The most common form of hair loss (male or female pattern baldness) is determined by age and genetics. Alas, it is quite normal; it can not be prevented or cured. If you have sudden hair loss you should see a physician, not all hair is normal. There is no herb or shampoo to make lost hair grow back.
But according to studies two approved medicines; – Rogaine and Propecia can treat hair loss mostly. According to Dr. Claire Haycox, a dermatologist and associate professor of dermatology at the University of Washington in Seattle, Rogaine is a more tolerable drug.
Rogaine (minoxidil – hair-restoring cream) is sold over counter. It works for some people, but the hair it produces is usually thinner and lighter, and the effects fade with time. It works only while you use it. Rogaine increase the hair growth abnormally with some slight side effects.
Propecia, must be taken orally, used in higher doses to treat an enlarged prostrate, it blocks the hormones that interferes with hair growth. In one study 60% of men showed new hair growth after a year of treatment. But it may cause some side effects too like irritation, itch, swelling etc. especially in pregnant women, cannot take it.