Contact Dermatitis

contact dermatitis

Dermatitis means inflammation of the skin. Dermatitis is also called eczema. It causes red, itchy skin which may also blister. There are several types of dermatitis. However, dermatitis is generally grouped into two main types:
Dermatitis caused by a problem from within the body. For example, atopic eczema (atopic dermatitis) is a common condition which tends to run in families. If you have atopic eczema you are born with a tendency for your skin to become inflamed.

Dermatitis caused by a substance from outside the body. This typically causes patches of inflammation on areas of skin which have come into contact with the substance. This is called contact dermatitis. If you avoid the offending substance, the skin inflammation should go away.

Types of contact dermatitis

There are two types of contact dermatitis - irritant and allergic.

Irritant contact dermatitis

This is caused by direct contact with a substance which irritates the skin. For example:

  • Detergents (washing-up liquid, soaps, bleach, etc).
  • Solvents (such as petrol), oils and other chemicals used in various places of work.
  • Acids and alkalis, including cement.
  • Powders, dust and soil.
  • Certain plants

Allergic contact dermatitis

This occurs when your immune system reacts against a specific substance. The substance is then called an allergen. You only need a small amount of allergen in contact with your skin to cause the rash.

Many substances can cause an allergic contact dermatitis. Common ones include:

  • Nickel - this is the most common cause. Nickel occurs in many types of metal. For example: jewellery, studs in jeans and other clothes, bra straps, etc. So it is common to develop itchy red patches on the skin next to such things.
  • Cobalt - traces of this metal may be found in some jewellery.
  • Cosmetics - particularly perfumes, hair dyes, preservatives and nail varnish resins.
  • Additives to leather and rubber (in shoes, clothes, etc).
  • Preservatives in creams and ointments.

What are the symptoms of contact dermatitis?

Irritant contact dermatitis

The main symptoms are redness, burning, stinging and soreness of affected areas of skin. The onset of the skin reaction is usually within 48 hours of coming into contact with the irritant.

Allergic contact dermatitis

The main symptoms are redness, itch and scaling of affected areas of skin. There is often a delay of many hours to several days before symptoms develop following contact with the allergen (the sensitising object or chemical). The site of the rash and skin symptoms is mainly where the contact had been.

Do I need any tests?

The cure for most cases of contact dermatitis is to avoid the offending substance. In many cases no tests are needed, as it is often clear which substance has caused the rash. However, sometimes it is not clear what is causing the rash. This is where patch testing may be advised.

Patch testing

Patch testing helps to find the cause of allergic contact dermatitis. You need to be referred to a dermatologist (skin specialist) for patch testing. They will place a small amount of various substances that may be causing the rash on to your skin. This is usually done on the skin of your back, in sets of 10. The skin is then covered with an adhesive dressing.
After two days the dressing is removed and the skin is examined to see if there is a reaction to any of the tested substances. The skin is also usually examined again after a further two days in case you have a delayed reaction to any substance. Sometimes the skin may be examined again a week after the initial substances were put on your skin.

What is the initial treatment for contact dermatitis?

As mentioned, the main treatment is to avoid the offending substance. However, your skin may also be sore, itchy and scaly so various initial treatments may be suggested to help clear your symptoms.

Emollients (moisturisers)

If the inflamed skin is not too bad then just using an emollient (moisturiser) frequently may be all that you need until the inflammation settles and the rash clears.

Topical steroids

Topical steroids are creams, ointments and lotions which contain steroid medicines. They work by reducing inflammation in the skin.

Other treatments

An antibiotic may be prescribed if the inflammation becomes infected. This is uncommon in most bouts of contact dermatitis. Rarely, a course of steroid tablets is needed if you have a large and severe area of skin inflammation.
Rarely, steroid treatment does not clear contact dermatitis and other treatments may be suggested. These may include tacrolimus cream and treatment with medicines such as azathioprine, ciclosporin or oral retinoids. Ultraviolet (UV) light exposure, sometimes helped by taking a medicine called psoralen, is also sometimes recommended. This is known as psoralen combined with ultraviolet A (UVA) treatment (PUVA). Grenz rays (low-energy electromagnetic rays) are sometimes used when other treatments fail.

What is the long-term treatment for contact dermatitis?

Avoid the cause

Hand care

  • Don't keep your hands in water for very long.
  • Use protective gloves wherever possible when working with chemicals, detergents, etc.
  • Consider using a barrier cream to help protect the skin on your hands when working.
  • Use a mild skin cleanser rather than soap to clean your hands.
  • Dry your hands thoroughly after washing.
  • Use lots of moisturising cream and apply it frequently. This helps to keep the skin on your hands supple and to prevent chapping.
  • Intermittent use of topical steroid

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