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Allergies and Allergy Medication

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By FAA Medical Specialties Division Staff

The spring months bring welcome warmth but also an unwanted stowaway — seasonal allergies. In terms of fitness for flight, allergies usually fall into the category of a condition that pilots can manage without assistance from an Aviation Medical Examiner (AME) or other physician.

Remember, though, that the swollen, boggy, nasal and sinus tissues associated with allergies are a prime setup for ear and sinus blocks, which can be incapacitating. And just because you can safely ascend does not mean you can safely descend. The swelling seen in both allergies and “colds” can turn some air passageways into one-way valves — expanding air can escape, but one cannot “repressurize” on descent. If the symptoms are bad enough to interfere with your ability to act as pilot in command, then you should ground yourself until the symptoms have subsided.

It’s similar, but not identical, to dealing with fatigue. If you feel fatigued, you should ground yourself until you can get sufficient rest. Once rested, no medical clearance is required to return to flight status.

So what’s different with allergies? Some of the most common over-the-counter (OTC) medications used to treat them can be more problematic than the allergies themselves. The chief offender is diphenhydramine (common trade name: Benadryl®). It is one of the most prevalent and commonly used medications, both alone and in combination products, and its prevalence can create a problem. Since diphenhydramine is an OTC medication and widely available, it doesn’t occur to most pilots that it might be disqualifying. But it is.

Frequently Asked Questions

Q: What is the concern with diphenhydramine?

Diphenhydramine is a sedating antihistamine. In fact, it is such an effective sedative that it is used in most OTC combination pain relief medications (i.e., Tylenol PM®) intended for bedtime use, and it is the sole active ingredient (i.e., Zzzquil®) in most OTC sleep aids. Even if diphenhydramine doesn’t put you to sleep, it can dramatically impair your cognitive abilities, which are critical to your safety.

Q: Is diphenhydramine (Benadryl) the only concerning sedating allergy medication?

No, there are others, such as chlorpheniramine (Coricidin®) and doxylamine (found in Vicks NyQuil®). If the box warning says “May cause drowsiness” or if it advises the user to “be careful when driving a motor vehicle or operating machinery,” then the medication is NOT safe for flying.

Q: Are there allergy medications that I can take and still fly?

Yes, there are a number of non-sedating antihistamines available. These include loratadine (Claritin®), desloratadine (Clarinex®), and fexofenadine (Allegra®). If one of these medications controls your symptoms without making you sleepy, you may use them and continue flying with no wait time if you have no adverse effects during an initial 48-hour ground trial for any new medication.

Q: What if I have to take diphenhydramine?

For some aviators, diphenhydramine may be the most or only effective solution. In that case, you should be aware that laboratory testing has demonstrated an extremely long period of impairment associated with diphenhydramine. This is why you should wait five times the maximum pharmacologic half-life (or 60 hours) before returning to flight.

Resources

One of your best resources is the Allergy — Antihistamine & Immunotherapy Medication page in the AME Guide: bit.ly/30LJsF1 (PDF download). It describes in detail what medications are allowed, require a wait time, or are unacceptable.

Additional Resources

If you have any questions, don’t hesitate to contact an AME or your Regional Flight Surgeon’s (RFS) office.

This article was originally published in the May/June 2022 issue of FAA Safety Briefing magazine. https://www.faa.gov/newsroom/faa-safety-briefing-magazine
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