According to the latest edition of the Federal Air Surgeon’s Medical Bulletin, the FAA has revised the dosing interval standard (the time between taking medicine with known side effects until going flying) to reflect a longer waiting time. The standard has been increased from two to five dosing intervals. For example, if the instructions on the medication bottle say to take every six hours, then an airman must wait until at least 30 hours after the last dose before he or she may fly. The FAA also advises that an airman should “[n]ever fly after taking a new medication for the first time until at least five maximal dosing intervals have passed and no side effects are noted.”
It is important to note that this dosing interval standard only applies to certain disqualifying medications such as antihistamines (e.g. Benadryl or Zyrtec). If an airman is taking other disqualifying medications (e.g. antiepileptics, antispasmodics, and certain alpha blockers and antihypertensives) he or she will need to obtain FAA approval for return to flight after discontinuing the medication. More information on this topic is also available in the Guide for Aviation Medical Examiners
