Dermatitis is a skin inflammation that causes red, itchy, crusted skin that can become swollen or blistered. Dermatitis affects about 20% of people at some time.
Most dermatitis falls into one of the two following categories:
- Atopic dermatitis – some children are born with a tendency to develop this ongoing (chronic) form of dermatitis. Atopic dermatitis is commonly known as eczema.
- Contact dermatitis – people with allergies can react to particular substances from time to time, while others can be sensitive to irritants; these are both forms of contact dermatitis.
Atopic dermatitis (eczema)
Atopic dermatitis (also known as eczema) tends to affect the face and skin creases of about 15% of infants and young children. The affected areas (e.g: behind the knee, inside the elbow) tend to be very dry and itchy. Scratching is a common problem – it can lead to further itchiness, broken skin and skin infections.
Atopic dermatitis is often made worse by:
- hot conditions (such as warm weather and hot baths)
- soaps and perfumes
- woollen clothing
- dust or pets.
The cause is unknown and there is no permanent cure. However, it can usually be controlled with appropriate advice and treatment. It generally improves with time. Most children grow out of it but it can recur, particularly if the skin is exposed to irritants later in life.
This form of dermatitis is often caused by repeated contact with detergents, skin cleansers, acids or alkalis, solvents or other products. Such contact eventually dries the skin and breaks down its protective layers. Irritant contact dermatitis usually affects the hands.
Certain occupations which involve exposure to irritants as an everyday part of the job can make people more prone to this type of dermatitis. Irritant contact dermatitis is particularly high amongst nurses and hairdressers (soaps, hot water, shampoos), builders and cleaners (solvents) and motor mechanics. People who work in these types of jobs and who have had atopic dermatitis should also be aware of the risk of flare-ups.
This form of contact dermatitis is much less common. It affects people who become over-sensitised (allergic) to contact – even very occasionally – with certain everyday substances. This differs from irritant contact dermatitis where regular contact with a range of irritants is the problem.
When you touch a substance you are allergic to, your body's immune system reacts to form a rash at the point of contact (usually the hands). This rash may spread, making it difficult to know where it started and what caused it. Only substances you have an allergy to will cause this. Allergies to nickel in jewellery, latex in rubber gloves, clothing elastic, medical strapping and plasters are quite common.
Causes of dermatitis include:
- inherited factors – family members with dermatitis/eczema, asthma or hay fever
- irritants – eg, detergents, solvents, soaps, scented household fragrances
- substance casing allergy – eg, nickel (in jewellery), latex rubber, plants
- intolerance / allergy to certain foods – eg, cow's milk, wheat (gluten)
- dry skin
- skin infection or injury.
The cause of a rash or scaly patch may not be obvious, so letting your doctor make a proper diagnosis is the first step. You may need to try a cream or medication, have a skin test for allergies or have skin or nail scrapings taken to test for other (secondary) infections.
Ways to treat dermatitis include:
- Irritant avoidance – protect your skin from detergents, chemicals, dust and water.
- Gentle cleaning – shower rather than take baths, in lukewarm not hot water, use a soap-free cleanser and pat yourself dry rather than rub.
- Moisturisers/emollients – apply liberally and frequently (at least daily).
- Topical corticosteroids – apply to red, itchy patches only. Different strengths may have to be used for different areas. A course is usually two weeks or less.
- Pimecrolimus cream – a non-steroid cream used in specific situations where corticosteroids are not working or are inappropriate.
- Antibiotics – may be needed if infection is also present.
- Antihistamine tablets – may help reduce itching.
Hydrocortisone is a weak corticosteroid. There are many stronger ones that require much more care. You may be given more than one cream. If so, make sure you understand how to use each one, and:
- use according to a doctor or pharmacist’s advice
- apply only where recommended (and not to broken skin)
- use sparingly – overuse can cause the skin to thin
- use carefully in children or if applied to the face.
Ask for specific instructions on how to use your topical steroid(s): which one? where? when? how often, and for how long?
Looking after your skin
By carefully avoiding irritants and substances causing allergy, looking after your overall health, taking medications as advised by your doctor and products to keep your skin moist (moisturisers), soft and supple (emollients), you can help improve and protect your skin.
Living with dermatitis
Dermatitis is often a long term problem. If your skin tends to be dry, try to avoid excessive bathing and soaps (they are alkaline and the perfumes in them can irritate your skin). Soap substitutes (eg, aqueous cream) can be used instead, and adding oatmeal or tar-based pine oil products to your bathwater may relieve itchy skin.
Emollients or moisturisers are an important core treatment as they help maintain the skin’s protective barrier function (keeping moisture in and irritants out). They also prevent dry skin and the inflammation that can lead to a flare up of the rash.
- Dry skin is itchy skin. Apply emollients liberally and frequently, ideally after bathing/showering within a few minutes of patting skin dry. Your doctor can prescribe emollients on prescription to cost you less.
- When your skin is clear, use emollients to keep skin healthy.
- If the itchy rash returns, continue the emollient and use the corticosteroid or non-steroid cream or ointment advised by your doctor.
- Antihistamine tablets may help relieve itching, especially at night.
- If the rash does not improve within two weeks, seek help from your doctor. It is also important to see your doctor if your rash looks infected (weepy, crusted, pustules, no improvement with treatment, or you feel unwell).
For allergic dermatitis, finding the substance causing the allergy and avoiding it is the only real cure. Your doctor can arrange for you to have specific allergy tests if the substance causing it is not obvious.
If your dermatitis is caused by household or workplace irritants, you may not be able to avoid them. Using barrier creams or gloves may help protect your skin.
Dermatitis DermNet New Zealand
Eczema Allergy New Zealand
Source: Health Navigator