dutasteride is even more powerful than finasteride since it blocks both 5AR enzymes (I & II), thus 99% of DHT production, whereas Finasteride only blocks 5AR type II and thus ~ 70% of serum DHT.
dutasteride blocks 5AR type I which is found in the brain, nobody knows longterm consequences of that. It stands to reason that if it's more powerful than Finasteride, Dutasteride's side effects may be worse.
dutasteride is not approved for hairloss.