Does glycerin make minoxidil formulas less effective?
Answer: The short answer is no. As minoxidil without propylene glycol should be equivalently effective as minoxidil with propylene glycol. Both glycerin and propylene glycol are pharmacologically inactive ingredients in the minoxidil products. They are used in minoxidil solutions because (1) they are humectants, i.e. they help to moisturize the skin and help protect from the drying effect of the alcohol; (2) they increase and stabilize the solubility of minoxidil; and (3) they keep a small quantity of minoxidil on the surface of the scalp to allow for continued absorption after the alcohol necessary to the base solution has penetrated.