Published studies on Topical finasteride and systemic Dutasteride

https://pubmed.ncbi.nlm.nih.gov/10495374/

https://pubmed.ncbi.nlm.nih.gov/26636418/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4969473/

All three of these research papers discuss the impact on scalp and systemic DHT.  Dutasteride reported a low incidence of sexual side effects 1.7% but although this number is thought to be low, if you subtract the placebo group from the sexual side effects group on finasteride it comes out about 2%.