As you may be aware from the FAA’s safety outreach on this topic, impairment from medication, particularly over-the-counter (OTC) medication, has been cited in a number of general aviation (GA) accidents. An FAA study in 2011 found both illicit drugs and medications in 570 (42%) of the 1,353 pilots tested from fatal accidents. Of the pilots with positive drug results, 90% were flying under 14 CFR part 91.
The problem lies with the fact that both medical conditions and drugs (legal and illicit) can compromise a pilot’s ability to control the aircraft and/or adversely affect judgment and decision making. Among OTC medications, the most common potentially impairing medications are antihistamines. These medications are used for allergies, colds, and even as sleep aids. All of these medications have a warning on the label that states “may cause drowsiness” or advises the user to “be careful when driving a motor vehicle or operating machinery.” According to an NTSB study, sedating antihistamines are the most commonly detected medication in fatal accidents. Most “nighttime” or “PM” medications contain a sedating antihistamine, such as diphenhydramine or doxylamine. Diphenhydramine (best known as Benadryl®) is also an active ingredient found in many medications like Tylenol® PM. Nyquil™ contains doxylamine. It’s essential to know the sedating effects of these medications, especially if you are taking them to treat some other condition.
Many pilots are unaware that there are wait times after each use of sedating antihistamines. For cetirizine (Zyrtec®) and levocetirizine (Xyzal®), you should not fly for 48 hours after taking the last dose. For diphenhydramine or doxylamine, you should not fly for 60 hours after taking the last dose. For chlorpheniramine (found in Chlor-Trimeton) and clemastine (found in Tavist or Dayhist), you’ll have a longer wait time of five days after the last dose. If you suffer from allergies, consider a non-sedating antihistamine instead, such as loratadine (Claritin®) or fexofenadine (Allegra). Claritin and Allegra do not have wait times (after the initial ground trial). See bit.ly/AllergyAntihistamine for more.
Some drugs can also cause sedation as well as cognitive impairment. These include loperamide (an antidiarrheal medication) or dextromethorphan (a cough suppressant). Frequently, there are alternative options that are not impairing and are acceptable to the FAA (assuming that the underlying condition is safe for flying). We suggest you work with both your primary care doctor and your AME before considering the use of these and other medications.
While your primary care doctor should know your personal health history, an AME has training in the impact of different conditions on aviation safety and in which medications are permissible in the aviation environment.
Supplements are another area of concern as they may also interact with OTC and prescription medications to cause impairment. It’s important to note that even though supplements may have labels similar to OTC medications, they are not regulated by the FDA. Accordingly, they do not need to meet a specific standard. This is especially concerning for cannabidiol (CBD) products. The CBD industry has widely varying quality control and labeling, leading to significant discrepancies from package labels, including much higher levels of tetrahydrocannabinol (THC) — the component that gets one “high” — than disclosed. This can cause both impairment and possibly a positive drug test. If a drug test is positive due to CBD, it is considered and acted upon as a true positive test and can have legal ramifications. Therefore, the FAA strongly discourages the use of CBD products by airmen.
Still unsure about what medications are safe to use when flying? Then check out the OTC medication guide at faa.gov/go/pilotmeds. This guide provides pilots with a list of commonly used OTC medications that are generally safe (GO) and those that are not (NO-GO). Even for medications acceptable for flying, you should always perform a ground trial of 48 hours after starting a new medication. Take a close look at the OTC guide because some medications pilots regard as equivalent may have very different impacts on safety. You should also review the “Do Not Issue/Do Not Fly” section of the AME Guide: bit.ly/NoIssueOrFly. Keep in mind that the lists of medications in this section are not meant to be all-inclusive or comprehensive but rather address the most common concerns.