Seborrheic dermatitis is a very common, chronic skin condition that causes red patches with overlying greasy, yellow scales to appear on the skin. These patches are believed to develop as a result of the body mounting an inflammatory response to a skin bug called Malassezia yeast.

Frequent Symptoms

Seborrheic dermatitis can develop at any age but most commonly develops in infants between 2 months to 12 months of age, and then later in adolescents and adults between the ages of 30 and 60.

Adult Symptoms

In adults, seborrheic dermatitis causes flaky, scaly patches on the skin that are itchy, moist, and yellowish in color. Underneath these scaly patches, the skin is generally red.

The patches of seborrheic dermatitis develop on areas of the skin that contain a large number of sebaceous (oil-producing) glands, such as the face (including the ears, eyebrows, and eyelids) and scalp.

Dandruff is actually a mild form of seborrheic dermatitis.

Besides the scalp and face, other areas of the body that may be affected by seborrheic dermatitis include the upper chest and back, armpits, and groin.

Infant Symptoms

Many infants develop a type of seborrheic dermatitis called cradle cap, which causes thick and scaling patches to form on the baby's scalp. Like with adults, these patches are greasy and yellow to brown in color.

While cradle cap is harmless—it often causes no symptoms to the baby and usually goes away on its own within a few months—the rash can be distressing to the parent.

Some babies also develop seborrheic dermatitis on the neck and face, like on the eyelids, ears, or around the nose. Patches in the groin area may also develop and be confused for a diaper rash. Less commonly, babies develop scaling patches that cover their bodies.

Complications

Mostly in adults (and usually with more severe cases), if seborrheic dermatitis is left untreated, a secondary bacterial infection may occur. This can cause increased redness, tenderness, and oozing or weeping of the patch and the surrounding skin.

Another potential complication of seborrheic dermatitis is related to the side effects of treatment. In adults, seborrheic dermatitis is often a chronic condition that requires on and off treatment to reduce inflammation and symptoms.

While low-dose topical (on the skin) corticosteroid therapy is an effective medication for treating seborrheic dermatitis, long-term use can cause side effects like thinning of the skin and telangiectasias (dilated blood vessels).

This is why doctors generally prefer milder agents to start, such as antifungal creams or medicated shampoos, and if needed, a non-steroid topical medication like Protopic (tacrolimus) or Elidel (pimecrolimus).

When to See a Doctor

It's always sensible to see your doctor for any new rash, and suspicion of seborrheic dermatitis is no exception. This is because there are other common skin conditions that can cause symptoms similar to those seen in seborrheic dermatitis.

Some of these conditions include:

Less commonly, secondary syphilis can trigger a widespread rash that can mimic the patches of seborrheic dermatitis. Facial seborrheic dermatitis may also mimic the classic "butterfly rash" seen in systemic lupus erythematosus (SLE).

To differentiate among these conditions, in addition to a medical history and physical examination, a dermatologist may perform a skin scraping/KOH test or a skin biopsy.

A Word From Verywell

If you think you or your child has symptoms of seborrheic dermatitis, please speak with your doctor. For babies with just cradle cap, treatment may not be necessary. However, for babies with a more extensive rash, or for adults, prescription medication (in addition to self-care measures) may be warranted.