I was browsing the yahoo answers on Rogaine, and read that your body becomes dependant on the active ingredient to grow hair, and is unable to stimulate hair growth on its own after prolonged use. This seems to be true, as using this product does not guarantee permanent regrowth of hair unless you continue to apply it for as long as you want hair growth.

Rogaine’s active ingredient was at first used as a vasodilator to treat high blood pressure… researchers discovered by chance that it had alternate function in stimulating hair growth and also reversing baldness.
In some cases Rogaine has been known to increase hair loss after initial use! There are a variety negative side effects that can be found easily using wikipedia (see sources) – but it would be best for you to consult a physician before using the drug, as you may have other health conditions which may be implicated in your use of Rogaine! Best of luck… let us know how you do