by dr. lam » Sun Nov 07, 2010 8:18 pm
hmmm, i have not heard of puffy eyes. that is interesting. in general, ideally rogaine should remain on your scalp during the day but i cannot say for certain how long exactly to attain the results. the 4 hours you may be referencing is the half life of rogaine in the bloodstream. that has little relevance to how long you should keep it on your scalp or how long it lasts. some argue that rogaine on the scalp can last up to 22 hours but that has not been conclusively proven. thanks for the question.