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Can Coffee Cause a False Positive Drug Test? What You Need to Know

person holding a positive drug test

If you have a drug test scheduled, you may have heard that you shouldn’t drink caffeine before the test. Many people want to know if coffee can cause a false positive drug test. The short answer is that it depends on what the test is looking for, but sometimes coffee can trigger it. Keep reading as we discuss what drugs might be mistaken for caffeine and why you shouldn’t drink coffee before a test.

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Can Coffee Cause a False Positive Drug Test?

In the past, drug tests were much less sensitive than they are today, and it was more common to get a false positive by eating certain foods like poppy seeds or drinking a beverage like coffee or an energy drink. Caffeine, in particular, could lead to a false positive on a drug test for methamphetamines. However, modern testing has come a long way, and there are not nearly as many false positives now as there were in the 1970s. These tests also look for a wide range of drugs at the same time, which was impossible 40 or 50 years ago. Therefore, it’s unlikely that coffee will trigger a false positive on most standardized tests.

urine drug testing
Image Credit: Lothar Drechsel, Shutterstock

Will Caffeine Trigger a False Positive on a Drug Test?

If you get your caffeine from coffee, the answer is no. However, if you consume caffeine in energy drinks, there is some concern that it can produce a false positive on a BAC (alcohol breathalyzer test). Some brands use a small amount of ethanol that won’t get you drunk but might still raise the flag. The Rockstar Juiced Energy Drink, for example, contains glycerol ester of wood rosin, which might trigger a false positive in some tests.

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What Foods Will Trigger a False Positive?

Poppy Seeds

Drug tests are becoming more accurate and complex, which helps minimize the number of false positives. However, some foods might still trigger them if you consume too much in one sitting. For example, poppy seeds are used to trigger false positives. While the modern tests won’t get fooled by the number of poppy seeds in an average meal, consuming a large amount (more than 3 teaspoons) in a single sitting might still trigger a false reading.


Mouthwash is a product that often contains alcohol, and while it might not trigger a false positive at your work drug screening, it has the possibility of setting off a flag during a BAC. If you need to take these tests frequently, it’s best to choose an alcohol-free brand.

two bottles of listerine mouthwash
Image Credit: Olichel, Pixabay


Some antibiotics can trigger a false positive on a drug test, including Rifampin, which doctors use to treat tuberculosis. However, you can usually explain your need for antibiotics to the physician running the test to ensure that there are no complications.


If you’re a sufferer of seasonal allergies and take antihistamines for relief, you risk triggering a false positive on your test. One of the biggest problems is the ingredient diphenhydramine, which can be found in several over-the-counter medications, including Benadryl. It tends to cause a false positive for the hallucinogenic drug PCP.

Cold Medicine and Sleep Aids

Many over-the-counter cold medicines help reduce congestion, which can produce a false positive for methamphetamines, and the sleeping aids that are in this medicine and sleeping tablets can cause a false positive for PCP or methadone.

Commercial Medication

You might need to take several other medications that can trigger a false positive on a drug test, and you will need to alert your physician to them before they run the test. Some HIV medications, like Efavirenz or Sustiva, can trigger a false positive, as can proton pump inhibitors that reduce the amount of stomach acid. Popular brands of pump inhibitors include Prilosec and Nexium, and these drugs can produce a false positive for THC, the substance found in marijuana.

variety of medicines
Image Credit: Pexels, Pixabay

Why Shouldn’t I Drink Coffee Before My Drug Test?

People suggest that you shouldn’t drink coffee before a test because most tests take place in the morning, when people like to have their morning cup, and drinking too much liquid before a test can dilute your urine. If the urine is too diluted, it will usually trigger a false positive in response to them not being able to test it. Doctors look for other items commonly found in urine, like creatine, when running the tests, and they know how much the average person has per unit. If there are too few, they will know that the urine is diluted. They may believe that you are trying to manipulate the test, since it was common in years past to drink enough water that any drugs weren’t detectable.

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Fortunately, coffee is extremely unlikely to trigger any false positives in a drug test, or most people would be in trouble. While it would trigger a false positive for methamphetamines years ago, drug tests have advanced enough to tell the difference. Still, it would be best if you didn’t drink coffee before a test in order to avoid diluting your urine. This way, the doctors will have a good sample to examine. In fact, many places will request that you don’t drink anything before the test.

Featured Image Credit: Sasapin Kanka, Shutterstock


Ed Malaker

Ed Malaker, a veteran writer, has contributed to a wide range of blogs that cover tools, pets, guitars, fitness, and computer programming, and of course, coffee. He drinks a lot of it when he writes, making him an expert indeed. When he’s not writing, Ed is usually performing DIY projects around the house or working in the garden. He’s also a musician and spends a lot of time helping people fix their guitars and composing music for independent films.

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