08-05-2019 Drugs

10 medications that trigger false positives on drug tests

Some medications may cause false positives on drug tests.

The America’s Pharmacy website recently received this question from a customer: 

“I need to do a drug test to get hired by my new employer. Are there any legal drugs that might cause a ‘false positive’ on a standard drug test?”
- Wesley R.

We realize this is an important concern for a lot of Americans. Many employers require that their employees submit a urine drug screen test. These tests look for the presence of specific illegal drugs and prescription medications in the body of the person being tested.

From time to time we hear about people claiming that they failed a drug test because of a false positive, but incorrect results of drug tests can actually happen. Below are 10 common prescriptions and over-the-counter medications that you’ll want to consider. And of course, before taking (or changing) any prescriptions, please consult with your physician.

1. Dextromethorphan (Robitussin, Delsym)

This medication is used for temporary relief of coughs without phlegm that are caused by certain infections of the air passages (e.g., sinusitis, common cold). It is a cough suppressant that works by decreasing the feeling of needing to cough Dextromethorphan is an active ingredient in Robitussin, Delsym, and additional cough suppressants that can be purchased over the counter. Dextromethorphan might trigger a false positive in tests screening for opiates and PCP (phencyclidine).

2. Diphenhydramine (Benadryl)

Diphenhydramine is an antihistamine used to relieve symptoms of allergy, hay fever, and the common cold. It is a common ingredient over-the-counter allergy-relief and sleep-aid products. It is also used to prevent and treat nausea, vomiting and dizziness caused by motion sickness. Diphenhydramine can also be used to help you relax and fall asleep. This medication works by blocking a certain natural substance (histamine) that your body makes during an allergic reaction. Its drying effects on such symptoms as watery eyes and runny nose are caused by blocking another natural substance made by your body (acetylcholine). Taking diphenhydramine could trigger a positive test result for methadone or PCP

3. Metformin (Glucophage)

Metformin is used with a proper diet and exercise program and possibly with other medications to control high blood sugar. It is used in patients with type 2 diabetes. However, metformin can also trigger a positive test for amphetamine or methamphetamine in a drug screening.

4. Fluoxetine (Prozac)

Fluoxetine is used to treat depression, panic attacks, obsessive compulsive disorder, a certain eating disorder (bulimia), and a severe form of premenstrual syndrome (premenstrual dysphoric disorder). Taking Fluoxetine might trigger a false positive in drug screenings for amphetamine, methamphetamine or LSD.

5. Amitriptyline (Amitril)

Amitriptyline is used to treat mental/mood problems such as depression. It may help improve mood and feelings of well-being, relieve anxiety and tension, help you sleep better, and increase your energy level. This medication belongs to a class of medications called tricyclic antidepressants. It works by affecting the balance of certain natural chemicals (neurotransmitters such as serotonin) in the brain.

Amitriptyline might trigger a false positive on a urine test that is testing for the hallucinogenic drug LSD (lysergic acid diethylamide).

6. Sertraline (Zoloft)

Sertraline is used to treat depression, panic attacks, obsessive compulsive disorder, post-traumatic stress disorder, social anxiety disorder (social phobia), and a severe form of premenstrual syndrome (premenstrual dysphoric disorder). But if you’re taking it, you might trigger a positive result for tests for benzodiazepines or LSD.

7. Diltiazem (Cardizem)

Diltiazem is used to treat high blood pressure (hypertension) and prevent chest pain (angina). Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems. When used regularly, diltiazem can decrease the number and severity of episodes of chest pain from angina. It may help increase your ability to exercise. Diltiazem is called a calcium channel blocker. It works by relaxing blood vessels in the body and heart so blood can flow more easily. Diltiazem also lowers your heart rate. These effects help the heart work less hard and lower blood pressure. But if you are taking diltiazem, a urine drug screen test may trigger a false positive for LSD.

8. Bupropion (Wellbutrin)

This medication is used to treat depression. It may also be used to prevent seasonal affective disorder (SAD), a type of depression that occurs each year at the same time (for example, during winter). This medication can improve your mood and feelings of well-being. It may work by restoring the balance of certain natural substances (dopamine, norepinephrine) in the brain. But be aware that it is possible that this drug might trigger a false positive in tests screening for amphetamine, methamphetamine or LSD.

9. Labetalol (Trandate)

Labetalol is used with or without other medications to treat high blood pressure (hypertension). This medication is both an alpha blocker and beta blocker. It works by blocking the action of certain natural chemicals in your body such as epinephrine on the heart and blood vessels. This effect lowers the heart rate, blood pressure, and strain on the heart. But you’re taking labetalol, it could trigger a false positive in tests for amphetamine, methamphetamine or LSD.

10. Methylphenidate (Ritalin)

This medication is used to treat attention deficit hyperactivity disorder - ADHD. It works by changing the amounts of certain natural substances in the brain. Methylphenidate can help increase your ability to pay attention, stay focused on an activity, and control behavior problems. It may also help you to organize your tasks and improve listening skills. But it can also trigger a false positive when testing for amphetamine, methamphetamine and LSD.