Dermatitis

What is dermatitis?

Dermatitis is a general term for a group of conditions that cause inflammation of the skin, leading to dryness, redness and itchiness. It isn't one single illness, but covers several different types, including contact dermatitis, atopic dermatitis (eczema) and seborrhoeic dermatitis, each with its own triggers and pattern.

Symptoms of dermatitis

Symptoms vary depending on the type of dermatitis you have, but commonly include:

• itching, which is often the first sign
• dry, cracked or flaky skin
• redness, though on darker skin this can look more purple, deep brown or grey instead
• swelling
• fluid-filled blisters, which can weep, ooze or crust over
• thickened, leathery-looking skin, if the area is affected repeatedly over time
• burning, stinging, or a sensation like sunburn.

Dermatitis can appear anywhere on the body, but the hands and face are commonly affected. Occasionally, the affected skin becomes infected, particularly if it's been scratched or has open cracks.

Causes and who is at risk

Dermatitis usually develops from a combination of factors, and the exact cause varies by type:

• Your immune system: In some types, your immune system overreacts to substances that wouldn't normally cause a problem, leading to inflammation
• Genetics: Dermatitis can run in families, and researchers have identified gene changes that affect proteins your skin needs to stay healthy
• Your environment: Things like tobacco smoke, air pollution, fragranced products, and even the weather (heat, cold, low humidity) can affect your skin's protective barrier and trigger or worsen symptoms
• Direct contact with an irritant or allergen: Some substances damage the skin directly (irritants), while others trigger an allergic reaction in people whose immune system has become sensitised to them (allergens).

Common irritants include soap, detergents, solvents and frequent contact with water. Common allergens include certain metals (such as nickel and cobalt), fragrances, preservatives, hair dye, and some cosmetics.

You're at higher risk of irritant contact dermatitis if your job involves frequent hand-washing or contact with chemicals, for example in cleaning, catering, hairdressing, gardening or healthcare work, and if you already have eczema.

A family history of eczema, asthma or hay fever also increases your risk of irritant contact dermatitis, though allergic contact dermatitis isn't typically passed down in the same way.

Are there different types of dermatitis?

Yes, dermatitis covers several distinct conditions. Contact dermatitis is triggered by something touching your skin, and comes in two forms:

• Irritant contact dermatitis: A substance directly damages your skin, for example soap, detergent or solvents. This is the more common form.
• Allergic contact dermatitis: Your immune system reacts to a substance it has become sensitised to, such as certain metals, fragrances or hair dye. This usually develops over hours to days after contact, rather than immediately.

Other common types include:

• Atopic dermatitis (eczema): The most common type overall, often starting in childhood and running in families, alongside conditions like asthma and hay fever
• Seborrhoeic dermatitis: Causes flaky, itchy patches on oily areas such as the scalp and face; it's called cradle cap in babies, and dandruff when it affects the scalp alone
• Dyshidrotic dermatitis: Causes small, itchy blisters, mainly on the edges of the fingers, palms, toes and soles
• Nummular dermatitis: Causes coin-shaped, itchy patches, sometimes after an injury to the skin
• Stasis dermatitis: caused by poor blood flow in the veins, usually affecting the lower legs, with swelling, scaling and skin discolouration
• Neurodermatitis: An itchy patch of skin that develops from repeated scratching or rubbing, often triggered by stress
• Perioral (periorificial) dermatitis: A rash around the mouth, and sometimes the eyes or nose, that can look like acne.

How is dermatitis diagnosed?

Your doctor can usually diagnose dermatitis by examining your skin and asking about your symptoms, including where it started, how long you've had it, and anything that seems to trigger or worsen it, such as chemicals, soaps, stress or hot showers.

If the cause of contact dermatitis isn't obvious, or your symptoms aren't responding to treatment, you may be referred to a dermatologist for patch testing:

1. Small amounts of common allergens are taped to your back, or sometimes your upper arms, for two days
2. Your skin is then checked straight away, and again a couple of days later, since most allergic reactions take this long to develop
3. A small rash where a particular substance was applied, called a 'positive' patch test, tells your dermatologist which allergens to help you avoid.

Occasionally, other tests are used to rule out different causes or confirm the diagnosis, including a skin biopsy, blood tests or skin swabs.

How is dermatitis treated?

There's no single cure for dermatitis, since it covers so many different conditions, but most types can be managed well. Treatment usually follows similar general steps, whatever type you have.

1. Identify and avoid your triggers

This is the single most important step, particularly for contact dermatitis. If you can successfully avoid the substance responsible, your skin will often clear up on its own, though this can take several months. If you can't avoid a trigger completely, wearing gloves, changing to unscented products, and rinsing your skin promptly after contact can all help.

2. Look after your skin day to day

Follow this self-care guidance:

• Apply a fragrance-free emollient (moisturiser) frequently and generously; this is often more effective the more often it's used
• Use a soap substitute instead of regular soap, which can dry out your skin further
• Bathe or shower in lukewarm, rather than hot, water
• Avoid scratching, since this can break the skin and lead to infection
• Try to manage stress, since this can trigger or worsen flare-ups for some people.

3. If self-care isn't enough, speak to your doctor

Your doctor may prescribe:

• topical corticosteroids, applied as a thin layer to relieve inflammation, usually after your emollient (leave around 30 minutes between the two)
• other topical medicines, such as calcineurin inhibitors, for longer-term use in sensitive areas
• antihistamines, which can help with itching, particularly in contact dermatitis
• antibiotics, only if the affected skin becomes infected.

Oral corticosteroids are occasionally used for a severe flare covering a large area of skin, but this is uncommon.

When should I see a doctor?

Speak to a pharmacist first if your dermatitis is mild and troubling you; they can recommend suitable emollients and over-the-counter treatments.

See a GP if your symptoms are persistent, keep coming back, are severe, or aren't improving with treatment you've tried. See a doctor promptly, rather than waiting, if:

• you think the affected skin might be infected, for example if it's very painful, hot, swollen, or oozing pus
• the rash is spreading or getting worse despite treatment
• the itching or discomfort is affecting your sleep or daily life.