False Positive Drug Test: Blame Your Food and Medications

False Positive Drug Test Why Does It Happen
Strangely enough, common food items or medications might be the reason you had a false positive drug test. Discover in detail about who are the real culprits.

Firstly, a false positive drug test can be a devastating news for you, your family members and friends. Furthermore, It can take its toll on your professional and social life as well. Therefore, learning about its causes will help you take necessary precautions before you finally go for a drug test.

You may need to have drug abuse tests at your college, workplace or to fulfill certain legal requirements. Usually, these tests analyze the urine sample. However, the doctor may ask for other specimens like saliva, hair or blood.

Drug abuse tests detect the presence of amphetamines, cannabinoids, cocaine, heroin and phencyclidine in the specimens. Regrettably, no drug test can have 100% accuracy. As a result, you might end up having a positive result for drugs you did not take.

In addition, a number of food items and some prescription or OTC medicines can also turn the test results against you.

What is A False Positive Drug Test?

A false positive drug test means you get a positive result for the drug but in reality, you didn’t take it.

You might be wondering how it is possible for to test positive if you haven’t taken any drugs.

However, it’s quite possible. And studies suggest false positive test results occur in 5 to 10% of the total cases.

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How Does False Positive Drug Test Occur?

Drug Test

False positives occur when the analytical drug detection method recognizes some of the molecules in your body as drugs. Due to some errors in the analysis, it fails to differentiate between the drug molecule and other structurally similar molecules. Consequently, after a positive test, you will need other tests to confirm abuse of the drug.

A drug test commonly involves the use of Enzyme-mediated Immunoassay (EIA). Because this test offers the privilege of mass screenings, quick results and low cost. As a result, most doctors prefer EIA. However, this test is not error-free and can lead to false positive results.

EIA uses a complex of enzymes and antigens. In addition, the test results depend on whether the drug or the antigen binds to the antibody present in the body.

Even if you have a very small quantity of the drug in the body, it binds to the antibody leaving the enzyme free. Next, the free enzyme produces certain signals which are detected by an instrument called spectrometer.

If there are no drugs, the antigen binds to the antibody in the enzyme-antigen complex thus limiting the activity of the enzyme. Consequently, the limited enzyme activity means the spectrometer cannot measure the signals.

Firstly, false positive drug test can occur due to a mismatch between the antibody and the substance. This could be chemically related to the drug or its metabolites. Sometimes, you might eat something without realizing that they contain trace amounts of the drug or related substances. For example, bagels, rolls, and pastries contain certain amounts of poppy seeds that may give a false positive result for morphine.

In any case, when EIA shows positive, you’ll need to confirm it using a more advanced technique called GC-MS. (Gas chromatography Mass Spectroscopy)

What Can Cause A False Positive Drug Test

incidentally, certain medications, both prescription and OTC, can cause a false positive drug test. It is because many of the constituents in these medications might be chemically similar to the drugs being tested.

Here are some medications which might give a false positive result

  • Quinolones: Antibiotics such as ofloxacin, gatifloxacin, and ciprofloxacin can give positive test results for opiates and phencyclidine.
  • Rifampin: This first line antitubercular medication might be the cause for the positive opiate test.
  • Verapamil: Verapamil is an antihypertensive medication that may cause positive methadone test in some cases.
  • Diphenhydramine: Antiallergic medication diphenhydramine may trigger positive results for methadone, opiates, and phencyclidine.
  • Antidepressants: Sertraline may show positive results for diazepam.
  • Analgesics: These include common OTC pain medications like ibuprofen and naproxen.
  • Certain OTC products such as anti-cold tablets that contain pseudoephedrine could be the reason why you tested positive for amphetamines.

Note: This list does not contain all the medications that might cause a false positive drug test. Therefore, it’s important you tell your doctor about all the drugs (prescription or OTC), supplements, and food items.

Factors That may Cause False Positive Drug Test

  • When did you have the test
  • If there are metabolic products of the actual drug in the body
  • Sensitivity of the detection technique

The Bottomline

In conclusion, a false positive drug test does not mean you abuse drugs. It means you need to recheck your diet or medication. In any case, if the test is positive, the patient should consult the doctor and take another test to confirm.

You can learn more about the false positive drug test, drug addiction or aspects of drug abuse or other tests. First, talk to the experts near you or click here for more details.

False Positive Drug Test: Blame Your Food and Medications

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Comments 2

  • I have a question maybe someone can direct me where and what to do. I am on some heavy pain meds due to two horrific neck surgeries for the past 15 years. During that 15 years I was drug tested regulary with urine drug test where there was never a problem. On Wednesday September 5th my pain clinic Dr in pa did the first oral drug test I have ever done in my 60 years of life. 5 days later they call me telling me that they are discharging me because my oral drug test tested positive for cocain and suboxone, I dropped the phone because I have never done these drugs in my life .. Plus he put this false positive in my records and now no Dr will see me. In my.neck there is 3 inches of bone from my left leg, two inches of hip bone, two 10 inch bolts and 16 screws I have 5 days of medication left im lost !!!!

    • Primary care may help but most say go to pain clinic. Won’t the place that discharged you do another test. Yesterday I was at probation and they drug tested me and alcohol tested me and alcohol came back with a faint line. I passed however my probation officer is suspicious. The last drug test before that had a faint line for subsoxone. I passed however I’m afraid every time they will violate me due to these tests. I’m in a lot of pain due to a car accident and on disability and no one will give me pain mess unless I have surgery. I was discharged from a subsoxone clinic a few years ago due to a positive test. They should know these tests aren’t a 100% accurate. They drug tested me in hospital and came back positive for pop which I’ve never touched. We did research and I was on a anti depressant called Effexor which caused the positive reading for pop. I know what your going through if that any consultation. I hope something happens for you. I know it’s a tough spot. Don’t know if I was any help.

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