AfterOurs Clinics - Colorado
AfterOurs Clinics - Colorado

Drug Screening

Lab practitioner doing some testing

Drug screening is used to detect the presence of certain substances inside the body. These screening tests cannot detect the presence of every drug in the body.  The tests only detect substances when they are present inside the body above predetermined levels.

Drug screenings are frequently used to look for the presence of one or more illegal drugs in blood, urine, saliva, or sweat. Urine screening is the most common and widely used drug screening test. Drug screening is widely performed for the following drugs:

  • Opioids
  • Marijuana
  • Cocaine
  • Steroids
  • Barbiturates
  • Phencyclidine/PCP

For drug screening, urine and/or blood samples are collected, and then they are sent to drug testing laboratories, where the samples are assessed for the presence of drug use or abuse.  Results are typically available in two to three days.


Drug screening may be used for the following purposes:

  • Employment: Employers may test candidates before hiring them for a certain position or they may arrange quarterly or annual drug screenings to check for on-the-job drug use.
  • Sports: Professional players may need to take a drug screening test before playing in their sport to make sure they have not taken any performance-enhancing drugs.
  • Opioid use: Opioids are the most abused drugs, so screenings are usually performed on patients who are using such medication to rule out Improper medication use
  • Forensic purpose: Drug screening may be a part of a criminal activity or motor vehicle accident investigation.
  • Military entry tests or routine checkups


Drug screening results can come out to be false-positive or false-negative depending on various factors.

False Negative

Urine testing is more likely to produce a false-negative – where the drug is present, but the lab report does not detect its presence.  Measures are usually taken to ensure that people getting drug tested do not provide invalid samples. For example, people may try to submit another person’s urine sample that is free of drugs.  In some cases, people try to defeat urine samples by drinking a large volume of water or by administering diuretics before taking the urine screening test. In this case, the sample would not be accepted because the specific gravity of the urine would be too low and therefore could not be used to identify the presence of any drug.  A new sample would be required to run a valid drug test.

False Positive

False-positive results can be produced when the candidate is taking prescription or nonprescription drugs or from eating certain foods.  Poppy seeds may produce false-positive results for opioids. Similarly, tricyclic anti-depressants or pseudoephedrine can produce false-positive results for amphetamine.  In  some cases, ibuprofen produces false-positive results for marijuana.

Before drug screening, it is advised not to take any drug or eat any food that can interfere with the results of the tests. In most cases, if there is a valid explanation for a false-positive, the drug test can be taken again.

Contact us

In case of urgent medical care assistance, AfterOurs Urgent Care offers immediate telemedicine services, where medical providers are available to offer assistance. Anyone who experiences signs and symptoms requiring urgent medical attention can simply book their appointment with AfterOurs Urgent Care to directly talk to an expert. If your medical issue is not appropriate for telemedicine, we will let you know and refer you to an in-person facility.

When to visit a doctor:

If you experience swelling on the lining of the mouth, lips, or nose, then you should seek immediate medical assistance.

Treatment for hives is available at AfterOurs Urgent Care. 

For more information regarding Hives, see the following website: