The hair cycle normally consists of growing, resting and falling hairs and there is a delicate balance between these stages of hair cycle. Normally hair should regrow but if it is not happening, you should consider seeing a dematologist. Further information is in the following weblink https://www.aad.org/public/diseases/hair-and-scalp-problems/hair-loss
Next Steps
Serious side effects with finasteride are extremely rare, though it can happen. Finasteride is US-FDA approved while dutasteride awaits approval for usage in male pattern baldness.