For aviation safety, airmen should not fly following the last dose of any of the medications below until a period of time has elapsed equal to:
5-times the maximum pharmacologic half-life of the medication; or
5-times the maximum hour dose interval if pharmacologic half-life information is not available. For example, there is a 30-hour wait time for a medication that is taken every 4 to 6 hours (5 times 6)
Label warnings. Airmen should not fly while using any medication, prescription or OTC, that carries a label precaution or warning that it may cause drowsiness or advises the user "be careful when driving a motor vehicle or operating machinery." This applies even if label states "until you know how the medication affects you" and even if the airman has used the medication before with no apparent adverse effect. Such medications can cause impairment even when the airman feels alert and unimpaired (see "unaware of impair" above).
Allergy medications.
Sedating Antihistamines. These are found in many allergy and other types of medications and may NOT be used for flight. This applies to both nasal and oral formulations.
Nonsedating antihistamines. Medications such as loratadine, desloratadine, and fexofenadine may be used while flying, if symptoms are controlled without adverse side effects after an adequate initial trial period.
Muscle relaxants: This includes but is not limited to carisoprodol (Soma) and cyclobenzaprine (Flexeril).
Over-the-counter active dietary supplements such as Kava-Kava and Valerian.
Pain medication:
Narcotic pain relievers. This includes but is not limited to morphine, codeine, oxycodone (Percodan; Oxycontin), and hydrocodone (Vicodin, etc.).
Non-narcotic pain relievers such as tramadol (Ultram).
"Pre-medication" or "pre-procedure" drugs. This includes all drugs used as an aid to outpatient surgical or dental procedures.
Sleep aids. All the currently available sleep aids, both prescription and over-the-counter (OTC), can cause impairment of mental processes and reaction times, even when the individual feels fully awake.
See wait times for currently available prescription sleep aids
Diphenhydramine (Benadryl) - Many OTC sleep aids contain diphenhydramine as the active ingredient. The wait time after diphenhydramine is 60 hours (based on maximum pharmacologic half-life)