In my opinion, the proper way to view this would be that oral finasteride has a low-moderate risk of side effects whereas topical finasteride has a very low low risk of side effects. But to assume the risk is zero would not be accurate. First, a very small amount is absorbed into the blood stream when topical finasteride is used. This may be 1/10th to 1/20th of the amount that would be absorbed if pills were used. Second, all men differ in sensitivity to DHT reductions. Men who are very sensitive to even small changes could develop symptoms. Studies have shown that topical finasteride still reduces serum DHT. Of course the degree of reduction is not the same as oral finas but nevertheless topical finasteride does reduce serum DHT. I am not of the opinion that topical finasteride thas zero side effects. However, I am of the opinion that the chances of side effects are very low.
