I use finasteride for this exact reason.
I considered minoxidil as well but it just seems too awkward in some ways (I have never used it, but I believe it gives you white flakes and a greasy texture).
I'm pretty sure the finasteride has thickened my remaining hair up, stopped it and even my norwood area hair (main scalp etc) has stronger hair now (not enough, but you get my point).
People always say that the horshoe is pretty safe, but it's just really not true. too many people have serious issues over time.