Identifying and Treating Contact Dermatitis

What contact dermatitis is

Contact dermatitis is a type of eczema that develops when your skin reacts to something it has touched. The affected area can become red, itchy, dry, cracked or sore. In some cases it may blister, weep or feel as though it is burning.

It is common and usually not serious, although it can be uncomfortable and frustrating. The rash normally appears where the substance touched your skin, so the hands and face are often affected. The good news is that once you work out what is causing it, you can usually prevent it from coming back.

Contact dermatitis is not contagious. You cannot catch it from someone else or pass it on.

The three main types

Knowing which type you have can help you find the cause and decide what to do about it.

Irritant contact dermatitis is the most common form. It happens when a substance damages the outer layer of the skin directly. This is not an allergy, and anyone can develop it with enough exposure. Common irritants include:

  • soaps, detergents and washing up liquid
  • cleaning products, bleach and solvents
  • frequent hand washing or long periods with wet hands
  • wet cement, oils and some industrial chemicals
  • friction, or dry air from heating and air conditioning

Strong irritants can cause a reaction quickly. Milder ones, such as water and soap, tend to cause problems gradually after repeated contact over days or weeks.

Allergic contact dermatitis is caused by the immune system reacting to a particular substance, known as an allergen. The first contact does not usually cause a rash. Instead, your body becomes sensitised, and later exposures trigger a reaction, often 24 to 48 hours afterwards. Once you are allergic to something, this will usually last for life. Common allergens include:

  • nickel, found in some jewellery, watch straps, belt buckles and jeans studs
  • fragrances in toiletries and cosmetics
  • preservatives in creams, shampoos and wet wipes
  • hair dye, particularly a chemical called PPD
  • rubber and latex, including some gloves
  • certain plants, such as primula and chrysanthemums

Photocontact dermatitis is less common. It happens when a substance on the skin only causes a reaction after exposure to sunlight. Some sunscreens, perfumes and plant juices can cause this. The rash usually appears on areas exposed to the sun.

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Finding the cause

Think about where the rash appears and when it started. A rash under a ring or watch strap points towards metal. A rash on the hands that gets worse after cleaning suggests detergents. Rashes on the eyelids or face can be linked to cosmetics, nail varnish or products transferred from the hands.

Your job and hobbies may be relevant too. Hairdressers, cleaners, healthcare workers, builders, mechanics and caterers are among those more likely to develop contact dermatitis. The Health and Safety Executive (HSE) has guidance on work related dermatitis, and employers have duties to help protect staff from skin hazards.

If you cannot pin down the trigger, your GP may refer you to a dermatology clinic for patch testing. This involves placing small amounts of common allergens on your back and checking for reactions over a few days. It can help confirm allergic contact dermatitis but does not test for irritants.

Treating and preventing it

The most effective step is to avoid whatever is causing the reaction. Once you stop contact, the skin will usually start to heal within a few weeks. Other things that can help include:

  • using an emollient (moisturiser) regularly, even when the skin looks clear
  • washing with a soap substitute rather than ordinary soap
  • wearing suitable gloves for cleaning and wet work, ideally with cotton liners
  • drying your hands thoroughly and removing rings before washing
  • checking product labels for ingredients you know you react to

A pharmacist can advise on emollients and may suggest a mild steroid cream, such as hydrocortisone, for a short period to calm inflammation. Some steroid creams are not suitable for the face or for children without medical advice, so always ask first and follow the instructions. Antihistamines are not usually effective for the rash itself but may help if itching is disturbing your sleep.

See your GP if:

  • the rash does not improve after avoiding the likely cause and using emollients
  • it is spreading, severe or affecting your daily life or work
  • you do not know what is triggering it
  • the skin looks infected, for example if it is hot, swollen, painful, crusting or oozing pus

Your GP may prescribe a stronger steroid cream or refer you to a dermatologist. If you feel unwell with a fever alongside an infected rash, or have swelling of the face or lips, contact NHS 111 or seek urgent help.

For more information, the NHS website has pages on contact dermatitis and eczema, and the British Association of Dermatologists publishes patient leaflets on common allergens and patch testing.