Is hair loss prevention shampoo effective?

Since this spring, I've been losing a lot of hair suddenly. I lose a handful of hair not only when washing my hair but also when drying it. I'm afraid to comb my hair. Women say that hair loss starts from the crown, so I'm worried. I'm planning to buy anti-hair loss shampoo to prevent further hair loss, but has anyone experienced the effects of anti-hair loss shampoo? If so, please recommend some.