Q: What is the difference between Rogaine for men and Rogaine for women? — G.K., Hawthorne, N.Y.

A: Rogaine, the brand name of generic minoxidil, comes in formulations for both men and women. The men’s versions come in a 5% solution and a 5% foam while women’s products are the 5% foam and 2% solution. Of these, the strongest and most effective is the 5% men’s solution. This is due to the inclusion of propylene glycol, which is a vehicle that helps the active ingredient, minoxidil, to more readily penetrate the scalp. As the other products do not contain propylene glycol, they may be slightly less effective.

Instructions for use also differ on the label between the men’s and women’s products. All products (5% men’s solution, 5% men’s foam, 2% women’s solution) recommend twice daily use, except for the 5% women’s foam which recommends once daily application. In reality, a thorough once daily application seems to be nearly as effective as twice daily for all version of topical minoxidil.

While the 5% solution may be stronger, it is more irritating to the scalp and more difficult for some to tolerate. Some people have a sensitivity to the added propylene glycol and will experience redness, burning, itching, and irritation. If this occurs, patients should switch to the 5% foam or 2% solution. We also recommend that patients use enough of the medication when they apply to adequately cover the treatment area of the scalp. Often, this means using 2 or 3 capfuls of foam or 2-3 droppers full of the solution (2-3mL).

It is important to understand, that contrary to the more restrictive package indications, it works in all areas of the scalp where there is thinning. It is not only for use in the crown. Many patients find that evening application allows the full 4-6 hours of contact time necessary for absorption and that the product will dry overnight and no longer look greasy in the morning. Results can appear as early as 3-6 months, but we often advise using minoxidil for a full year before judging its efficacy. As the hair is always cycling and growing, the product will need to be continued daily for ongoing benefit.