Dermatitis is a general term used to describe inflammation of the skin.
Most types of dermatitis are characterized by an itchy pink or red rash.
Contact dermatitis is an allergic reaction to something that irritates the skin and is manifested by one or more lines of red, swollen, blistered skin that may itch or seep. It usually appears within 48 hours after touching or brushing against a substance to which the skin is sensitive. The condition is more common in adults than in children.
Contact dermatitis can occur on any part of the body, but it usually affects the hands, feet, and groin. Contact dermatitis usually does not spread from one person to another, nor does it spread beyond the area exposed to the irritant unless affected skin comes into contact with another part of the body. However, in the case of some irritants, such as poison ivy , contact dermatitis can be passed to another person or to another part of the body.
Atopic dermatitis is characterized by itching , scaling, swelling, and sometimes blistering. In early childhood it is called infantile eczema and is characterized by redness, oozing, and crusting. It is usually found on the face, inside the elbows, and behind the knees.
Seborrheic dermatitis may be dry or moist and is characterized by greasy scales and yellowish crusts on the scalp, eyelids, face, external surfaces of the ears, underarms, breasts, and groin. In infants it is called cradle cap.
Allergic reactions are common. No formal statistics are kept on such attacks.
Causes and symptoms
Allergic reactions are genetically determined, and different substances cause contact dermatitis to develop in different people. A reaction to resin produced by poison ivy, poison oak , or poison sumac is the most common source of symptoms. It is, in fact, the most common allergy in the United States, affecting one of every two people in the country.
Flowers, herbs, and vegetables can also affect the skin of some people. Burns and sunburn increase the risk of dermatitis developing. Chemical irritants that can cause the condition include:
- detergents and soaps
- fabric softeners
- glues used on artificial nails
- topical medications
Contact dermatitis can develop when the first contact occurs or after years of use or exposure.
Seborrheic dermatitis (for which there may also be a genetic predisposition) is usually caused by overproduction of the oil glands. In adults it can be associated with diabetes mellitus or gold allergy. In infants and adults it may be caused by a biotin deficiency.
When to call the doctor
A doctor or other healthcare provider should be consulted when rashes appear. With some experience, common rashes can be accurately identified by parents. Rashes that cannot be accurately identified should be referred to competent healthcare professional for identification and possible treatment.
The diagnosis of dermatitis is made on the basis of how the rash looks and its location. The doctor may scrape off a small piece of affected skin for microscopic examination or direct the person to discontinue use of any potential irritant that has recently come into contact with the affected area. Two weeks after the rash disappears, the person may resume use of the substances, one at a time, until the condition recurs. Eliminating the substance most recently added should eliminate the irritation.
If the origin of the irritation has still not been identified, a dermatologist may perform one or more patch tests, which involves dabbing a small amount of a suspected irritant onto skin on the person's back. If no irritation develops within a few days, another patch test is performed. The process continues until the person experiences an allergic reaction at the spot where the irritant was applied.
Treating contact dermatitis begins with eliminating or avoiding the source of irritation. Prescription or over-the-counter corticosteroid creams can lessen inflammation and relieve irritation. Creams, lotions, or ointments not specifically formulated for dermatitis can intensify the irritation. Oral antihistamines are sometimes recommended to alleviate itching, and antibiotics are prescribed if the rash becomes infected. Medications taken by mouth to relieve symptoms of dermatitis can make skin red and scaly and cause hair loss.
People who have a history of dermatitis should remove their rings before washing their hands. They should use bath oils or glycerin-based soaps and bathe in lukewarm saltwater.
Patting rather than rubbing the skin after bathing and thoroughly massaging lubricating lotion or nonprescription cortisone creams into still-damp skin can soothe red, irritated nummular dermatitis. Highly concentrated cortisone preparations should not be applied to the face, armpits, groin, or rectal area. Periodic medical monitoring is necessary to detect side effects in people who use such preparations on rashes covering large areas of the body.
Coal-tar salves can help relieve symptoms of nummular dermatitis that have not responded to other treatments, but these ointments have an unpleasant odor and stain clothing.
Coal-tar shampoos may be used for seborrheic dermatitis that occurs on the scalp. Sun exposure after the use of these shampoos should be avoided because the risk of sunburn of the scalp is increased.
Some herbal therapies can be useful for skin conditions. Among the herbs most often recommended are:
- burdock root ( Arctium lappa )
- calendula ( Calendula officinalis ) ointment
- chamomile ( Matricaria recutita ) ointment
- cleavers ( Galium ssp.)
- evening primrose oil ( Oenothera biennis )
- nettles ( Urtica dioica )
Contact dermatitis can be treated botanically and homeopathically. Grindelia ( Grindelia spp.) and sassafras ( Sassafras albidum ) can help when applied topically. Determining the source of the problem and eliminating it is essential. Oatmeal baths are very helpful in relieving the itch. Bentonite clay packs or any mud-pack draws the fluid out and helps dry up the lesions. Cortisone creams are not recommended.
Selenium-based shampoos, topical applications of flax oil and/or olive oil, and biotin supplementation are among the therapies recommended for seborrheic dermatitis.
Dermatitis is often chronic, but symptoms can generally be controlled.
Contact dermatitis can be prevented by avoiding the source of irritation. If the irritant cannot be avoided completely, the person should wear gloves and other protective clothing whenever exposure is likely to occur.
Immediately washing the exposed area with soap and water can stem allergic reactions to poison ivy, poison oak, or poison sumac, but because soaps can dry the skin, people susceptible to dermatitis should use them only on the face, feet, genitals, and underarms.
Clothing should be loose fitting and 100 percent cotton. New clothing should be washed in dye-free, unscented detergent before being worn.
Yoga and other relaxation techniques may help prevent atopic dermatitis caused by stress.
Avoidance of sweating may aid in preventing seborrheic dermatitis.
A person who has dermatitis should also notify a doctor if any of the following occurs:
- fever develops
- skin oozes or other signs of infection appear
- symptoms do not begin to subside after seven days of treatment
- he/she comes into contact with someone who has a wart, cold sore , or other viral skin infection
Allergic reaction —An immune system reaction to a substance in the environment; symptoms include rash, inflammation, sneezing, itchy watery eyes, and runny nose.
Corticosteroids —A group of hormones produced naturally by the adrenal gland or manufactured synthetically. They are often used to treat inflammation. Examples include cortisone and prednisone.
Patch test —A skin test in which different antigens (substances that cause an allergic reaction) are introduced into a patient's skin via a needle prick or scratch and then observed for evidence of an allergic reaction to one or more of them. Also known as a scratch test.
Rash —A spotted, pink or red skin eruption that may be accompanied by itching and is caused by disease, contact with an allergen, food ingestion, or drug reaction.
Ulcer —A site of damage to the skin or mucous membrane that is characterized by the formation of pus, death of tissue, and is frequently accompanied by an inflammatory reaction.
Eating a balanced and adequate diet is generally helpful. People who are susceptible to dermatitis that is linked to particular foods obviously should avoid consuming them.
Parents should try to monitor new substances and foods when their children encounter them for the first time.
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L. Fleming Fallon, Jr., MD, DrPH