Dermatitis

Author: Dr Amanda Oakley, Dermatologist, Hamilton, New Zealand,1997.


What is dermatitis?

Dermatitis refers to a group of inflammatory conditions. It affects the outer layer of the skin, the epidermis

Dermatitis affects about one in every five people at some time in their lives. It results from a variety of different causes and has various patterns.

The terms dermatitis and eczema are often used interchangeably. In some cases the term eczematous dermatitis is used. Dermatitis can be acute or chronic or both.

  • Acute eczema (or dermatitis) refers to a rapidly evolving red rash which may be blistered and swollen.
  • Chronic eczema (or dermatitis) refers to a longstanding irritable area. It is often darker than the surrounding skin, thickened (lichenified) and much scratched.

An in-between state is known as subacute eczema.

Psychological stresses can provoke or aggravate dermatitis, presumably by suppressing normal immune mechanisms.

Some types of dermatitis

  • Atopic dermatitis is particularly prevalent in children; inherited factors seem important, as there is nearly always a family history of dermatitis or asthma.
  • Irritant contact dermatitis is provoked by handling water, detergents, solvents or harsh chemicals, and by friction. Irritants cause more trouble in those who have a tendency to atopic dermatitis.
  • Allergic contact dermatitis is due to skin contact with substances that most people don't react to: most commonly nickel, perfume, rubber, hair dye or preservatives. A dermatologist my identify the responsible agent by patch testing.
  • Dry skin: especially on the lower legs, may cause asteatotic dermatitis, also called eczema craquele.
  • Nummular dermatitis (also called 'discoid eczema') may be set off initially by an injury to the skin: scattered coin-shaped irritable patches persist for a few months.
  • Seborrhoeic dermatitis and dandruff are due to irritation from toxic substances produced by malassezia yeasts that live on the scalp, face and sometimes elsewhere.
  • Infective dermatitis seems to be provoked by impetigo (bacterial infection) or fungal infection.
  • Gravitational dermatitis arises on the lower legs of the elderly, due to swelling and poorly functioning leg veins.
  • Otitis externadermatitis affecting the external ear canal
  • Meyerson naevusdermatitis affecting melanocytic naevi (moles)
Dermatitis

Treatment of dermatitis

An important aspect of treatment is to identify and tackle any contributing factors (see above).

  • Bathing Reduce how often you bath or shower, using lukewarm water. Showers are better. Replace standard soap with a substitute such as a mild detergent soap-free cleanser: your chemist or dermatologist can advise you.
  • Clothing Wear soft smooth cool clothes; coarse fibres (wool or synthetic) are best avoided (microfine merino wool may be suitable)
  • Irritants Protect your skin from dust, water, solvents, detergents, injury.
  • Emollients Apply an emollient liberally and often, particularly after bathing, and when itchy. Ask your doctor or dermatologist to recommend some to try; avoid perfumed products when possible.
  • Topical steroids Apply a topical steroid cream or ointment to the itchy patches for a 5 to 15 day course. A suitable one will be prescribed by your doctor or dermatologist. Make sure you understand when and where to apply it, and how often you may repeat the course. Steroids should usually be applied once or twice daily to the red and itchy areas only. Sometimes two or more topical steroids will be supplied, either for different parts of the body, or for differing grades of dermatitis.
  • Pimecrolimus cream Pimecrolimus is a new anti-inflammatory cream shown to be very effective for atopic dermatitis, with fewer side effects than topical steroids.
  • Antibiotics Your doctor will recommend antibiotics such as flucloxacillin or erythromycin if infection is complicating or causing the dermatitis. The infection is most often with Staphylococcus aureus or Streptococcus pyogenes.
  • Antihistamines Antihistamine tablets may help reduce the irritation, and are particularly useful at night.
  • Other treatments Systemic steroids, methotrexate, azathioprine, ciclosporin, mycophenolate, phototherapy, and other complicated treatments may also be used for severe cases.

Long term control

Dermatitis is often a long-term problem. When you notice your skin getting dry, moisturise your skin again and carefully avoid the use of soap. If the itchy rash returns, use both the moisturiser and the steroid cream or ointment. If it fails to improve within two weeks, see your doctor for further advice.

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