What is contact dermatitis?
Contact dermatitis is an inflammation of the skin triggered by a substance the skin has come into contact with. The substance may be an allergen – something that provokes an allergic reaction – or an irritant – something that damages the skin. Inflammation commonly results in red, itchy and cracked skin.
Contact dermatitis is a common condition that is more likely to affect people who work with their hands, such as healthcare workers, hairdressers and some factory workers, especially when the work exposes the skin to possible irritants. It is generally a non-serious condition that will clear up with treatment.
Causes of contact dermatitis
There are two types of contact dermatitis: irritant contact dermatitis and allergic contact dermatitis. Of these, irritant contact dermatitis is the most common, accounting for roughly 80 percent of all cases.
Irritant contact dermatitis occurs when the skin comes into contact with a substance that irritates the skin. Irritants come in many forms, and may include:
- Prolonged exposure to water can cause skin irritation, especially if the water contains chlorine or is hard or chalky
- Detergents, such as washing-up liquid, soap or bleach
- Solvents, such as oil, petrol or chemicals found in the workplace
- Acids and alkalis
- Dust, soil and powders
- Certain plants, such as clematis, hellebore and poison ivy
The condition may develop following a single exposure to a very strong irritant, or develop from frequent exposure to a weaker irritant.
Allergic contact dermatitis occurs when the skin comes into contact with a specific substance which triggers an allergic reaction, known as an allergen. The allergen can be something the skin has newly been exposed to or something it has been exposed to many times before. Why some people develop allergic contact dermatitis and some do not is not entirely clear.
A wide array of substances can cause an allergic reaction, though some of the most common include:
- Nickel, a substance common in metal alloys used in everyday items such as jewellery, clothes and bra straps
- Cobalt, a metal sometimes found in jewellery
- Chromate, a metal sometimes found in cement
- Cosmetics, such as perfumes, hair dyes and nail varnish
Symptoms of contact dermatitis
The symptoms of contact dermatitis occur on the part of the skin that has come into contact with the cause of the irritation. This is often the hands, face or areas of skin that have contact with clothing or jewellery.
Typical symptoms of contact dermatitis include:
- Itchy skin
- A red, blotchy rash
- Dry and scaly skin
- Fluid-filled blisters
Diagnosing contact dermatitis
Irritant contact dermatitis is diagnosed according to the person’s history of exposure to irritants and through an inspection of the symptomatic area of the skin.
To diagnose allergic contact dermatitis, in addition to an examination of the affected area, a patch test will be carried out. This involves applying small patches containing common allergens to the skin, typically on the back, leaving them for a set amount of time – normally around two days – and then inspecting the results for signs of dermatitis. Following this, the dermatologist will be able to identify which allergen is responsible for the reaction.
Contact dermatitis treatment
Treating contact dermatitis will typically involve moisturizers, topical corticosteroids and/or steroid tablets. A dermatologist will be able to advise on the best course of treatment for each person.
Moisturizers are often useful in the treatment of dry and scaly skin. A variety of different emollients are available – a dermatologist will be able to offer advice on which type is most suitable.
Topical corticosteroids are steroid-containing creams and ointments that are applied directly to the affected skin. They can be effective in treating the redness and pain of dermatitis. Topical corticosteroids are available in a range of strengths, with the appropriate strength dependent on the severity and location of the dermatitis.
In severe cases, particularly when the dermatitis covers a large area of skin, steroid tablets may be prescribed. Always follow the instructions provided by the doctor when taking this kind of medication.
In mild cases, home remedies such as cool baths or cool, wet compresses may be effective in soothing the symptoms of contact dermatitis.
Contact dermatitis prevention
Avoiding contact with the irritant or allergen that is causing contact dermatitis is the most effective way of preventing the condition. If total avoidance is not possible, creating a barrier between the substance and the skin – by wearing gloves, for example – is recommended. Carrying out a patch test before using new cosmetics or detergents, and using barrier creams may also help to prevent the onset of contact dermatitis.
Other names for contact dermatitis
- Contact eczema
UpToDate. “Patient education: Contact dermatitis (including latex dermatitis) (Beyond the Basics).” November 27, 2017. Accessed June 21, 2018. ↩ ↩ ↩