Causes of False Positive THC Urine Test

Certain tests can be performed with your blood or urine to know if you are using drugs. One of those is the THC urine test which will search for tetrahydrocannabinol (THC) – a metabolite of marijuana. A positive result will indicate a recent use of this drug. But sometimes, this test can give a false positive when you have never used marijuana. Why can this happen?

Causes of False Positive THC Urine Test

1. Methodology and Human Error

Since laboratory people are involved in the analysis process for THC in the urine, there is a chance of human error such as wrong labeling or external contamination. Also, the test used by most laboratories is EMIT (enzyme multiplied immunoassay technique) which can sometimes give a false positive result by recognizing other similar but not marijuana related THC metabolites in the urine.

2. Protonix

Protonix, also known by its generic name as pantoprazole, is a drug used in the treatment of gastroesophageal reflux disease (GERD) and Zollinger-Ellison disease, and can potentially give a false positive THC urine test. Since this drug is commonly used by many people, bringing all your prescriptions bottles with you to the laboratory is highly recommended.


NSAIDs or nonsteroidal anti-inflammatory drugs, are a group of medications known to provide relief for pain, fever and inflammation. Ibuprofen (Advil or Motrin), naproxen (Aleve), aspirin (Ascriptin or Ecotrin) and diclofenac (Cataflam or Zorvolex) are some of those. It is suggested to bring all your prescriptions bottles with you to the laboratory.

4. Dronabinol

Marinol, also known by its generic name as Dronabinol, is considered the medical marijuana since its main active component is synthetic THC, and this is why it will lead to a false positive result during a marijuana screening. Dronabinol is used in the treatment of nausea and vomiting during chemotherapy treatments.

5. Vitamin B Supplements

Some vitamin B supplements, especially riboflavin (vitamin B2) which can be found in some foods like cheese, mushrooms, spinach, oily fish, pork and almonds can lead to a false positive marijuana test. In the case of synthetically produced riboflavin, some manufactures use hemp seed oil during the process, which increases the chance of finding THC traces in the urine, thus giving a false positive THC urine test result.

7. Hemp Seeds

People who frequently consume products containing hemp seeds such as hemp seeds milk or hemp seeds oil are in higher risk of having a positive marijuana test result. Hemp seeds contain very small quantities of THC, and the test used for its screening cannot differentiate whether the patient has used marijuana or has just eaten hemp seeds.

It is important to note that hemp seeds are completely legal and many people consume them on a daily basis. Normally, this food must be taken in very large quantities and for prolonged periods of time to get a positive THC test result. Since THC is stored in body fat, it can still give a positive result up to a month after you have stopped eating hemp seeds or hemp seeds products.

8. Other Factors

Diabetes, kidney disease and liver disease can also cause a false positive marijuana urine test result. You need to inform the laboratory personal about any disease or health condition that you may be suffering and bring your prescription drug bottles with you for them to see in case of any future dispute.

What to Do If You Have a False Positive THC Urine Test

  • It cannot be stressed enough the importance of notifying the laboratory staff about your medical conditions, drugs or some of the listed above food consumption. Always bring your prescribed drug bottles with you and show them to the personal. This way, if the marijuana test comes back positive, you will have this precedent at your favor when asking for a second test.
  • Whether you had given this information before taking the test or not, you still can empathize your innocence when speaking with the authorities and request a new test different from the first one while explaining the reasons that lead to a false positive result. You should always defend yourself if a false accusation is made against you.
  • If the drug testing authorities allow you to take the second test, then you should prepare for it several days in advance: avoid all of the foods listed above; avoid potentially contaminated places; do exercises and drink at least two liters of water per day.
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