In some cases, shampoo isn't going to do the trick. If your itchy scalp proves stubborn, make an appointment with a health care professional. For example, if Rid or Nix didn't finish the job with head lice, there are also prescription remedies (Sklice and Ulesfia) that can kill the parasites.
Psoriasis treatment progresses in stages. A doctor may start with a topical medication that goes on the scalp. The next step is light therapy, either with lasers or without. Excimer lasers can treat plaques without harming the surrounding skin. The U.S. Food and Drug Administration (FDA) has also approved several medications for psoriasis -- some are injected, while others are infused or simply swallowed [source: American Academy of Dermatology].
Ringworm treatment can take awhile -- six weeks or more. The usual fix is an oral antifungal medication, such as Grifulvin V, Gris-Peg or Lamasil, that can be sprinkled on food.