I’ve recently read on a couple of websites that the silicone compound Dimethicone, an ingredient in most shampoos and conditioners, could impede the absorption of topical minoxidil products (eg. Rogaine). The theory is that this ‘slilcone oil’ leaves a thin film on the scalp (even after rinsing) that prevents the topical solution from penetrating. Could this be the reason that many men see little or no result from Rogaine, while a minority of patients see significant regrowth of hair? Should all Rogaine users ensure that their shampoos and conditioners are dimethicone-free?
It is, of course, just a theory that dimethicone impacts Rogaine (minoxidil)’s absorption…. but if you’re concerned about it you can buy dimethicone free shampoo. I do not believe that any single process or product will be responsible for drug absorption or modifying the results of specific drugs. Men have seen variable results from this medication since it was first released as a topical for hair growth. I don’t have an exact explanation why, though.
I’ve actually posted something about this before — Is Dimethicone in Shampoo Preventing Minoxidil Scalp Penetration? — and the commenters at the bottom have some added information that you might be interested in.