@SarahGen-- I just started using l-lysine for this purpose. L-lysine has many benefits because it's an essential amino acid required by many different cells in our body. Hair also contains l-lysine, so it can definitely improve the quality of hair and reduce hair loss. Unfortunately, it's not a well known fact. It also doesn't help that there aren't many studies being done on this connection. And many people are not willing to try something if they don't see many studies proving that it works.
However, it works for my sister and I've started seeing results as well. In the recommended dose, l-lysine doesn't have much side effects and it's available at all pharmacies. So it wouldn't hurt to try it. I recommend combining it with biotin supplements. That's what I'm doing.