This skin condition can show up anywhere, but often happens on the scalp. It causes the body to make too many new skin cells. This buildup can form thick, crusted scales that can feel itchy or sore.
You usually treat psoriasis with steroid creams or ointments. Shampoos with tar or salicylic acid may also be helpful. Ultraviolet light therapy (shining UV light on the skin to slow the growth of skin cells) is another option. Severe cases may need medication taken by mouth or in an injection.
Lichen planus affects the skin or mouth. No one knows what causes it, but there are a number of theories, ranging from stress to genetics. It may also be linked to the hepatitis B or C virus, dental materials, or thyroid disease. Doctors believe lichen planus is an autoimmune disease, which means your immune system attacks your own body by mistake. Medications used to treat high blood pressure, heart disease, and arthritis can sometimes cause a lichen planus-like irritation.
People who have lichen planus develop flat-topped, purple, or reddish bumps on their skin. And they usually itch. Other symptoms include redness, irritation, and (sometimes permanent) hair loss. Although the bumps will eventually go away on their own, treatment or removal of the trigger can ease symptoms and clear up the rash quickly. The main treatment is steroid medications that are rubbed on, injected, or taken by mouth. Retinoid medications used for acne may also help. Antihistamines (such as Benadryl) or soothing baths can help the itching. Sometimes doctors use a type of ultraviolet light therapy called PUVA (psoralen plus UVA radiation) or antibiotics.