Home » When OTC Drugs and Flying Don’t Mix

When OTC Drugs and Flying Don’t Mix

Posted By Benjamin Peterson

Published May 20, 2021

It’s getting toward the end of a long day and you’re getting ready to go flying. You know this is the time to be at your best—bright-eyed and bushy-tailed, as the saying goes. But maybe your allergies are catching up to you and your eyes are feeling tired and itchy. You reach for a Benedryl or its generic equivalent to clear up your allergies. Or you’re feeling a bit rundown so you reach for an energy drink.

It’s no big deal, right? It’s not like these are drugs on the FAA’s no fly list…They’re harmless over-the-counter (OTC) remedies.

And you wouldn’t take something like a sleep aid or anything that could cause heart palpitations or difficulty concentrating just before you go fly, right?

 But as a recent NTSB study found that by 2012 up to 40 percent of fatally-injured pilots had at least one positive drug finding (whereas in 1990 the number was only 10 percent), pilots need to be careful that they are not inadvertently impairing themselves with “remedies” when they need to be at their sharpest.

Sedating Antihistamines:  Benadryl vs ZzzQuil

When your body confronts an allergen, it releases a substance called histamine that binds to receptors on certain cells. This can cause congestion, runny nose, sneezing, hives, skin rashes, and itchy or watery eyes—reactions designed to help rid the body of the allergen, but also very inconvenient to someone trying to get work done. So you take an antihistamine to counteract the effect of the histamine being released.

There are several types of antihistamines on the market. The problem is that drowsiness is a side effect for many of the main ingredients used in antihistamines, especially “first generation antihistamines” using diphenhydramine or chlorpheniramine. Just how drowsy is drowsy?

Consider this: the main ingredient in allergy medication Benadryl is 25 mg of diphenhydramine HCL per tablet. The main ingredient in common sleep aid ZzzQuil—with labeling that shouts, “Fall asleep FAST!”— is… 25 mg of diphenhydramine HCL. Does that sound like something you want to take just before you start flying?

One of the reasons that ZzzQuil enables you to “fall asleep fast” is that it often combines the 25 mg of D-HCL with up to 10 percent alcohol to increase the drowsy effect. And some versions of ZzzQuil actually have 50 mg of D-HCL along with alcohol to really knock you out. So taking Benadryl may not be exactly the same as taking a dose of ZzzQuil, except that a dose of Benadryl could be one or two tablets, and when each tablet has 25 mg of D-HCL, now you’re back up to the 50 mg of D-HCL at max dosage. And Benadryl says you can take one to two tablets every four to six hours. ZzzQuil expects you to take one dose and you’re out.

So if you’ve been taking two tablets of D-HCL every few hours all day, and then get into an airplane—especially a propeller plane where the drone of the engine tends to make pilots drowsy already—chances are you’re not at your sharpest.

Remember that toxicology study mentioned in the opening paragraph? The study found 10 percent of the fatally-injured pilots had sedating antihistamines in their system, and seven percent specifically had diphenhydramine.

We’re not picking on Benadryl here; there are plenty of OTC medications with diphenhydramine or equally drowsiness-producing chlorpheniramine that pilots should stay away from if they are planning to fly soon. Just check labels. Some newer antihistamines with other ingredients such as cetirizine and loratadine are generally associated with less drowsiness, but can still make you drowsy.

Hopped Up on Energy Drinks

On the other side of the spectrum are those products designed to keep you awake, including the entire gamut of energy drinks from the concentrated “shots” to the oversized 32-ounce cans. Unregulated by the Food and Drug Administration (FDA), the energy drink industry has boomed over the past 20 years as both teens and working adults seek ways to stay awake during their long and busy days.

Again, not on the FAA’s no-fly list, energy drinks may be just as routinely consumed by pilots as by other people looking for a boost of energy. But have you thought about how most energy drinks do what they do, that is, how they deliver an extra shot of energy and how long it lasts?

There are dozens of energy drinks on the market because there are many ways to rev up the human condition. However, there are some commonalities: high amounts of sugar, caffeine, and other “boosting” ingredients. For example, energy drinks contain an average of 14 teaspoons of sugar in each serving, and many cans and bottles contain more than one serving. Ever experience a sugar crash and the tiredness that follows?

And then there’s the caffeine, which ranges between 70 and 294 milligrams per serving in most energy drinks (an 8oz cup of coffee averages 95 mg). Caffeine acts as a stimulant on the central nervous system, increasing your heart rate. Depending on your heart health, this can lead to heart palpitations and chest pain—certainly not anything you want to be experiencing while in the air.

If you’re already a heavy caffeine consumer, the effect of one energy drink isn’t going to be drastically noticeable, either on the positive or negative. However, if you rarely drink caffeinated beverages, and you decide to down an energy drink just before a flight, be prepared for the side effects: rapid heartbeat, headache, perhaps dizziness and nausea. The good thing is that these effects generally go away about five to nine hours later as the caffeine excretes from the body. But if you’re flying during these hours, it could be an uncomfortable ride.

Lastly, since energy drinks are unregulated by the FDA, manufacturers can add literally anything to the mix: vitamins B2/B6/B12, niacinamide, D-glucuronolactone, guarana, taurine, inositol, calcium pantothenate, l-valine, etc. Side effects of some of these ingredients or ingredient mixes can include difficulty concentrating, anxiety, weakness, tremors, seizure, and sleep disturbances.


As pilots, we need to be aware of the effect that OTC medications and energy drinks can have on our bodies while we’re in the air. While solving one problem, they may induce a host of other problems may become a factor if we’re called upon to execute emergency procedures and judgment.

Benjamin Peterson

Graduated from the University of North Dakota with a degree in Commercial Aviation as a Pilot and Flight Instructor. My first professional job was working for Cirrus Aircraft as an instructor.

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