> Yeah - it's a selective testosterone blocker, kind of, and tries to target the part that causes male pattern baldness without lowering overall T Levels.

> I assume it still blocks enough hormones to cause mood shifts or other effects?

Endocrinology is a lot more complicated than you're giving it credit for. DHT blockers don't necessarily lower testosterone levels; they can actually increase it (although even then, the mechanism isn't as direct as you might think).

It's neither established nor a given that any side effects of finasteride have anything to do with effects on testosterone or hormone levels at all. A lot of people make that assumption, and there's reason to suspect there's truth to that hypothesis, but it's completely possible it's an unknown side effect of the drug, and there hasn't been enough study into the mechanism to understand it (in part because the side effects are relatively rare and weakly established).

It’s not a testosterone blocker at all. It blocks 5-alpha reductase, an enzyme that converts testosterone to DHT. It can actually increase serum testosterone by more than 10%.

As for DHT, that hormone doesn’t appear to have much significance for adult males. It’s critically important in puberty, though!

Blocking the conversion of testosterone to DHT (the effect of this medication) causes an indirect and minor increase in both testosterone and œstrogen levels, although DHT is more potent than testosterone for the receptors in many tissues.