Short answer
Commercial and airline pilots need regular medical exams. The interval depends on the authority, medical class, age and type of operation.
Answer
Pilots need regular medical examinations to keep the medical certificate required for their licence and operation. The exact interval depends on the aviation authority, medical class, pilot age and type of flying.
Validity depends on the authority: For many EASA commercial and airline pilots, a Class 1 medical certificate is normally valid for 12 months. It is reduced to 6 months for pilots who have reached age 60, and also for some single-pilot commercial passenger operations after age 40.
Under the FAA system, first-class medical privileges for airline transport pilot operations are generally valid for 12 months if the pilot was under 40 at the examination, and 6 months if the pilot was 40 or older. The certificate may still carry lower-class privileges after the first-class privilege period ends, depending on the pilot and operation.
Medical validity can be shorter if the authority or medical examiner adds a limitation or asks for follow-up checks. Pilots should track expiry dates carefully, because flying with an expired or invalid medical certificate can make them unfit for duty and create licensing problems.
The exam is not only a quick eyesight check. Depending on age and authority, it can include blood pressure, urine test, vision, hearing, cardiovascular review, medication review and questions about mental health or recent illness.
Pilots should book renewals early enough to solve paperwork or specialist-report issues before expiry. A medical that is valid today can still become unusable if a new illness, injury or medication makes the pilot temporarily unfit.
Next step: Check the Pilot Requirements Guide before spending serious money on training.