Is there seborrheic dermatitis treatment which could be bought over the counter?

Dandruff treatment: Dandruff (seborrheic dermatitis) is a chronic skin condition that can be treated but not cured. It tends to flare with season changes and when a person is experiencing stress. Over the counter dandruff shampoos are a good place to start treating dandruff and most of the time do a good job helping. Severe dandruff needs to be seen by a doctor for some prescriptions and for possible tests.

If on scalp: If your seborrhea is mainly on your scalp, wash your hair/scalp twice a week with a tar based shampoo. (i know it sounds icky, but tar shampoos don't look or smell like tar). My favorite is neutrogena tar shampoo. Massage it well into the scalp and leave it on 10-15 minutes before rinsing. Once it is cleared up, can reduce uses to once a week to prevent it from flaring up again.