What is seborrheic dermatitis?
Seborrheic dermatitis (SD) is an inflammation of the upper layers of the skin that causes a scaly, itchy rash with or without reddened skin. It can appear in many regions throughout the body.
Common sites for seborrheic dermatitis include:
- Sides of the nose
- Skin inside and behind the ears
- Middle of the chest
- Skin folds under the arms, breasts and groin
Seborrheic dermatitis differs slightly from two other conditions, seborrhea and dandruff. In seborrhea, the skin is excessively oily but does not become red or scaly. However, seborrhea can progress to SD in some cases. Dandruff features scaling of the scalp, but redness and inflammation is not present.
There are three age groups that are most susceptible to seborrheic dermatitis: infants, middle-aged adults and the elderly. When the disorder appears on the scalp in infants, it is called cradle cap. Cradle cap is considered to be a temporary condition and usually disappears on its own by ages 8 months to 1 year. However, it can appear in children up to 3 years of age. It may also return at puberty.
In some cases, infants may develop seborrheic dermatitis in the diaper area, where it may be confused with diaper rash. Seborrheic dermatitis may also appear on skin folds of infants, such as the eyelids, ears, nose, and groin.
Adults are more likely to experience seborrheic dermatitis of the face and chest. In addition, they are more likely to experience recurring episodes of SD over their lifetime. Episodes may be triggered by factors such as seasonal changes, stress or other illness.
Signs and symptoms of SD
Symptoms of seborrheic dermatitis include loose scales on the skin that may be greasy or dry, and which are often white to yellowish in color. They may or may not appear over reddened skin. Seborrheic dermatitis usually appears on the scalp, sides of the nose, eyebrows, eyelids, skin behind the ears and middle of the chest. It also may appear on the navel, buttocks, area between the shoulder blades, and skin folds under the arms, breasts and groin. In men, seborrheic dermatitis may be worse under beards and mustaches, and itching tends to be more intense in those with male pattern baldness.
Other symptoms associated with SD include:
- Itchiness. Excessive scratching raises the danger of secondary skin infection.
- Plaques. These are flat areas greater than 1 centimeter (about half-inch) in which the skin changes color.
- Eye disorders. Burning of the eyes may indicate conjunctivitis, inflammation of the inner lining of the eye characterized by redness and discharge. A disorder called seborrheic blepharitis may occur when scales accumulate at the base of the eyelashes, plugging the follicles and causing redness, inflammation and pain.
- Hair loss.
The duration of these symptoms vary from person to person. They may last for weeks, or even years.
Diagnosis and treatment for seborrheic dermatitis
A physician will perform a complete physical examination and compile a thorough medical history when diagnosing seborrheic dermatitis. In most cases, it can be diagnosed based on a visual examination and patient symptoms. However, in some cases laboratory tests (e.g., skin biopsy) may be performed to rule out other conditions.
In some cases, seborrheic dermatitis gets better on its own without treatment. However, it improves faster when proper treatment is administered. The main therapy for seborrheic dermatitis is diligent and consistent shampooing of the scalp and washing of the skin. Washing is important to remove the loose scales so that the underlying skin can be treated.
Gentle shampooing with a mild formulation can help relieve symptoms of cradle cap in infants. Mineral oil or olive oil can be applied to the infants head prior to shampooing to loosen and soften scales. In many cases, this will help clear the cradle cap.
Adult patients may need a dandruff shampoo or other medicated shampoo to treat seborrheic dermatitis of the scalp. These over-the-counter and prescription shampoos contain ingredients that counteract the buildup of skin cells. These ingredients include tar, zinc pyrithione, selenium sulfide, ketoconazole or salicylic acid.
Medications such as corticosteroids, antifungals and topical sulfur treatments are sometimes used to treat seborrheic dermatitis that affects the face or another part of the body. These drugs may also be used to treat severe cases of SD of the scalp. Tacrolimus or pimecrolimus may also be applied to skin to relieve inflammation and reduce the risk of skin atrophy (thinning) from overuse of corticosteroids.
Medication formulations are likely to be much stronger for adults than for children. In some cases, patients may also need medication to treat secondary infections associated with seborrheic dermatitis. For instance, seborrheic blepharitis (a condition in which scales accumulate at the base of the eyelashes) is often treated with a hydrocortisone ointment that is applied to the eyelashes.
Patients should not use any over-the-counter or prescription medications without first consulting a physician.
Seborrheic dermatitis cannot be prevented. However, patients can control the condition by following their physician's treatment recommendations.
What might complicate it?
Secondary infections, exfoliative erythroderma, weight loss, mental and emotional problems, and poor general health may complicate the dermatitis.
Predicted outcome depends on the underlying cause. If the agent causing contact dermatitis can be identified and avoided, the skin inflammation will usually clear itself within a few weeks. Dermatitis from unknown cause must be treated symptomatically as needed.
Last updated 6 September 2019