I've read using Rogaine (minoxidil) once a day is just as effective as twice a day. Is this true?

Follow directions. for use. As with all medications, it is very important that you use Rogaine (minoxidil) only as directed, and the proper dose will be different for different patients. Follow your doctor's orders or the directions on the label. Usual recommendations are to use it twice a day. You may not get desired results with once a day use.