A number of health conditions, allergies, genetic factors, physical and mental stressors, and irritants can cause dermatitis.
Contact dermatitis
This condition results from direct contact with one of many irritants or allergens.
Common irritants include:
- Laundry soap
- Skin soaps or detergents
- Cleaning products
Possible allergens include:
- Rubber
- Metals, such as nickel; jewelry
- Perfume and fragrances
- Cosmetics
- Weeds, such as poison ivy
- Neomycin and bacitracin, common ingredients in topical antibiotic creams
It takes a greater amount of contact with an irritant over a longer time to cause dermatitis than it takes for an allergen. Once you're sensitized to an allergen, just brief exposure to a small amount of it can cause dermatitis. Once you develop sensitivity to an allergen, you typically have it for life.
Neurodermatitis
Also known as lichen simplex chronicus, this type of dermatitis typically develops when something has created an itchy sensation in a specific area of your skin. This irritation may lead you to rub or scratch your skin repeatedly in that area. Common locations include the ankle, wrist, outer forearm or arm, and the back of your neck.
Possible underlying factors include:
- Dry skin
- Chronic irritation
- Eczema
Seborrheic dermatitis
This condition causes a red rash with yellowish and somewhat "oily" scales, usually on the scalp and sometimes on the face, especially around the ears and nose. It's common in people with oily skin or hair, and it may come and go depending on the season of the year. It's likely that hereditary factors play a role in this condition.
Possible underlying factors include:
- Physical stress
- Neurological conditions, such as Parkinson's disease
In infants, this disorder is known as cradle cap.
Stasis dermatitis
Stasis dermatitis can occur when fluid accumulates in the tissues just beneath the skin — typically on your lower legs — due to a sluggish return of blood from the leg veins back to the heart. The extra fluid interferes with your blood's ability to nourish your skin and places extra pressure against your skin from underneath.
Possible underlying factors include:
- Varicose veins
- Obesity, often extreme
- Other chronic conditions or recurrent infections that affect circulation in your legs, such as pregnancy or deep vein thrombosis
Atopic dermatitis
This condition often occurs with allergies and frequently runs in families in which members have asthma, hay fever or eczema. It usually begins in infancy and may vary in severity during childhood and adolescence. It tends to become less of a problem in adulthood, unless you're exposed to allergens or irritants in the workplace.
Possible underlying factors include a combination of:
- Dry, irritable skin
- A malfunction in the body's immune system
- A genetic tendency for allergic conditions such as asthma, hay fever or eczema
Stress can exacerbate atopic dermatitis, but it doesn't cause it.
Perioral dermatitis
This type of dermatitis may be a form of the skin disorder rosacea, adult acne or seborrheic dermatitis, involving the skin around the mouth or nose.
Possible underlying factors include:
- Makeup
- Moisturizers
- Topical corticosteroids
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