Contact dermatitis
Contact dermatitis
What is contact dermatitis?
Dermatitis (also known as eczema) means inflammation of the skin. Contact dermatitis is where the skin reacts to substances it has come to contact to. It is a common condition. It can have a long-term impact on a person’s life, their daily activities, emotional well-being, and social interactions.
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What causes contact dermatitis?
There are two main types of contact dermatitis:
Irritant contact dermatitis
- Irritant contact dermatitis is when the skin comes into contact with irritating substances causing a red, itchy rash. It usually appears within minutes to hours after contact. This condition develops when the skin is repeatedly in contact with these substances for a long time. Examples of substances include cleaning products, laundry detergents, and everyday chemicals.
- The most important factors in causing this type of contact dermatitis are the frequency of exposure to detergents, powders, plants and solvents, and the strength of concentration. The hands are most commonly affected. People in certain occupations where they come into contact with solvents (such as petrol) oils and other chemicals are, therefore, at higher risk. It is more commonly found in people working as:
- beauticians
- cooks
- florists
- hairdressers
- metal working machine operatives
- gardeners
- healthcare practitioners.
- Anyone can develop irritant contact hand dermatitis from handling irritating substances, or with frequent handwashing. It is, however, more common in people who have suffered from types of dermatitis in the past, such as eczema.
Allergic contact dermatitis
- Allergic contact dermatitis occurs when the immune system reacts against a specific substance. The substance is then called an allergen. Symptoms usually appear within hours or days after contact. Once the skin becomes sensitive to certain allergens inflammation will happen when it comes into further contact. Common causes of allergic contact dermatitis include
- Personal care products such as cosmetics, skincare products, preservatives, nail varnish, fragrances, sunscreen and hair dye.
- Metals in some jewellery, such as nickel and cobalt, can also cause reactions.
- Chromate, which is a metal found in cement.
It is unclear why some people develop an allergic reaction while others do not, but it is not linked to having eczema during childhood.
Certain proteins can also cause an immediate allergic reaction on the hands when touched. These proteins may be found in raw fruits and vegetables, such as uncooked potatoes, for example. The reaction causes itchy skin and swelling known as contact urticaria (commonly known as hives).
In people with existing hand dermatitis, it can also cause, small blisters, scaling, itching and redness. In people with darker skin, it can show as darker skin patches. This is known as protein contact dermatitis and it affects mostly food handlers.
Contact dermatitis is not contagious and cannot spread from person to person. However, a bacterial infection of contact dermatitis may lead to a condition called impetigo. Impetigo is very contagious and needs treatment from your healthcare provider.
Is contact dermatitis hereditary?
Irritant contact dermatitis can run in families. This is because people with hereditary conditions like asthma, eczema or hayfever are more likely to develop it.
However, allergic contact dermatitis is not typically passed down from parents.
What does contact dermatitis feel and look like?
Allergic contact dermatitis and irritant contact dermatitis can feel and look similar, but there are some distinct differences.
Allergic contact dermatitis usually starts as an itchy rash that looks red inflamed and blistered. The affected skin can peel and look red and oozy. I In richly pigmented skin (such as brown or black), the skin can look purple, deep brown or greyish.
- In irritant contact dermatitis, skin changes include burning, stinging, soreness and discomfort. The skin can swell and develop blisters. Irritant contact dermatitis can appear red in less pigmented skin; it can be less visible in brown in black or brown skin.
Contact dermatitis of the hands may reduce hand function due to the development of painful splitting and cracking of the skin.
Whilst contact dermatitis most commonly affects the hands, it may affect other areas of skin such as the arms, neck and face. The affected skin may become bumpy, blistered, swollen, scaly and oozing. It can also appear red or darker than usual, depending on the skin tone. For example, in darker skin, such as brown or black, the affected skin may appear darker than the surrounding skin; in white skin tones, the affected skin may be red.
With repeated exposure to irritants over time, the skin can look thickened and leathery with skin splits or tears. This can be painful and sore.
How will contact dermatitis be diagnosed?
Irritant contact dermatitis
The doctor may suspect irritant contact dermatitis based on a person’s exposure to irritating substances, considering their job, lifestyle and hobbies. The rash in a specific area of the body with typical features of dermatitis will help confirm the diagnosis.
Allergic contact dermatitis
The doctor may suspect allergic contact dermatitis based on a person’s history. A test called patch testing is required to identify the exact cause. Patch testing is carried out in a specialist dermatology department. The test involves placing patches containing common allergens on the patient’s back. The patches are removed after 2 days, and the tested skin is examined immediately and again after a further 2 days. If a small rash appears, it is known as a ‘positive patch test’. The dermatologist then advises the patient which contact allergens to avoid. Patch testing is usually performed when the cause is unknown, or when the rash is unresponsive to topical treatment (such as creams, gels, ointment).
Can contact dermatitis be cured?
There is no cure for contact dermatitis. However, the condition can be prevented and managed by identifying and avoiding substances that are triggers. In some cases, this may mean changing jobs – for example, if a hairdresser is allergic to hair dyes, a nail beautician who is allergic to nail cosmetics (acrylates), or builders using cement.
If patch testing confirms an allergy to a specific substance, avoiding it can lead to a significant improvement or even complete clearance of allergic contact dermatitis. Continued contact with the triggering substance will make the skin condition worse.
How can contact dermatitis be treated?
The main way of treating contact dermatitis and to stop it from coming back is to find the causes and avoid them. It may take several months for contact dermatitis to settle.
Completely avoiding some triggers may be challenging as they are commonly found in our everyday lives. Therefore, protecting the skin is important. For example, wearing gloves can protect the hands from direct contact with triggers.
Moisturisers, emollients and soap substitutes
Regular use of moisturisers (also called emollients) can help improve the skin barrier and hydration. It may also be necessary to completely avoid contact with soaps and detergents. (For more information on protecting the hands see our leaflets on hand dermatitis and how to care for your hands).
Moisturisers and soap substitutes may be used to improve the barrier function of the skin and maintain skin hydration.
Keeping the skin moisturised (hydrated) is very important. Use an emollient several times a day:
- Thick emollients are best for the hands and other affected areas in the evenings.
- Lighter or gel-based moisturisers should be used very frequently during the day.
It is important to find moisturisers that you like as they will be used very frequently. For sudden flare ups of contact dermatitis, cool compresses or oatmeal baths may help soothe the skin.
If contact dermatitis is very severe, keeps coming back or covers a large area of skin, your GP or nurse can refer you to a dermatologist (a skin doctor).
CAUTION: This leaflet mentions ‘emollients’ (moisturisers). Emollients, creams, lotions and ointments contain oils. When emollient products get in contact with dressings, clothing, bed linen or hair, there is a danger that they could catch fire more easily. There is still a risk if the emollient products have dried. People using skincare or haircare products should be very careful near naked flames or lit cigarettes. Wash clothing daily and bedlinen frequently, if they are in contact with emollients. This may not remove the risk completely, even at high temperatures. Caution is still needed. More information may be obtained here.
Steroids
Sometimes moisturises are not enough to calm the irritated skin. In these cases, your healthcare professional may recommend a topical steroid cream or ointment also called topical corticosteroid. Topical calcineurin inhibitors, such as tacrolimus ointment or pimecrolimus cream, can also be used as a steroid-free option.
Topical treatments are applied directly to the affected skin. They help to reduce the inflammation in the skin (redness, swelling) and come in different strengths. It is important to use the right strength for the right amount of time, as advised by a healthcare professional.
Oral treatments
In some cases, additional treatments, taken orally (by mouth) may be necessary. These can include steroid tablets and oral antibiotics. Rarely, more specialised medicines, such as ciclosporin or methotrexate may be needed. Ciclosporin and methotrexate are medications that work by suppressing the immune system which hence reduces skin inflammation. These are usually prescribed by a dermatologist in the hospital.
What can I do?
- If you think you have contact dermatitis, use the information provided above to protect your skin. Wear gloves when needed and avoid direct contact with soaps, detergents and allergens as much as possible. You can also see your GP or nurse about contact dermatitis, especially if you do not know the cause of the irritation.
- Keep your skin healthy, by using gentle, non-perfumed moisturisers several times a day. At night, a thicken and more greasy ointment can help keep your skin soft.
- Avoid anything that may be causing skin irritation or allergic reaction.
- Take good care of your skin, both at home and at work (or school), and follow your doctor’s advice on the correct use of various creams and treatments.
Images DermNetNZ.