Make sure to read up on the negatives before considering it:
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Quite a few medical documents I've seen seem to be very conclusive about it permanently lowering libido/causing erectile dysfunction. As with any drug, there's a chance you won't experience these side effects. But then again, what's the use of pretty hair without a functioning dick?
Consider that finasteride is primarily used to treat MPB. Typically that tends to encompass those who are naturally balding, and especially those who are genetically predisposed to it. You say you had "a bit of hairloss"...are you sure you want to take the risks of finasteride to prevent that? Did the hair never grow back? Hairloss on cycle is not a sign of balding, often times it's a sign of strong adrogenic activity, those who are not predisposed to balding often lose hair and then grow it back after they're off cycle. Are you worried about gear causing permanent baldness (meaning you're predisposed to it, ie it's going to happen eventually whether you're on gear or not), or just about shedding?
If it's the former, talk to your doctor about long-term use of finasteride and how it's best-used for preventing genetic onset of balding. If it's the latter...don't do it.