Impairment from medication, particularly over the counter (OTC) medication, has been cited in a number of accidents in general aviation.
A 2011 study from the FAA’s Civil Aerospace Medical Institute (CAMI) Toxicology Lab found drugs and medications in 570 pilots from 1,353 total fatal pilots tested. That’s 42% of the pilots who died in accidents.
Most of the pilots with positive drug results, 511 — or 90% — were flying under CFR Part 91.
Some of the most common, potentially impairing medications are antihistamines. These allergy medications can have powerful sedating effects, so much so that the primary offender, diphenhydramine (known by most as Benadryl), is often used as an OTC sedative and is the sedating agent in most PM pain meds.
According to an NTSB study, sedating antihistamines are the most commonly detected medication in fatal accidents.
Cardiovascular drugs are also commonly present in fatal accidents. The majority of medications used to treat high blood pressure are safe to use while flying. For other cardiac conditions, it is important that you check with your AME to ensure that you are not using an unsafe (and prohibited) medication.
Some less common impairing drugs include antidiarrheal drugs (some contain opioids), anti-seizure drugs, some smoking cessation drugs, and some antidepressants.
For many of these drugs, there are options that are not impairing or disqualifying if you work with your primary care doctor or AME. If you suffer from allergies, you might use loratadine instead of diphenhydramine, for example.
What to Look For
The Food and Drug Administration (FDA) requires standard labeling for all OTC medications. These standard labels indicate the active ingredients, directions for use, and highlight potential side effects like drowsiness.
Still confused? The FAA has released a new OTC medication guide, which you can download here.
The guide provides pilots with a list of medications that are generally safe when used to treat a common ailment (GO) and those that are not (NO-GO).
It also includes a Do Not Issue/Do Not Fly section.
You can also find good information on drugs through trusted government sites like the National Institute of Health’s Medline site at MedlinePlus.gov. This site lists both generic and trade names along with side effects and warnings for almost every drug out there.
How long should you wait after taking one of these medications?
If you have to take a disqualifying or impairing medicine, how long should you wait before resuming flying?
Every medicine is different, but a good rule of thumb is five times the half life of the medication. The easy way to determine this is through the dosing interval. If a medication says to take it four times a day, the dosing interval would be six hours. That means the wait time after the last dose would be 30 hours (6 hours x 5 = 30 hours).
Other medications may have longer or shorter intervals which is why it’s important to talk to your AME, FAA officials advise.