Use for medical certification and aviation-related physiological and psychological factors; use [medevac] for medical evacuation aircraft and their procedures.
Aviation medicine covers many different aspects of health and human performance. There are two broad areas that are suitable topics for questions on this site: medical certification and general physiological or psychological considerations in aviation.
Pilots usually require a medical certificate in order to fly legally, although there may be exceptions for some light aircraft. The purpose of pilot medical certification is to confirm that the pilot has a basic level of physical ability needed for flying (eyesight, hearing, balance), and to ensure that there are no chronic (long-term) conditions that might cause sudden or temporary incapacitation during flight (e.g. heart disease, epilepsy, some medications).
Many countries have different levels or classes of medical certification, with higher levels being required for airline pilots and lower levels for private pilots. In some countries pilots may fly without an aviation medical certificate in certain conditions or aircraft types, such as the sport pilot certification in the US. All pilots are expected to use their own judgement and not fly if they feel unwell or unable to fly.
Apart from the actual certification process, there are many physiological and psychological issues that can affect pilots. Even a perfectly healthy pilot may experience visual illusions or false sensations of movement during flight (especially instrument flight) or suffer - perhaps unknowingly - from the effects of hypoxia in an unpressurized aircraft at a higher altitude. Night vision is also affected significantly by lack of oxygen. Stress, tiredness or medications can affect reaction times, decision making and judgement.
This tag can be used for any questions about aviation medical certification, general medical issues and physical or psychological issues, if they relate directly to aviation.