What causes hair on th head to grow faster and thicker?

Rogaine, (minoxidil) Propecia. The only two hair growth products currently on the market with real clinical data to support their use are rogaine (minoxidil) (topical) and Propecia (oral). They work by different mechanisms, so I have my patients use both. Rogaine (minoxidil) is otc, Propecia requires a prescription. The downside is that insurance seldom pays for either one; but Propecia is about to go generic, which should lower the price.
Hair growth. Most common cause of sudden hair growth is hormonal or drug induced. There are many other cause so be sure to see a dermatologist to find out why.