Last updated : June 16, 2025
Drug testing technology has come a long way over the past few decades. For instance, during the 80s, dishonest people could pass the test with drugs in their system by drinking lots of water. The diluted specimen often went undetected and the watered down sample tested negative for drug use. It was also known that eating certain foods could work in the opposite direction and cause a false positive test result.
Can either of those issues still arise today though? The short answer to that question is, “yes.”
How accurate is accurate?
The drug testing industry continues to evolve which means drug tests are becoming more accurate as time passes. Not only the test panels themselves, though, laboratory equipment becomes more and more sophisticated as well. Moreover, when working with a laboratory certified by the Substance Abuse and Mental Health Services Administration (SAMHSA), both the laboratory itself and the technicians employed there are held to the strictest of standards. Frequent inspections ensure that regulations are followed to a “t.”
Still, false positive—and negative—results do occur on rare occasion. Several factors can cause this to happen.
They include:
- Type of drug test—Tests done by SAMHSA-certified laboratories ensure the highest quality results. Other laboratories may cut corners or hire and fail to train poorly taught technicians. Positive over-the-counter (OTC) test results should always be confirmed by sending the sample on to a laboratory to be retested.
- Last use—The amount of time between the last use of a substance and a drug test affects detection because some drugs stay in the system longer than others. That said, someone who uses drugs may try and postpone a drug test.
- Medications and supplements—Prescription drugs, OTC medications, and, even, specific supplements could possibly interfere with test results.
- Individual metabolism—Factors such as age, weight, and overall health affect how quickly our body metabolizes the things we ingest.
False negative results
Urine tests have always been the most widely used type of drug test. However, even though it’s detectable now, the ability to tamper with the specimen is causing many employers to rethink using this test. Even the Department of Transportation is working toward incorporating the oral fluid and, eventually, hair drug tests to allow employers to switch their drug testing methods.
It’s virtually impossible to tamper with oral fluid and hair drug tests. The test subject is never out of sight of the test technician.
False negatives triggered by drinking a lot of fluid prior to the test are very hard to achieve today. That’s because laboratories now measure the creatinine in the urine. If the level is off, it’s because the sample is diluted. Specific gravity tests further determine if the specimen was adulterated.
Other adulterants used to try and cheat the urine test include:
- Using products that claim to remove or mask drug metabolites
- Drinking vinegar to alter the urine’s pH balance
- Adding salt, soap, or eye drops to the urine sample
It’s not an adulterant, but some would be cheaters smuggle in synthetic urine or substitute using their own urine with someone’s who doesn’t use drugs.
Food and false positive triggers
It’s true that consuming certain foods can still cause someone to test positive for drug use.
Those foods are:
- Poppy seeds—It would take a lot of them, especially since opiate test levels have been raised to a slightly higher level, but consuming poppy seeds prior to a drug test could cause a false positive result.
- Hemp seeds—THC remains in the body much longer than other drugs. Someone who uses pot every day can test positive for the drug for up to three months! It just makes sense that consuming hemp seeds would have the same effect. The level of THC accumulates within the body and could trigger a false positive.
- Coca tea—This tea is made from coca leaves. The same plant that is used to produce cocaine. Research has determined that coca tea breaks down releasing cocaine metabolites into the drink. Depending on the strength of the tea, someone who consumes this beverage could test positive for cocaine for up to 36 hours after drinking it.
- Pizza—Believe it or not, the yeast in pizza dough ferments sugars into alcohol. This could leave traces of alcohol in the mouth triggering a false positive breathalyzer result. It’s best to wait and grab that pie on your way home rather than prior to the test.
- Durian—This tropical fruit has a rich, custardy, yet complex flavor that they say you either love or hate. Nonetheless, durian lovers shouldn’t partake prior to a drug test because it could lead to a false positive if given a breathalyzer test for alcohol use.
- Mouthwash—Even though the levels of alcohol left in the mouth after using mouthwash drop quickly, it’s a good idea to freshen your breath with a mint or stick of gum before you head out the door for a drug test.
Easily avoidable
The odds are that should you love poppy or hemp seeds sprinkled on or throughout your food, you won’t reach the “test positive” level.
Moreover, risking a false positive on a drug test isn’t the end of the world should it happen. Most employers have made provisions for the chance of a false positive test result and the employee is allowed to retest once the circumstances—such as having ingested any of the above substances prior to the test—have been explained. Still, rather than going through the experience, it’s a good idea to refrain from partaking for a bit.
Changing up your diet won’t be the end of the world either, right? The end result is that it eliminates the risk that you’ll pop positive which some would find to be an embarrassing position to find themselves in.
Bon appetite.
