Seborrheic Dermatitis. Causes, Triggers, and Treatment

Seborrheic dermatitis is a common, chronic, life-long condition. It is not contagious, nor is it related to poor hygiene. It is often referred to as dandruff when it occurs on the scalp and seborrheic dermatitis when it appears elsewhere on the body.

Seborrheic Dermatitis affects millions of people worldwide, most commonly Caucasian men 30 to 60 years of age. Luckily, many options are available to help treat it and keep it under control.

Causes for seborrheic dermatitis

While the exact cause of seborrheic dermatitis is unknown, many factors play a role, including:

• Overgrowth of the yeast Malassezia. The higher the levels of yeast, the worse the disease is.
• Disrupted epidermal barrier. This disruption may be genetic or due to yeast overgrowth. Malassezia has an enzyme that breaks down the fats in the epidermal barrier. This disruption in the skin’s barrier allows more bacteria and irritants to enter the skin and cause infection and inflammation.
• Increased activity of the sebaceous glands. These sebaceous glands are responsible for oil production. The highest incidence of seborrheic dermatitis is during times in our lives when our androgen levels are highest. These androgens cause the sebaceous glands to produce oil.
• Elevated levels of androgen hormones. Androgens cause excess oil production.
• Elevated levels of skin lipids (free fatty acids and triglycerides). These promote Malassezia growth.
• Immune system. A suppressed immune system leads to more severe cases of seborrheic dermatitis.
• Family history. Recently, gene mutations have been discovered that may be responsible for seborrheic dermatitis.

Triggers for seborrheic dermatitis

There are some things to avoid that can worsen seborrheic dermatitis:

• Stress.
• Cold, dry water.
• Products with alcohol that come in contact with the affected areas.
• Harsh soaps and shampoos.

Signs and symptoms of seborrheic dermatitis

Seborrheic dermatitis is characterized by a rash on the most sebaceous (oiliest) parts of the body.

• Scalp, face (most commonly ears, nose, eyelids, and brows), chest, groin, navel, and skin folds on the extremities.
• May itch or burn.
• White flakes.
• Thick, crusted, greasy yellow flakes.
• Redness.

Medical conditions associated with seborrheic dermatitis

Many medical conditions occur more frequently in people with seborrheic dermatitis:

• Skin conditions. Psoriasis, acne, and rosacea.
• Immunosuppression. Transplant recipients, lymphoma, other cancers, and HIV.
• Neurologic. Parkinson's disease, epilepsy.
• Psychiatric. Depression, eating disorders, and alcoholism.
• Congenital. Down’s syndrome.
• Cardiac. Heart attack and stroke.

Medications that worsen seborrheic dermatitis

Some medications can worsen seborrheic dermatitis as well.

• Lithium.
• Psoralen.
• Interferon.
• Buspirone.
• Haloperidol.
• Chlorpromazine.
• Androgens.

Diagnosing and treating seborrheic dermatitis

Seborrheic dermatitis is often diagnosed solely by clinical examination and the patient's history. If the diagnosis is unclear, other options include a skin biopsy or skin scraping.

While there is no cure for seborrheic dermatitis, several over-the-counter products and prescription medications can help alleviate the symptoms of seborrheic dermatitis.

Over-the-counter products

• Several shampoos, which contain zinc pyrithione, selenium sulfide, coal tar, salicylic acid, or ketoconazole, work well on seborrheic dermatitis. It is best to massage the shampoo into your scalp and leave it on for five minutes to allow it to penetrate before rinsing. Also, alternate the shampoo ingredients monthly for optimal results.
• Hydrocortisone cream 1% is an over-the-counter medication that can be used sparingly and infrequently for seborrheic dermatitis on the face. Long-term daily application of steroid creams, like hydrocortisone, can thin the skin, cause acne, and lead to striae (stretch marks).

Prescription topical medications

• Steroids can decrease inflammation and calm the skin to keep seborrheic dermatitis under control. Long-term daily application of steroid creams can thin the skin, cause acne, and lead to striae.
• Calcineurin inhibitors (Protopic and Elidel) act like steroids but do not have the same side effects and can be used daily.
• Topical antifungals come in various formulations, such as creams, ointments, gels, sprays, shampoos, and foams. They are safe to use daily to keep seborrheic dermatitis under control.

Prescription oral medications

• Steroid pills and injections are rarely used for seborrheic dermatitis and only in very severe cases when nothing else works. They are the last resort because of the side effects.
• Antifungal pills are reserved for severe cases because of the side effects and drug interactions.

Phototherapy with UVB light can help reduce the inflammation from seborrheic dermatitis in severe cases. Natural sunlight is also beneficial, but there is a risk of skin cancer.