Contact Dermatitis

contact dermatitis

Contact dermatitis is a rash caused by your skin reacting to a substance it has come into contact with.

What is 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. Various parts of the skin tend to flare up with inflammation from time to time.

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. This is common and causes .It most commonly affects the hands. Irritant substances are those that can cause inflammation in almost everyone if they are in contact for long enough. For example:

Detergents , soaps, bleach. People who do a lot of cleaning are prone to irritant contact dermatitis.
Solvents (such as petrol), oils and other chemicals used in various places of work.
Acids and alkalis, including cement.
Powders, dust and soil.

You can develop irritant contact dermatitis quickly from a single exposure to a strong irritant or due to repeated exposures to weaker irritants. There is often a vicious circle. A patch of skin may become sore after being in contact with an irritating substance causing some skin damage. Damaged skin is more easily affected by irritants. So, further contact, even with small amounts of the substance, cause further inflammation and damage and so on.

  • 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 .Once sensitized, your skin reacts and becomes inflamed when it comes into further contact with the allergen. It is not clear why some people become allergic to some substances and most people do not.

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.
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.
Plants - the most common culprits being chrysanthemums, sunflowers, daffodils, tulips and primula.
Sometimes the cause is not clear and you may need tests to find the cause (see below).

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. Strong irritants can produce immediate reactions, whereas mild irritants require longer or repeated exposure to cause a reaction. The symptoms only occur on areas of skin exposed to 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. For example, eyelids and cheeks if the allergy is to a cosmetic. However, as it is a true allergy, other areas of skin that were not in direct contact with the allergen may develop a rash.

Can you have different types of dermatitis at the same time?

Yes. For example, you may be born with atopic eczema. Your job may involve frequent use of a solvent which may cause an irritant contact dermatitis. In addition, you may also develop an allergy to nickel and so find that you get patches of inflammation over jean studs, or if you wear cheap jewellery, etc.

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. Or, it may be a substance which is an additive to various things and you cannot pinpoint what it is. 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.

If no skin reaction occurs on patch testing then this can also be helpful to rule out allergic contact dermatitis as a cause of your skin problem.

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. Soap substitutes may also be suggested.
Topical steroids
Topical steroids are creams, ointments and lotions which contain steroid medicines.
You should wait for several minutes after you have used an emollient (moisturiser) before you apply a steroid cream. Short courses of topical steroids (less than four weeks) are usually safe and usually cause no problems. Side-effects may develop if topical steroids are used for long periods, or if short courses are repeated often. The main concern is if strong steroids are used on a long-term basis.

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?

Once the inflammation has settled, the main aim is to prevent it from happening again.

Avoid the cause
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
Topical steroids will ease a flare-up of symptoms but are not a long-term cure for contact dermatitis. The only long-term cure is to identify the cause and to avoid it.


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