Is a prescription shampoo or an OTC shampoo better? Which ingredient in the shampoo seems to work? Is it better to go to a beauty supply store or a drugstore for an OTC product? The flakes in my hair are not very visible but I do have lots of hair loss & thinning. My thyroid is fine, but I have anxiety & stress which contributes to the prob. Also, my head does not itch. I went to a derm who sold me products from DCL Labs which didn't help. My GP thought that is was Seborrheic Dermatitis. Biotin just helps my nails, but not my hair.