How come some men get side effects from Propecia and some don't

I was wondering about this too as the side effects are what has kept me (and a lot of people) away from it.
One thing I was thinking is that some people might've had massive DHT levels in the past which caused balding, but no longer do, and then suppressing it further causes problems. Perhaps it best suits people who are continuously a bit high on DHT.

Just ignorant speculation really

The medical community has been pondering over this since the beginning of the medical community. People respond to different medications differently. It would be wonderful if someone could figure out why.

If every man that took fin had baseline blood and hormone tests done, then got tests done again after/during if sides occurred, we may have an idea! But we don't

If every patient responded in the exact same way to every treatment or medication things might actually be too boring.

Why is the sky blue? It just is. Actually there is an actual reason why people respond differently to propecia its just a complicated combination of poorly understood systems and complex relationships no one ever figured out how they all work together. I mean systems like say the immune system are very poorly understood and play a big role in MPB probably far downstream of that initial androgen trigger. Without understanding the immune response what hope is there to piece together the other systems like say blood flow with respect to time and all the other things? Its just too complicated for our limited resources and current knowledge.

Everyone has a different metabolic process and biochemistry active in the diversity of men out there and that is along with the genetic markers that trigger stages of disease, cellular growth and decay etcetera. Propecia interacts with ONLY one factor as opposed to the many coexisting in the body over a period of time the endrocrinology and androgenic hormone ratios in the body at given time that the receptors in the hair follicles have been genetically programmed to be sensitvie and wither and eventually grow dormant in men with MPB. The prostate and production of testosterone and seminal fluid the cause for reporduction and virility in men also causes the byproduct of DHT to lead to the march of MPB only the men who retain their hair over time have to a larger degree the absence of the sensitive binding receptors that cause baldness. Eventually any reasonable cure for baldness would have to be a delivery system that with one injection in the body impacts , resequences and offsets the genetic marker for baldness switching it off to a dormant state from an early age thus baldness skips that generation of individuals.