Contact dermatitis

Contact dermatitis is inflammation of the skin that occurs when you come into contact with a particular substance. It can cause red, itchy and scaly skin, and sometimes burning and stinging.

Contact dermatitis is a type of eczema. This is the name for a group of skin conditions that cause dry, irritated skin. There are several other types of eczema, including:

  • atopic eczema (also called atopic dermatitis), which often runs in families and is linked to other conditions, such as asthma and hay fever
  • discoid eczema, which usually affects adults and causes circular or oval patches of eczema 
  • varicose eczema, which occurs on the legs, usually around varicose veins (swollen and enlarged veins)

Types of contact dermatitis

There are two types of contact dermatitis:

  • allergic contact dermatitis - this is caused by an allergen (a substance that causes an immune response in the skin)  
  • irritant contact dermatitis - this is caused by an irritant (a substance that damages the skin physically)

Allergic contact dermatitis involves the immune system, the body's natural defence system, which reacts abnormally to the allergen. The first time this happens, the body becomes 'sensitised' to the allergen. The next time you come into contact with the allergen, the body 'remembers' the previous exposure and it causes a reaction.

Irritant contact dermatitis can occur in anyone who is exposed to irritants for a sufficient amount of time.

Both types of contact dermatitis can cause your skin to become red, blistered, dry and cracked. Sometimes, it is possible to have both irritant and allergic contact dermatitis at the same time.

How common is contact dermatitis?

Irritant contact dermatitis is more common than allergic contact dermatitis. Irritants cause up to 8 out of 10 cases of contact dermatitis.

Three-quarters of all contact dermatitis cases affect the hands. It is also more common in women, with approximately 1 in 5 women experiencing contact dermatitis on their hands at some point during their lives. This may be because women are exposed to more environmental factors that cause contact dermatitis.

Contact dermatitis can develop at any age and can affect anybody.

Outlook

Treatment for contact dermatitis involves using emollients to soothe the skin. An emollient is a moisturiser applied to the skin to reduce the loss of water from the skin. Corticosteroid medicines can be used to treat severe symptoms.

With treatment, most people with contact dermatitis can expect their symptoms to improve at least partially. In up to two out of five people, the condition will clear up completely.

Another part of treating contact dermatitis involves avoiding the allergens or irritants that cause it. If you can successfully avoid the allergens or irritants, your condition will clear up.

Both allergic and irritant contact dermatitis can cause your skin to become:

  • red
  • inflamed
  • blistered
  • dry
  • thickened
  • cracked

The most commonly affected areas of skin are your hands and face. Depending on the type of contact dermatitis you have, you may also experience other symptoms.

Allergic contact dermatitis

As well as the symptoms listed above, allergic contact dermatitis will cause the skin to be itchy. It may take many hours or several days for your symptoms to appear after you come into contact with the allergen.

In most cases, the area of skin that had contact with the allergen will be the area that is affected. For example, if you are allergic to an eye shadow or blusher, your eyelids or cheeks may be affected. However, sometimes other areas of skin may also be affected, even if they did not come into contact with the allergen.

Irritant contact dermatitis

As well as the symptoms listed above, irritant contact dermatitis causes burning, stinging and soreness. Your symptoms will usually appear within 48 hours of coming into contact with the irritant.

Strong irritants may cause your skin to react immediately, although you may need to come into contact with some common irritants, such as soap and detergents, frequently and repeatedly before they cause problems.

Irritant contact dermatitis will only affect the areas of skin that have been exposed to the irritant.

Allergic contact dermatitis
This is caused by an allergen (a substance that causes an immune response in the skin).

Irritant contact dermatitis
This is caused by an irritant (a substance that damages the skin physically).

Inflammation
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.

Contact dermatitis occurs when your skin reacts to a particular substance, which can be:

  • an allergen - a substance that can cause the body to react abnormally
  • an irritant - a substance that damages the skin

Allergic contact dermatitis

Allergic contact dermatitis occurs when you come into contact with an allergen that your body becomes sensitised to. When you touch that substance again, your skin reacts with an itchy red rash (dermatitis).

You develop a rash because your immune system reacts abnormally to the allergen. Your immune system is the body's natural defence system that usually protects your body against infection and illness. During an allergic reaction, the immune system can attack healthy cells and tissue as well. This is what causes your skin to be sore and inflamed (red and swollen).

Common allergens that can cause allergic contact dermatitis include:

  • metals, such as nickel or cobalt in jewellery
  • cosmetics, such as fragrances, hair dye and nail varnish
  • preservatives, which are added to prevent germs growing inside a medicine - preservatives are often found in medicines that are available over the counter and in some prescribed creams
  • rubber, including latex, a type of naturally occurring rubber 
  • textiles, particularly the dyes and resins that are contained in them
  • strong adhesives (glue), such as epoxy resin adhesives
  • some plants, such as chrysanthemums, daffodils, tulips and primula
  • some topical medicines (medicines that are applied directly to the skin), such as topical corticosteroids and topical antibiotics

Irritant contact dermatitis

Irritant contact dermatitis occurs when your body comes into contact with an irritant. Your skin is damaged by the irritant, which causes a burning and stinging sensation as well as reddening and soreness.

Your irritant contact dermatitis may be caused by frequent exposure to a weak irritant, or it may occur after a single period of exposure to a stronger irritant.

Irritant contact dermatitis can occur in anybody who is exposed to irritants for a sufficient amount of time. You may be at increased risk of irritant contact dermatitis if you have atopic eczema, which is the most common form of eczema and is often inherited from your parents. 

Common irritants include:

  • detergents and soaps
  • perfumes and preservatives in toiletries or cosmetics
  • solvents and abrasives (materials used to grind or polish something)
  • oils used in machines 
  • some chemicals, such as disinfectants 
  • acids and alkalis
  • cement
  • powders
  • water, especially hard, chalky water or heavily chlorinated water
  • dust
  • soil
  • some plants, such as anemone, clematis, ranunculus, helleboros and mustards

Occupational irritant dermatitis

If you work with irritants as part of your job, you may be more at risk of developing irritant contact dermatitis. If you do develop the condition because of a substance you work with, it may be called occupational irritant dermatitis.

This type of dermatitis is more common in certain occupations, including:

  • cleaning and housekeeping
  • food preparation and catering
  • hairdressing
  • agriculture and fishing
  • engineering and construction
  • healthcare (including dentists and vets) 
  • printing and painting

Other contributing factors

If you already have contact dermatitis symptoms, several other factors can make your symptoms worse. These include:

  • heat
  • cold
  • friction (rubbing against the allergen or irritant) 
  • low humidity (dry air)

You are more at risk from these factors if you have irritant contact dermatitis than if you have allergic contact dermatitis.

Your GP will normally be able to diagnose contact dermatitis from the appearance of your skin and by asking about your symptoms. For example, your GP may ask when your symptoms first appeared and what substances you have been in contact with.

Identifying allergens and irritants

If your GP has diagnosed you with contact dermatitis, they will try to identify the allergens or irritants that trigger your symptoms. If the allergens or irritants can be identified, you can take steps to avoid those substances and reduce the risk of your symptoms flaring up.

Your GP will take a detailed look at your medical history, and will also ask questions about your lifestyle and occupation to see what factors may be causing your symptoms. They will also ask you whether there is a history of contact dermatitis in your family.

Referral

If you and your GP cannot identify the allergens or irritants that cause your contact dermatitis, you may be referred for further testing with a dermatologist (a doctor who specialises in treating skin conditions).

You may also be referred to a dermatologist if the allergens or irritants have been identified, but your symptoms are not responding to treatment.

Patch testing

The main way to test for a reaction to allergens is to use patch testing. During a patch test, tiny amounts of suspected substances are applied to your skin. The substances are attached to your back using a special kind of non-allergic tape. Sometimes, they are attached to the upper arm instead.  

After two to four days, the patches are removed and your skin can be assessed to check if there has been any reaction. Your skin will usually also be examined after four to six days as many reactions will take this long to develop.

Photopatch testing

Photopatch testing is a way to diagnose allergic contact dermatitis that only occurs when a particular substance on your skin is exposed to sunlight. This is called photoallergic dermatitis.

In photopatch testing, the allergen is applied to the skin on your upper back as explained above. After two days, the patches are removed and the area is exposed to beams of ultraviolet light (similar to a tanning lamp). Two days later, your skin will be assessed to see whether there has been a reaction.

Open patch testing

Open patch testing is used to assess suspected contact allergens that are potential irritants. In an open patch test, the substance is applied to the skin on your forearm, outer upper arm or shoulder. It is left uncovered and will be checked regularly for up to an hour. Your skin will also be assessed after three or four days. 

In some cases, a repeated open application test may be used, for example to assess cosmetics. This involves reapplying the substance onto the same patch twice a day for up to a week to see how your skin reacts.

Allergen
An allergen is a substance that reacts with the body's immune system and causes an allergic reaction.

Irritant
An irritant is a substance that damages the skin physically.

The symptoms of contact dermatitis can be effectively managed with treatment. Some people's symptoms improve, whereas others find their symptoms clear up entirely. Up to 8 out of 10 people will experience at least a partial improvement in their symptoms after treatment.

There are several ways to treat contact dermatitis, including:

  • avoiding the cause
  • emollients 
  • topical corticosteroids (for severe symptoms) 
  • oral corticosteroids (for widespread severe symptoms) 
  • antibiotics (for infections)

These treatments are explained below.

Avoiding the cause

One of the most important steps in treating contact dermatitis is identifying and avoiding the allergens or irritants that cause it. If you can successfully avoid the cause, you should not experience any symptoms.

It is not always easy to avoid the allergens or irritants that affect you. Your GP or dermatologist (a specialist in treating skin conditions) will help you find ways to minimise your contact with them.

If you are exposed to irritants as part of your job, wear adequate protective clothing to minimise any contact with the irritants. Tell your employer about your condition so they can help you avoid the causes as effectively as possible.

Diet

The allergen nickel causes some cases of contact dermatitis. This is a trace element found in foods such as lentils, nuts and oats. There is some evidence that people who are sensitive to nickel might benefit from following a diet that is low in nickel.

However, evidence to support the benefit of this is very limited and you should speak to your GP before making any changes to your diet.

Emollients

Emollients are substances that help soften and smooth your skin to keep it supple and moist.

As contact dermatitis can cause your skin to be dry and cracked, it is important to keep it moisturised to prevent it from becoming further irritated. Emollients prevent water being lost from the outer layer of the skin and add water to the skin. They act as a protective barrier to keep the moisture in and the irritants out.

Choice of emollient

Several different emollients are available. You may need to try several to find one that works for you. You may also be prescribed a mix of emollients, such as:

  • an ointment for very dry skin
  • a cream or lotion for less dry skin
  • an emollient to use on your face and hands 
  • a different emollient to use on your body  
  • an emollient to use instead of soap 
  • an emollient to add to bath water or use in the shower

The difference between lotions, creams and ointments is the amount of oil they contain. Ointments contain the most oil so can be quite greasy, but they are the most effective at keeping moisture in the skin. Lotions contain the least oil so are not greasy but can be less effective. Creams are between the two.   

If you have been using a particular emollient for some time, it may start to irritate your skin. If this happens, speak to your GP as another product can be prescribed instead.  

How to use emollients

Use your emollient frequently and in large amounts. You may want to keep separate supplies of emollients at work or at school.

To apply the emollient:

  • use a large amount 
  • smooth the emollient into the skin in the same direction that the hair grows 
  • do not rub the emollient in
  • for very dry skin, apply the emollient every two to three hours 
  • after a bath or shower, gently dry the skin and then immediately apply the emollient while the skin is still moist 
  • do not share emollients with other people

Creams and lotions tend to be more suitable for red, weepy and wet areas of skin. Ointments are more effective for areas of dry skin. However, as they are greasier, you may dislike the way they affect your appearance.

If you are exposed to irritants at work that cause your contact dermatitis, make sure that you apply emollients regularly during and after work.

Side effects

The most common side effect of using emollients is irritation of the skin, such as a rash. If you have contact dermatitis, your skin will be sensitive and can sometimes react to certain ingredients within the emollient. If your skin reacts to the emollient, stop using it and speak to your GP, who will be able to prescribe an alternative product.

If you are using an emollient for the first time, you may want to apply a small amount before applying it to a widespread area. This will allow you to check whether your skin reacts to it or not.

Some emollients contain paraffin and can be a fire hazard. As some emollient products are highly flammable, they should not be used near a naked flame.

Emollients that are added to your bath can make your bath very slippery, so take care getting in and out. As long as you are aware of these hazards, you should be able to use emollients safely. 

Topical corticosteroids

If your skin is very red, sore and inflamed, your GP may prescribe a topical corticosteroid (one that is applied directly to your skin). Corticosteroids work by quickly reducing inflammation.

Corticosteroids are any type of medication that contains steroids, a type of hormone. Hormones are groups of powerful chemicals that have a wide range of effects on the body.

You may be concerned about using medication that contains steroids. However, corticosteroids are not the same as anabolic steroids, which are sometimes used (illegally) by bodybuilders and athletes. When used correctly, corticosteroids are a safe and effective treatment for contact dermatitis.

Choice of topical corticosteroid

Different strengths of topical corticosteroids can be prescribed depending on the severity of your contact dermatitis and where the affected skin is. You may be prescribed:

  • a stronger topical corticosteroid for short-term use in severe contact dermatitis
  • a weaker topical corticosteroid if the eczema is mild
  • a weaker topical corticosteroid for use on your face, genitals or in the creases of your joints (such as your elbows), as your skin is thinner in these areas
  • a stronger topical corticosteroid to use on your palms and the soles of your feet, as the skin is thicker here

How to use topical corticosteroids

When using corticosteroids, apply the treatment in a thin layer to all the affected areas. Always follow the directions on the patient information leaflet that comes with the corticosteroid. This will give details of how much you should apply.

During an episode of severe contact dermatitis, do not apply the corticosteroid more than twice a day. Most people will only have to apply it once a day. To apply the topical corticosteroid:

  • Apply your emollient first and wait several minutes before applying the topical corticosteroid, until the emollient has soaked into your skin.
  • Apply a small amount of the topical corticosteroid to the affected area (see the box, above right, for a guide on the amount your should use). 
  • Continue to apply the treatment for 48 hours after the contact dermatitis has cleared up.
  • Return to your GP if your contact dermatitis has not improved after two weeks.

Side effects

Topical corticosteroids may cause a mild burning or stinging feeling as you apply them. In some areas, if used for long periods, they may also cause:

  • thinning of the skin, particularly in the crease of the elbow or knee joint
  • telangiectasia (visible blood vessels), particularly on the cheeks 
  • acne (spots) 
  • increased hair growth, although this is rare

Generally, using a stronger topical corticosteroid or using a large amount of topical corticosteroid may increase your risk of developing side effects. For this reason, always use corticosteroids as prescribed by your doctor.

Corticosteroid tablets

If you have a severe episode of contact dermatitis and it covers over a fifth of your skin, your GP may prescribe corticosteroid tablets.

You may be prescribed prednisolone to take for five to seven days. Depending on how effective this is, your dose of prednisolone may gradually be reduced over two or three weeks. 

If corticosteroid tablets are taken often or for a long time, they can cause a number of side effects, such as:

  • affecting the growth rate of children
  • high blood pressure (hypertension) 
  • osteoporosis (brittle bones)
  • inflammation of the stomach lining

For this reason, your GP is unlikely to prescribe corticosteroid tablets more than once a year without referring you to a specialist (see referral, below).

Infected contact dermatitis

If your contact dermatitis is infected, your GP may use a swab to take a sample of the skin. A swab is a small piece of absorbent material, such as gauze or cotton, attached to the end of a stick or wire. The sample can then be tested to see what is causing the infection.

You will usually be prescribed an oral antibiotic. You may be prescribed:

  • flucloxacillin
  • clarithromycin (if you are allergic to penicillin)

Sometimes, an antibiotic or antiseptic cream is all that is needed.

Referral 

In some severe cases of contact dermatitis, your GP may refer you for assessment and treatment by a dermatologist. For example, your GP may refer you if:

  • It is not clear what is causing your contact dermatitis.
  • The prescribed treatments are not successfully controlling your contact dermatitis.  
  • You have long-term or recurring symptoms despite avoiding the causes and using the treatments prescribed. 

Further treatments

Treatments from a dermatologist could include:

  • phototherapy, where your contact dermatitis is exposed to ultraviolet (UV) light - this may be ultraviolet A or ultraviolet B, and may also involve a medicine containing psoralen, which makes your skin more sensitive to light
  • steroid-sparing immunosuppressant therapy - immunosuppressant medicines suppress your immune system (the body's natural defence system)
  • alitretinoin (see below)

Alitretinoin

Alitretinoin (sold under the brand name Toctino) is a medication for severe, long-term hand eczema that has failed to respond to other treatments, such as topical corticosteroids. Treatment with alitretinoin must be supervised by a dermatologist and can only be used by people who are 18 years of age or over.

Alitretinoin is a type of medication called retinoids. Retinoids reduce the levels of irritation and itchiness associated with eczema.

Alitretinoin comes as a capsule that most people are recommended to take once a day for 12-24 weeks.

Alitretinoin should never be taken during pregnancy because it can cause severe birth defects. Also avoid taking alitretinoin when breastfeeding because the medication can enter your breast milk and harm your baby.

Due to the risk of birth defects, the use of alitretinoin is not recommended for women of child-bearing age. If you are a woman of child-bearing age, you will only be prescribed alitretinoin if you agree to the following strict rules:

  • You fully understand why you should not get pregnant and what you need to do to prevent it.
  • You agree to use one or preferably two methods of contraception, including a barrier form of contraception such as condoms.
  • You start using these contraception methods from one month before starting treatment until one month after finishing treatment. 
  • You agree to have pregnancy tests before, during and after treatment.
  • You confirm that you are aware of the risks and the precautions you need to take, for example by signing a form stating this.

Some common side effects of alitretinoin include:

  • headaches
  • dry mouth 
  • anaemia (a reduced number of red blood cells)
  • flushed (warm and red) skin
  • increased levels of cholesterol and triglyceride (fatty substances) in the blood 
  • joint or muscle pain
  • dry eyes or eye irritation

Uncommon side effects of alitretinoin include nosebleeds and sight problems, such as blurred vision. If you have vision problems, stop treatment immediately and contact your dermatologist.

There have also been reports of people suddenly having thoughts of hurting or killing themselves while taking retinoids, which are related to alitretinoin. However, to date, this has never been reported with alitretinoin.

It may be helpful to tell a close friend or relative that you are taking alitretinoin and ask them to tell you if they notice changes in your behaviour or are worried about the way you are acting. If you have any concerns, let you dermatologist know.

Allergen
An allergen is a substance that reacts with the body's immune system and causes an allergic reaction.

Irritant
An irritant is a substance that damages the skin physically.

Inflammation
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.

How much topical corticosteroid to use

  • Topical corticosteroids are measured in a standard unit called the fingertip unit (FTU).
  • One FTU is the amount of topical steroid squeezed from the end of your index (first) finger to the first crease.
  • One FTU is enough to treat an area of skin twice the size of an adult's hand.

Contact dermatitis can cause some complications. These are explained below. 

Quality of life

Most people can manage their contact dermatitis symptoms effectively. However, for some, the symptoms may be severe and long lasting and may affect their quality of life.

For example, contact dermatitis may affect your ability to do your job. This may cause you to feel unhappy or depressed. If your symptoms have a significant impact on your quality of life, speak to your GP. They may be able to help you manage your symptoms more effectively.

Bacterial infection 

Contact dermatitis can become infected with bacteria, usually Staphylococcus and Streptococcus. This is more likely if you frequently scratch your dermatitis or if your skin is cracked as this provides an opening for bacteria to enter.

The infection can cause a condition called impetigo, which is a highly contagious bacterial skin infection. Alternatively, the infection can make your dermatitis symptoms get worse very quickly, for example:

  • Your skin will become redder, hotter and more painful. 
  • It may start to ooze fluid and crust over.
  • You may feel generally unwell or have a high temperature.

See your GP if your dermatitis symptoms are unusual or get suddenly worse. If you have an infection, it can usually be easily treated with antibiotics (medication to treat infections caused by bacteria).

The best way to prevent contact dermatitis is to avoid contact with the allergens or irritants that cause your symptoms. However, this is not always possible. If you cannot avoid contact, you can take steps to reduce the risk of the allergens or irritants causing symptoms.

Washing or cleaning your skin

If you come into contact with an allergen or irritant, rinse the affected skin with water or wash it using a very mild soap or preferably a soap substitute (an emollient, see below). Do this as soon as possible after coming into contact with the allergen or irritant.

Using protective clothing

You can wear protective clothing to reduce the contact you have with the allergens or irritants.

Irritant contact dermatitis usually affects the hands, so gloves are an easy and effective way of minimising your contact with an irritant. You could wear cotton gloves underneath gloves made of rubber, if the rubber also irritates you. Take your gloves off every now and again as sweating will make any symptoms you have worse.

If you work with chemicals, there may be health and safety guidance at work that tells you what sort of gloves you need to wear.

Changing products

If you know that a certain product causes your contact dermatitis, such as a type of make-up or soap, try changing to a different product. Check the ingredients to make sure it does not contain any allergens or irritants that affect you. In some cases, you may need to contact the manufacturer to get this information.

Emollients

Apply emollients frequently and in large amounts. These will keep your skin hydrated and help the skin repair itself. Once it is repaired, your skin can provide better protection against contact with allergens and irritants.

Also use emollient soap substitutes as soap can dry out your skin. This is particularly important if you need to wash your hands frequently at work.

Barrier creams

Barrier creams can be applied to create a barrier between you and the irritant. If used correctly, they may help prevent contact with the irritant. However, do not rely on them as your only form of protection.

After-work creams

After-work creams are designed to be used at the end of your working day. Applying after-work creams may reduce the number of times contact dermatitis occurs. 

Allergen
An allergen is a substance that reacts with the body's immune system and causes an allergic reaction.

Irritant
An irritant is a substance that damages the skin physically.

Content provided by NHS Choices www.nhs.uk and adapted for Ireland by the Health A-Z.

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