Are there any side effects from taking hair loss medication for a long time?

Lately, I have been increasingly concerned about my hair loss, so I am considering taking medication. I am wondering if there are side effects as well as benefits.

In particular, I would like to know if there are any burdens when taking it for a long period, and if symptoms such as heartburn, headaches, and fatigue actually occur frequently. I heard that the maintenance effect only lasts while taking the medication, so I am also curious if hair loss accelerates again once I stop taking it.