair follicle drug test for alcohol or drugs.

Myth 2: Diuretics Can Help You Pass a Drug Test

Similar to trying to flush their system out with water, some people will take diuretics — any substance that increases your body's urine production — in an attempt to empty or rid their body of any illegal drugs. Diuretics can be over-the-counter pills or beverages like coffee and tea.

While diuretics might dehydrate you, in the process, they will also alter other naturally occurring chemicals in your body, raising a red flag to those conducting your drug test. In other words, it will likely be obvious the person took diuretics.

Myth 3: You Can Fail a Drug Test Due to Secondhand Smoke

What if you're not smoking but you're around people who are? Understandably, this might be a cause for concern for anyone who knows they could be asked to take a drug test in the near future.

Rest assured you're most likely safe, though. You would have to inhale an excessive amount of marijuana smoke — more than anyone probably could — in order to test positive for THC. For instance, it would likely take several hours in a very confined space with other people smoking for you to have a detectable amount of THC in your body.

Myth 4: All Drug Tests Are Created Equal

Urine tests are just one kind of drug test. They're the most common because of their affordability and ease of use. Hair tests can be even more thorough because they go back as far as 90 days and are incredibly difficult to cheat. Drug tests can also check your saliva, going back three days.

Furthermore, one must consider there are all kinds of drug test panels — like the 5 panel drug test and 10 panel drug test. US Drug Test Centers can even customize a panel specifically for you, so it meets your needs.

Myth 5: You Can Beat a Drug Test With Synthetic Urine

Some people will try to beat a drug test with synthetic urine — urine they'll typically purchase and swap with their own.

However, similar to how labs can determine if a urine specimen has been diluted, there are specific markers they look for to determine if it's not the individual's real urine, like the pH level and its temperature. When these numbers are outside their normal ranges, drug test professionals know they're looking at synthetic urine.

Myth 6: You Can Fail a Drug Test After Eating Poppy Seeds

While poppy seeds do come from the opium poppy, it's highly unlikely that you could ever consume enough to trigger a drug test. Consuming them won't make you high and could probably never cause a pharmacological effect.

To ensure your drug and alcohol testing goes accordingly, you need to work with a company you can trust. US Drug Test Centers always works with an MRO and uses SAMHSA-certified laboratories. Plus, we have more than 20,000 locations around the United States, meaning that you never need to travel more than a few miles for drug and alcohol screening.

We offer a variety of panels, which you can view on our website. Don't see the one you want? Get in touch and tell us your needs, and we'll customize a panel just for you.

You can order a test online 24/7, from anywhere, for anywhere. Contact us today.

If you want to learn more, please visit our website HAV Rapid Test.