It's the mini pill, right?
If he is pre-T, it is probably a good option, though there are a lot of side effects that you should look at and be aware of. Hormone blockers would also help curb his period and may be a better fit depending on his age and how deep into puberty he is.
If he is on T or will be getting on T soon, ask about depo provera shots. They are used to stop periods and they don't mess with hormone levels.