Skin absorbtion Vs Scalp absorbtion

Hi - there are many anecdotal reports of people using the hair growth drug Minoxidil on their faces to promote/ improve beard growth.

Reading these user diaries and seeing before and after pictures shows it obviously works - but my question is regarding the safety of this. There seems to be a higher incidence of side effects and I wonder if it's down to the absorbtion rate of Minoxidil on the face and whether this is more prone to go systematic?

I am 35 myself with very little cheek hair and would liek to try and improve it this way, but I want to go about it as safely as possible.