Contact dermatitis

Contact dermatitis is an inflammatory skin condition where your skin reacts to contact with a chemical or something you’re allergic to.

There are two types of contact dermatitis:

• Allergic contact dermatitis — when you become hypersensitive to something, so your skin reacts the next time it’s in contact with it
• Irritant contact dermatitis — when your skin comes into contact with a chemical that damages the surface of your skin

Irritant contact dermatitis is much more common than allergic contact dermatitis because it’s easy to come into contact with a chemical or irritant at work or at home.

Anyone can get contact dermatitis, but women are more likely to be affected and people who already have atopic dermatitis.

Hands are affected in four out of five cases. Hand dermatitis is common in occupations such as hairdressers, nurses and cleaners as they’re often washing their hands.

Avoiding contact with the allergen or irritant will usually help reduce the symptoms, although treatments such as moisturisers and steroid creams may be needed.

Contact dermatitis can affect your daily life and work. Treatment success depends on the cause of your contact dermatitis and how long you’ve had it.

Contact dermatitis can cause small blisters or cracks, as well as patches of dry, thickened skin. If you are light-skinned, your skin may become red. If you are dark-skinned, your skin may become darker brown, grey or purple.

The damage caused by contact dermatitis can lead to a skin infection. Signs of infection include: 

• Discharge (fluid) leaking from your skin
• Feeling unwell, hot or shivery
• Pain
• Worsening of your current symptoms over a very short period of time

Allergic contact dermatitis symptoms

Allergic contact dermatitis can happen quite slowly after you’ve been in contact with the allergen (eg make-up or metal jewellery). Your skin will become red and itchy usually over several days.

Symptoms include: 

• Blisters that ooze fluid
• Dry, flaky, leathery or scaly skin
• Hives
• Itching, redness and a burning sensation 
• Sensitivity to the sun 
• Swelling — particularly of the face, around the eyes and the groin area

Irritant contact dermatitis symptoms

Irritant contact dermatitis usually happens very soon after contact with the chemical. Your skin will become red and sore after a few hours or a day. However, milder irritants (eg certain soaps or detergents) may take longer to cause a skin reaction or need multiple exposures for them to cause a reaction. 

Symptoms include: 

• Blisters
• Cracked, dry skin
• Open sores with crusts
• Stiff or tight skin
• Ulcers

It’s important to get a proper diagnosis so you can get the right treatment and prevent your contact dermatitis from becoming a chronic (long-term) condition, which may be harder to treat.

It’s often possible to diagnose contact dermatitis from your history. Your doctor will look at your skin and ask you about your work or activities, particularly in the hours and days before you first noticed the symptoms.

Your doctor may also refer you to a dermatologist (a doctor specialising in treating skin problems). They may use a patch test — the application of very small amounts of different allergens and irritants on your skin — to find out what your skin is reacting to.

Contact dermatitis is caused by allergens or irritants that cause your skin to become inflamed — inflammation is your skin’s reaction to try to protect itself against the allergen or irritant.

Causes of irritant contact dermatitis 

Irritant contact dermatitis is caused by frequently allowing your bare skin to come into contact with a substance that damages it. These include:

• Antiseptics and antibacterials, cleaning products, detergents, disinfectants and soaps
• Certain plants eg Boraginaceae, mustards, ranunculus and spurge
• Chemicals used at work eg acids and alkalis, cement, machine oils, solvents
• Dust
• Perfumes, powders and preservatives in toiletries or cosmetics
• Water — particularly chalky, hard water or heavily chlorinated water (eg in a swimming pool)

The symptoms can be made worse by heat, cold or humidity.

You are more likely to develop irritant contact dermatitis if you work in certain occupations, such as agricultural workers, beauticians, caterers, chemical workers, cleaners, construction workers, cooks, electronics, hairdressers, healthcare workers, machine operators, mechanics, metalwork and vehicle assembly.

Causes of allergic contact dermatitis

Allergic contact dermatitis is caused by contact with something you’ve previously become allergic to, sometimes without realising it. These are called allergens and include:

• Hot water
• Ingredients in cosmetics eg fragrances, hair dye, nail varnish hardeners and preservatives
• Ingredients in certain skin creams and topical medicines
• Metals such as cobalt and nickel, which are often used in jewellery
• Rubber and latex
• Some plants, such as chrysanthemums, daffodils, primula, sunflowers and tulips 

You may also develop allergic contact dermatitis from dyes and resins used in certain textiles, as well as from strong glues (eg epoxy resin adhesives). 

Contact dermatitis can affect any part of your body that comes into contact with an allergen or irritant. It therefore commonly affects the most exposed parts of your body ie eyelids, hands, legs, lips and neck. 

However, contact dermatitis can also affect your genital area, the penis or vulva. Contact dermatitis of the vulva is usually caused by irritants including: 

• Chemicals on new clothes
• Douches or feminine sprays
• Fragrances in menstrual products
• Latex condoms or lubricants
• Laundry detergents

Contact dermatitis of the penis is usually caused by irritants including: 

• Cologne 
• Laundry detergent
• Soap
• Spermicide

Contact dermatitis of the penis usually develops a few minutes or hours after exposure to the irritant and can last for up to a month — it is not contagious and can't be sexually transmitted. 

The most effective way to prevent contact dermatitis is to avoid the irritant or allergen that triggers it. However, if you don’t know what is causing your contact dermatitis, make sure you: 

• Only use dye-free and fragrance-free creams, detergents, lotions and soaps
• Test new products on a small patch of your skin before using it on the rest of your body
• Use a barrier cream eg petroleum jelly to protect your skin and prevent it from drying out
• Wear protective clothing if you are around potential allergens or irritants eg wear gloves and goggles when using cleaning products and wear long sleeves and trousers when exposed to the sun or near plants

Home remedies

The first step is to avoid whatever is causing your skin to react. This may involve changes at work or changing the soaps and detergents you use at home. If you are exposed to an irritant or allergen, wash it off your skin as soon as possible.

Try not to scratch your irritated skin as this can worsen your symptoms and cause infection. If you develop an infection, see your GP; they can prescribe antibiotics to treat your infection.

To help prevent you from scratching your affected skin, try using an anti-itch treatment eg calamine lotion or hydrocortisone cream. If your itching persists, you can try an over-the-counter antihistamine, such as diphenhydramine — speak to your pharmacist before taking it.

Make sure you apply an unscented moisturiser to the affected areas of your skin to reduce dryness and cracking, or apply a barrier cream such as petroleum jelly to help prevent your skin from drying out. Clean your skin with a mild, unscented soap and lukewarm water to remove any irritants or allergens.

Medical treatments

If your contact dermatitis doesn't improve with home remedies, covers a large area of your skin or is around your eyes or mouth, see your GP. They may prescribe a stronger corticosteroid cream and/or refer you to a dermatologist for further treatments, such as: 

• Alitretinoin capsules — these are prescribed to treat severe eczema of the hands
• Immunosuppressant therapy — medication to suppress your immune system and therefore reduce inflammation of your skin
• Phototherapy — your affected skin is exposed to ultraviolet (UV) light to reduce inflammation and itching and therefore improve the appearance of your skin

Alternative treatments

There is currently no conclusive evidence to support the effectiveness of food supplements or herbal remedies in treating contact dermatitis.