Seborrheic dermatitis is a condition in which inflammation in the dermis causes redness, itching and flaking of the skin. Treatment is focused on controlling the inflammation. Most people are affected by seborrheic dermatitis in their scalp (which frequently manifests as dandruff) and face. An easy over the counter product treatment for this is to use a shampoo containing Selenium which helps control seborrheic dermatitis and reduce and sometimes eliminate the itching, redness and flaking of the affected skin. One such example is Selsun Blue (medicated). It is available over the counter in most pharmacies and grocery stores in the shampoo section. Even though it is a shampoo, it does not have to be limited to just hair/scalp. It can be used on all skin surfaces including the face, neck or other areas of the body. A week to two weeks of using this shampoo should show some improvement of your skin. Continue using the shampoo daily to control it.
If the above recommendation doesn't work, there are prescription strength Selenium shampoos which may be more effective. If you want to stick to over the counter products, things like cortisone cream or creams/shampoos with salicylates can be tried to treat seborrheic dermatitis.
If all of the above fail, I would recommend seeing your dermatologist
for further therapy and possibly prescription strength creams which can help this condition.