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How Do Drug Tests Work?

There are a variety of reasons why you might need to drug test yourself or even an employee. The world is home to many harmful and illegal substances, and we don’t want our employees driving cars, operating machinery, or helping others if they are under the influence.

Can you imagine if your surgeon had a recreational drug habit on the side? That wouldn’t be good for the surgeon or your health. This is why drug tests are crucial, especially in industries where substance abuse is most common.

Drug tests are an integral part of competitive sports as well. Professional and collegiate athletes must abstain from illegal drugs and performance-enhancing drugs and chemicals, including steroids that can give them an unfair advantage over their competition. As we pointed out in a previous blog, there are various types of drug tests out there, each testing for something different.


The Different Types of Tests

There are six different types of drug tests available depending on the situation. Currently, oral, urine, blood, breathalyzers, and hair follicle tests are the most common. Perspiration drug tests are newer to the market and less reliable, and less common. Let’s take a closer look at the four most commonly used drug tests on the market.


Urine Tests

Urine tests are the most widely administered drug test on the market. They are convenient because they are a non-invasive option and require minimal equipment. They are also highly effective. But why are they so popular?

Despite the unifying name, there is more than one type of urine test. Each one has pros and cons, but typically false positives are the primary concern. To eliminate this issue, the different testing methods usually get combined for an easier experience. The process involves a detailed level of steps to ensure accuracy.


  1. The urine sample is split into two; one for an initial screening and a second for verification if the first sample tests positive.
  2. The first sample is screened with an immunoassay process. The initial test screens for drugs, urine creatine (also called metabolites), and pH so it can detect any attempts at tampering.
  3. If the sample is positive, further steps are required to confirm.
  4. The second sample gets tested using a GC-MS process.
  5. A drug-specific test gets performed. For example, if you tested positive for opiates, a test for what type, like hydrocodone, can be performed next.
  6. The results are giving to an MRO (medical review officer) and reviewed for accuracy.
  7. If the test is negative, the organization that requested the test is informed.
  8. If the test is positive, the MRO will contact the requester of the test to verify details and make sure there isn’t a relevant medical reason for the positive result.


The laboratory process may seem complex, but they are cost-effective and relatively accurate. But how accurate? It all depends on how long a drug can be detected in a urinalysis. This answer varies based on recreational use. For chronic users, the detection window is typically much longer:

  • Alcohol- 6-24 hours
  • Amphetamines- 1 to 3 days
  • Methamphetamine- 3 to 5 days
  • Benzodiazepines- 7 days
  • Marijuana- 7-100 days depending on the level of use
  • Cocaine- 2-5 days


Saliva Tests

After urine tests, oral drug tests are the most common. The saliva test is simple and less embarrassing than a urine test for some. Here, the test administrator uses a standard swab to collect a saliva sample from the inner cheek. Saliva tests are more difficult to tamper with and can be administered locally with minimal staff, making them the ideal test for quick testing events.

Unfortunately, saliva tests don’t offer the same detection level that urine tests do. They only detect a user’s most recent drug use, usually within 48 hours. This is because the test only evaluates any remaining drugs present in your salvia and some drugs are more challenging to detect than others with this method. Oral tests are most common for random testing and after a work-related safety incident because of their short drug detection window. So, how long can oral tests be an effective way of catching drug use? 

  • Alcohol- 12-24 hours
  • Amphetamines- 12 hours
  • Methamphetamine- 1-3 days
  • Benzodiazepines- 6- 48 hours
  • Marijuana- 2-24 hours
  • Cocaine- 2-10 days


Blood Tests

Unlike urine and saliva tests, blood tests are invasive and a little bit painful. Urine tests can be tampered with, but blood tests need to be done in a laboratory or with a licensed phlebotomist making them nearly impossible to tamper with. Much like urine detection, blood testing involves blood specimens using immunoassay screening. 

You can perform a blood test to detect just about any substance, so it is commonly used when criminal activity is suspected. Blood tests are only accurate while the substance is present in someone’s system, so anything over 48 hours and a blood test can be significantly less accurate.

A blood sample drug screening seems pretty irrelevant when considering that the detection window is almost identical to the screening window for saliva tests, but with added pain level and higher cost thrown in.

  • Alcohol-12-24 hours
  • Amphetamines- 12 hours
  • Methamphetamines-1-3 days
  • Benzodiazepines-6-48 hours
  • Marijuana- 2-3 days
  • Cocaine-2-10 days


With this tiny detection window, a blood test seems almost unjustifiable. The average urine and saliva drug test costs an employer between $30 and $60, while a blood test can cost more than $200.


Hair Follicle Testing

This is the most effective tool out there for long-term detection. Except for LSD, all drugs stay in a person's system for at least 90 days after use. LSD is only detectable for up to 4 days.

The idea that drugs are present in urine, blood, and salvia isn’t all that surprising, but your hair? Your hair is where drugs are the most detectable. When you use illegal substances, small amounts of chemicals are deposit into the cortex of the strand of each hair. And even as the hair continues to grow, those deposits stay there.

Although highly beneficial, these tests are expensive and difficult to process, so they are typically used only for special situations like joining the police cadets. While you need a laboratory for processing, they can be ordered online and submitted from home. Here is the process: 

  1. The test administrator will take between 100-120 hairs from your head to gain an accurate result. Body hair is also acceptable, and despite common misconceptions, you can dye your hair without it affecting the test.
  2. Hair is taken back to the lab and washed.
  3. The hair is then dissolved in solvents.
  4. The liquid is then analyzed by mass spectrometry to search for drug metabolites and the same chemicals urine tests look for.

 Unlike with urine tests, you can’t just abstain from drugs to pass a hair follicle screen, recent use or not; if you’ve used illegal substances in the past several months, you’ll likely fail the test.


Countrywide Testing

Pre-employment screening can be nerve-wracking. If you are concerned about passing a drug test, consider preemptively screening yourself at home. And if you need help finding at-home drug tests, Countrywide Testing can help!

We are an online realtor of drug and alcohol testing and lab services. Our products include pregnancy tests, medical supplies, multi-panel drug tests, and more. We also work with a SAMHSA, ISO, CLIA, and CAP licensed laboratory, which means you can rest easy knowing your samples get processed by a government-trusted facility.

 Shop our store now or call us at (469) 356-8607 to find the right product.