Seborrheic dermatitis is most common in young adults and occurs in areas with a high concentration of sebaceous glands, such as the head, face, forehead, armpits, chest, epididymis, and perineum. The initial appearance is a red rash or patchy fusion with greasy scales or crusts. In severe cases, seborrheic dermatitis may even be accompanied by exudate, and in addition to thick crusts, it may even have an odor and bad smell. If seborrheic dermatitis is more severe it may invade the entire head and cause hair loss. Lesions on the face may also be seen as slightly red patches if seen on the nose, nasolabial folds, etc. If the symptoms of seborrheic dermatitis change more drastically you must seek early medical treatment at a hospital, ask your doctor for a diagnosis, apply topical creams, etc.