Seborrheic dermatitis is an inflammation of the upper layers of the skin. It typically causes a scaly, itchy rash that often appears with reddened skin on the scalp, sides of the nose, eyebrows, eyelids, skin behind the ears and middle of the chest. It may also appear on the navel, buttocks and skin folds under the arms, breasts and groin.

Seborrheic dermatitis results from an overproduction of skin cells and sebum, the skin’s natural oil. There are three age groups that are most likely to develop seborrheic dermatitis: infants, middle-aged adults and the elderly. When the disorder appears on the scalp in infants, it is called cradle cap.

Seborrheic dermatitis 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:

• Scalp
  
  
• Sides of the nose
  
  
• Eyebrows
  
  
• Eyelids
  
  
• Skin inside and behind the ears
  
  
• Middle of the chest
  
  
• Navel
  
  
• Buttocks
  
  
• Skin folds under the arms, breasts and groin

Seborrheic dermatitis occurs due to an overproduction of skin cells and sebum, the skin’s natural oil. It is a chronic (ongoing) and intermittent rash, with no cure available. However, treatments are available to control it. The condition is not contagious.

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 seborrheic dermatitis 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 seborrheic dermatitis over their lifetime. Episodes may be triggered by factors such as seasonal changes, stress or other illness.

Seborrheic dermatitis occurs as a result of an overproduction of skin cells and sebum, the skin’s natural oil. However, the exact cause of this process is unknown. It appears to be associated with an overgrowth of a normal skin yeast fungus, but experts are unsure whether the fungus causes flaking or skin flaking allows for the overgrowth of the fungus.

In many cases, seborrheic dermatitis appears to be related to family history and is more common in people with oily skin and hair. In some cases it is associated with psoriasis or acne. People who live in northern climates may experience seasonal flare-ups when the weather turns cold and the air becomes drier, with remission occurring in the summer months. African Americans, however, are more likely to flare-up in the summer months. 

Other factors known to trigger seborrheic dermatitis include:

• Stress
  
• Fatigue
  
• Illness
  
• Infrequent hair and skin cleaning
  
• Use of lotions that contain alcohol
  
• Obesity
  
• Hormonal changes

Several conditions also are associated with seborrheic dermatitis. They include:

• Neurological conditions, such as Parkinson’s disease, epilepsy, head injuries and stroke
  
  
• Medical conditions that stress the body, such as heart attacks
  
  
• Immune system disorders, including human immunodeficiency virus (HIV)
  
  
• Vitamin B deficiencies

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 seborrheic dermatitis 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.

Cradle cap is the name given to seborrheic dermatitis that appears on the scalp in infants. It usually appears as thick, crusty, brown or yellow scales on the scalp and around the hairline. Seborrheic dermatitis may also appear on skin folds of infants, such as the eyelids, ears, nose and groin. Excessive scratching can lead to additional inflammation, bleeding and mild infections.

The duration of these symptoms vary from person to person. They may last for weeks, or even years.

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 seborrheic dermatitis 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.

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to seborrheic dermatitis:

1. Do my symptoms suggest seborrheic dermatitis?
   
   
2. What may have caused me to develop the condition?
   
   
3. Can I spread the condition to other people?
   
   
4. Will the condition spread to other parts of my body?
   
   
5. What are my treatment options?
   
   
6. How long will it take for my symptoms to subside?
   
   
7. Am I likely to have future episodes of seborrheic dermatitis?
   
   
8. What triggers may cause me to develop seborrheic dermatitis again in the future?
   
   
9. Will my child outgrow cradle cap? If so, when?
   
   
10. How can I prevent a secondary infection from developing?