I can provide you with some information that may be helpful.
Finasteride is a prescription medication that is used to treat male pattern baldness. It works by blocking the conversion of testosterone to dihydrotestosterone (DHT), which is thought to be a major cause of hair loss in men. The recommended dose for treating hair loss is 1 mg per day.
According to the European Aviation Safety Agency (EASA), pilots who are taking medication for medical conditions must obtain approval from an authorized medical examiner (AME) before flying. The AME will assess the pilot's fitness to fly based on the medical condition and the medication being taken. In the case of Finasteride, it is important to note that it is classified as a prohibited substance by the World Anti-Doping Agency (WADA) when used to enhance performance.
If you are considering taking Finasteride and you are a commercial pilot with an EASA license and medical certification, you should consult with an AME to determine whether the medication is approved for use in your specific situation. The AME will be able to provide you with guidance on the medical certification process and any restrictions that may apply to your flying activities.
It is also important to note that hair loss can have many causes, and there may be other treatments or lifestyle changes that could help. You may want to discuss your concerns with your personal physician or a dermatologist who specializes in hair loss.