Rogaine (chemical name Minoxidil) is one of only two officially approved hair loss treatments in the US and EU. There are a number of mechanisms via which Minoxidil works to grow hair. Nowadays, most people use Rogaine 5% Minoxidil Foam rather than topical Minoxidil. Some people prefer to use high-strength Minoxidil.
The instructions on the packaging tell male users to apply Rogaine foam twice per day. However, many people choose to apply it just once per day instead.
There is some evidence that once a day use of Rogaine (Minoxidil 2% or 5%) is almost as effective as using it twice per day. The half-life of topical Rogaine is 22 hours.
Please closely read all the options in the below poll before voting. You can only vote once, and cannot edit your vote.
Poll: Rogaine Once or Twice per Day?
Due to the poll slowing down this site, I ended it early. Final results are shown below based on a total of 480 votes: