Dermatitis is a general term that describes a common skin irritation. It has many causes and forms and usually involves itchy, dry skin or a rash. Or it might cause the skin to blister, ooze, crust or flake off. Three common types of this condition are atopic dermatitis (eczema), seborrheic dermatitis and contact dermatitis.

Dermatitis isn't contagious, but it can make you feel uncomfortable and self-conscious. Moisturizing regularly helps control the symptoms. Treatment may also include medicated ointments, creams and shampoos.

Each type of dermatitis tends to occur on a different part of your body. Signs and symptoms may include:

• Itchiness (pruritus)
• Dry skin
• Rash on swollen skin that varies in color depending on your skin color
• Blisters, perhaps with oozing and crusting
• Flaking skin (dandruff)
• Thickened skin
• Bumps in hair follicles

When to see a doctor

See your doctor if:

• You're so uncomfortable that you're losing sleep or are distracted from your daily routines
• Your skin becomes painful
• You suspect that your skin is infected
• You've tried self-care steps but your signs and symptoms persist

A common cause of dermatitis is contact with something that irritates your skin or triggers an allergic reaction — for example, poison ivy, perfume, lotion and jewelry containing nickel. Other causes of dermatitis include dry skin, a viral infection, bacteria, stress, genetic makeup and a problem with the immune system.

Common risk factors for dermatitis include:

• Age. Dermatitis can occur at any age, but atopic dermatitis (eczema) is more common in children than adults, and it usually begins in infancy.
• Allergies and asthma. People who have a personal or family history of eczema, allergies, hay fever or asthma are more likely to develop atopic dermatitis.
• Occupation. Jobs that put you in contact with certain metals, solvents or cleaning supplies increase your risk of contact dermatitis. Being a health care worker is linked to hand eczema.
• Health conditions. Health conditions that put you at increased risk of seborrheic dermatitis include congestive heart failure, Parkinson's disease and HIV/AIDS.

Wear protective clothing if you are doing a task that involves irritants or caustic chemicals.

Avoid dry skin by adopting these habits when bathing:

• Take shorter baths and showers. Limit your baths and showers to 5 to 10 minutes. Use warm, rather than hot, water. Bath oil also may be helpful.
• Use a gentle, nonsoap cleanser. Choose unscented nonsoap cleansers. Some soaps can dry your skin.
• Dry yourself gently. After bathing, gently pat your skin dry with a soft towel.
• Moisturize your skin. While your skin is still damp, seal in moisture with an oil, cream or lotion. Try different products to find one that works for you. Ideally, the best one for you will be safe, effective, affordable and unscented. Two small studies showed that applying a protective moisturizer to the skin of infants at high risk of atopic dermatitis reduced the incidence of the condition by up to 50%.

To diagnose dermatitis, your doctor will likely talk with you about your symptoms and examine your skin. You may need to have a small piece of skin removed (biopsied) for study in a lab, which helps rule out other conditions.

Patch testing

Your doctor may recommend patch testing on your skin. In this test, small amounts of different substances are applied to your skin and then covered. The doctor looks at your skin during visits over the next few days to look for signs of a reaction. Patch testing can help diagnose specific types of allergies causing your dermatitis.

The treatment for dermatitis varies, depending on the cause and your symptoms. In addition to the lifestyle and home remedies recommendations below, dermatitis treatment might include one or more of the following:

• Applying to the affected skin corticosteroid creams, gels or ointments
• Applying to the affected skin certain creams or ointments that affect your immune system (calcineurin inhibitors)
• Exposing the affected area to controlled amounts of natural or artificial light (phototherapy)
• Using oral corticosteroids (pills) or injectable dupilumab, for severe disease
• Using wet dressings, a medical treatment for severe atopic dermatitis that involves applying a corticosteroid and wrapping it with wet bandages

These self-care habits can help you manage dermatitis and feel better:

• Moisturize your skin. Routinely applying a moisturizer can help your skin.
• Use anti-inflammation and anti-itch products. Hydrocortisone cream might temporarily relieve your symptoms. Oral antihistamines, such as diphenhydramine, may help reduce itching. These types of products are available without a prescription.
• Apply a cool wet cloth. This helps soothe your skin.
• Take a comfortably warm bath. Sprinkle your bathwater with baking soda or a finely ground oatmeal that's made for the bathtub (colloidal oatmeal). Soak for 5 to 10 minutes, pat dry and apply unscented moisturizer while your skin is still damp. A lotion of 12% ammonium lactate or 10% alpha-hydroxy acid helps with flaky, dry skin.
• Use medicated shampoos. For dandruff, use OTC shampoos containing selenium sulfide, zinc pyrithione, coal tar or ketoconazole.

• Take a dilute bleach bath. This may help people with severe atopic dermatitis by decreasing the bacteria on the skin. For a dilute bleach bath, add 1/2 cup (about 118 milliliters) of household bleach, not concentrated bleach, to a 40-gallon (about 151-liter) bathtub filled with warm water. Measures are for a U.S. standard-sized tub filled to the overflow drainage holes. Soak for 5 to 10 minutes and rinse off before patting dry. Do this 2 to 3 times a week.

  Many people have had success using a dilute vinegar bath rather than a bleach bath. Add 1 cup (about 236 milliliters) of vinegar to a bathtub filled with warm water.

• Avoid rubbing and scratching. Cover the itchy area with a dressing if you can't keep from scratching it. Trim your nails and wear gloves at night.
• Choose mild laundry detergent. Because your clothes, sheets and towels touch your skin, choose mild, unscented laundry products.
• Avoid known irritants or allergens. Try to identify and remove allergens and other factors in your environment that irritate your skin. Avoid rough and scratchy clothing.
• Manage your stress. Emotional stressors can cause some types of dermatitis to flare. Consider trying stress management techniques such as relaxation or biofeedback.

Many alternative therapies, including those listed below, have helped some people manage their dermatitis. But evidence for their effectiveness is mixed. And sometimes herbal and traditional remedies cause irritation or an allergic reaction.

• Dietary supplements, such as vitamin D and probiotics, for atopic dermatitis
• Rice bran broth (applied to the skin), for atopic dermatitis
• 5% tea tree oil shampoo, for dandruff
• Aloe, for seborrheic dermatitis
• Chinese herbal therapy

If you're considering dietary supplements or other alternative therapies, talk with your doctor about their pros and cons.

You may first bring your concerns to the attention of your family doctor. Or you may see a doctor who specializes in the diagnosis and treatment of skin conditions (dermatologist).

Here's some information to help you get ready for your appointment and know what to expect from your doctor.

What you can do

Before your appointment, list your answers to the following questions:

• What are your symptoms, and when did they start?
• Does anything seem to trigger your symptoms?
• What medications are you taking, including those you take by mouth as well as creams or ointments that you apply to your skin?
• Do you have a family history of allergies or asthma?
• What treatments have you tried so far? Has anything helped?

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to talk about in depth. Depending on what type of dermatitis you have, your doctor may ask:

• Do your symptoms come and go, or are they fairly constant?
• How often do you shower or bathe?
• What products do you use on your skin, including soaps, lotions and cosmetics?
• What household cleaning products do you use?
• Are you exposed to any possible irritants from your job or hobbies?
• Have you been under any unusual stress or depressed lately?
• How much do your symptoms affect your quality of life, including your ability to sleep?