What causes dandruff? How can I treat it?

Yeast. Dandruff is seborrhiec dermatitis in the scalp. This is due to an overgrowth of yeast named pityrosporum ovale. Some make sebum (oils) especially preferential for them to grow. If your immune system reacts to it, your skin becomes inflamed red and flaky, thus the dandruff. Start by using head and shoulder, nizoral, (ketoconazole) neutrogena tgel or tsal shampoo, lather and leave in for 5-10min before rinsing.
Dry scalp. Use a dandruff shampoo such as pert to moisturize your scalp. The dryness will go away and so will the flaking skin or dandruff.
Dandruff. Dandruff is a common scalp condition in which small pieces of dry skin flake off of the scalp. If you have dark hair or you’re wearing dark colors, you may notice the flakes in your hair or on your shoulders. Dandruff may also make your scalp itch. https://www.aad.org/public/skin-hair-nails/hair-care/how-to-treat-dandruff.