Last updated : May 12, 2025
The terms drug testing and drug screening are often used interchangeably and refer to a urine test. However, they are not the same. Are you curious to know the difference?
A drug test is the more reliable choice between the two because the results are proven to be the most accurate. Large corporations and government-mandated testing are more apt to require a drug test.
Drug screening, on the other hand, is the more cost-effective approach when testing employees. Parents may choose this option as well when concerned that their child is using drugs. Drug screening determines the result more quickly than drug testing too, however, they’re more likely to register a false-positive result for certain drugs.
Which drugs are we talking about?
A false positive result is what it sounds like. Despite not having taken a specific medication or illegal substance, the result registers positive.
Over-the-counter (OTC) medications can be the culprit because the chemical makeup is very similar to a specific drug.
They include:
Dextromethorphan
Brand names for this medication are Robitussin or Delsym, popular OTC cough suppressants. If in the system, these products may yield a positive phencyclidine (PCP) result.
Diphenhydramine
Benadryl is an allergy medication that contains this antihistamine. It’s often used to reduce itching and alleviate cold symptoms. It can also show up as a false positive for opioids.
Pseudoephedrine
An ingredient in Sudafed, which is used to treat nasal and sinus congestion, pseudoephedrine may show up as amphetamines or methamphetamines.
Phentermine
Approved by the Food and Drug Administration (FDA), phentermine is a weight loss medication contained in Adipex-P. It can cause false positive results for amphetamines.
NSAIDs
Nonsteroidal anit-inflammatory medications, such as Motrin, Aleve, and Advil, treat fever, inflamation, and pain. In rare instances, they trigger a false positive result for barbiturates. Daypro, another NSAID, may trigger a false positive result for benzodiazepines.
Venlafaxine and sertraline
Found as ingredients in Effexor XR and Zoloft, respectively, and, also respectively, can cause false positives for PCP and LSD.
Another antidepressant that causes false results is trazodone, a sleep aid, that ironically causes a false positive for amphetamines or methamphetamines. Both of these drugs are known for causing users to remain awake for extended periods of time.
Bupropion
Wellbutrin is the brand name attached to this medication. It can cause false positive results for amphetamines or methamphetamines.
Quetiapine
An atypical antipsychotic, quetiapine is used to treat mental health conditions, such as bipolar disorder or schizophrenia. It can yield a false positive result for methadone, an opioid.
Proton-pump inhibitors (PPIs)
Used to treat gastroesophageal reflux disease (GERD) and heartburn symptoms, PPIs, specifically pantroprazole, might cause a false positive result for tetrahydrocannabinol (THC).
Promethazine
This medication helps relieve nausea and vomiting, but can also cause a false positive for amphetamines or methamphetamines.
There could be other culprits too
There are other products that can yield a false positive result using the urine test.
They are:
- Poppy seeds—Bagels, salad dressings, and crackers are known to contain poppy seeds. Although the debate continues, it’s been determined that some poppy seed merchants fail to properly clean their product before putting it on the market. Unclean seeds contain opiate residue which, if consumed in large quantities can cause a false positive for codeine or morphine.
- Cannabidiol (CBD) products—Many CBD products contain varied levels of THC. Sometimes there’s enough to cause a positive marijuana result. And, it’s because there is enough THC in the employee’s system to pop positive.
- Hemp products—These products can also contain THC in them. Often purchased in bars and teas, consumers beware! If these products are consumed, even a few days before the test, you may have enough THC in your system to cause a positive result.
What is the reason drug screening is less reliable?
We mentioned that drug screening is the most cost-effective method for checking for drugs in the system. It’s because drug screening only involves the immunoassay (IA) test. It’s a “test strip” method and quickly determines whether or not drugs are in the system.
When companies require a drug test rather than a screening, any positive results are sent on for more extensive testing. It’s called the gas chromatography/mass spectrometry (GC/MS) test. It confirms the drug recognized is actually the drug itself and at what level it’s contained in the body.
Some states don’t allow instant testing, also known as drug screening, most likely because of the risk of a false positive result. However, the majority of employees don’t use drugs and smaller companies who use drug screening are aware of that fact. In the event of a positive drug test result, it’s a good idea to have an official test done by a SAMHSA-certified laboratory to ensure it’s the correct result.
However, if that’s your intention, be aware that you must have this stipulation written into your policies and procedures before testing employees.
Drugs don’t belong in the workplace
Whether or not someone uses drugs while on the clock if they are under the influence, they are at increased risk of causing an accident. If there is an accident, the risk of a co-worker being involved is increased as well.
Employers drug test for safety’s sake. It’s a proven fact that workplace accidents decrease when there are drug-free policies and procedures in place.
If you don’t drug test… or screen… your employees, it is worth considering. Your employees won’t mind if they don’t use drugs. And, if they do, they’re free to move on to another job, which in the big picture, is the best-case scenario.
