Dermatitis: types, treatment, causes and whether it is contagious

Dermatitis means inflammation of the skin. In everyday use it overlaps heavily with eczema: the NHS calls atopic eczema "atopic dermatitis" and describes contact dermatitis as a type of eczema, which it defines as a group of conditions that cause skin to become dry and irritated.

What dermatitis looks like depends on the type and on your skin tone. The NHS describes affected skin as itchy, dry, cracked, crusty, scaly or thickened, sometimes blistered or bleeding. On lighter skin it can look red; on darker skin it can look dark brown, purple or grey, or lighter or darker than the skin around it.

Flare-ups and quieter periods are typical. The NHS notes that atopic eczema usually starts in babies and young children and tends to improve with age, although it can begin at any age.

Different types have different triggers and different patterns on the body, which is why a correct label matters for treatment. The table summarises the types described by the NHS and NICE CKS.

No. The NHS states plainly that atopic eczema is not contagious, so you cannot catch it from someone else or pass it on. The other types listed above are also reactions or conditions of your own skin, driven by irritants, allergens, dry skin, yeast on the skin (in the case of seborrhoeic dermatitis) or leg vein pressure, rather than a germ that spreads between people.

The exception to be aware of is infection on top of dermatitis. Broken skin can become infected, and the NHS lists blistering, crusting, leaking fluid or pus-filled spots as possible signs. Infected eczema needs medical assessment, and one serious complication, eczema herpeticum, is a viral infection that needs prompt treatment.

Do not share emollients: the NHS advises against sharing them with anyone else and against putting fingers into the pot, to avoid contaminating them.

Treatment depends on the type, but the foundations are similar. For atopic eczema the NHS names emollients and topical corticosteroids as the main treatments, with special dressings or other medicines depending on severity. A GP can prescribe some treatments or refer you to a dermatologist.

For contact dermatitis, the NHS says that if you can successfully avoid the irritants or allergens that trigger your symptoms, your skin will eventually clear up. Emollients and topical corticosteroids are used when avoidance is not entirely possible. Oral corticosteroids are rarely prescribed for a severe episode covering a large area.

• Emollients: apply as often as possible (at least twice a day according to the NHS) and keep going even when skin improves. Use an emollient to wash instead of soap.

• Topical corticosteroids: creams, lotions or gels for flare-ups, prescribed by a GP, with strength matched to the site and severity.

• Antihistamines: the NHS lists these for discoid eczema to reduce itching, and sedating antihistamines for pompholyx if itching disrupts sleep.

• Seborrhoeic dermatitis: NICE CKS describes ketoconazole 2% shampoo or anti-dandruff shampoo for the scalp, and topical imidazole creams with short courses of mild steroid for the face and body.

• Varicose eczema: the NHS lists self-help to improve circulation, emollients, topical corticosteroids and compression stockings.

• Infection: antibiotic cream or tablets may be needed if the skin is infected.

The NHS lists practical steps for atopic eczema that apply well to most types of dermatitis. Avoiding triggers is as important as medicines.

• Avoid things that make it worse, such as soap, washing detergent, some fabrics or pets.

• Keep cool, because being hot can make eczema itchier.

• Keep nails short, and use anti-scratch mittens for babies.

• Try gently rubbing the area rather than scratching.

• Do not use aqueous cream, which can irritate the skin and make eczema worse.

• Do not change your diet unless a doctor tells you to.

• Do not smoke or go near naked flames if you use emollients: they can make fabrics such as dressings, clothing and bedding catch fire more easily.

• For contact dermatitis, wear gloves (cotton liners under rubber gloves can help), rinse off any irritant quickly with warm water and an emollient, and check product ingredients.

The cause depends on the type. The NHS says it is not always known what causes atopic eczema, and that you are more likely to have it if a parent has it, or you or a close relative has asthma or hay fever. It can be made worse by irritants and allergens, heat or temperature changes, skin infections such as staph, stress and hormonal changes such as those during pregnancy.

Contact dermatitis is caused by an irritant that directly damages the outer layer of skin, or an allergen that causes the immune system to respond in a way that affects the skin. The NHS says irritant contact dermatitis is the more common kind, triggered by soaps and detergents, solvents or regular contact with water. Allergic contact dermatitis is less common and can be triggered by cosmetics or metals such as nickel.

The cause of discoid eczema is unknown, although the NHS says it may follow very dry skin, and it can be triggered by minor injuries such as insect bites or burns. Varicose eczema is usually caused by increased pressure in the leg veins when vein valves stop working properly. For seborrhoeic dermatitis, NICE CKS says the exact cause is not fully understood and Malassezia yeasts and immune response have been associated with it.

It varies a great deal by type, and many types come and go. The NHS says there is no cure for atopic eczema but symptoms tend to improve as you get older, with flare-ups and better periods in between.

Contact dermatitis typically settles when the trigger is found and avoided. Discoid eczema, according to the NHS, can last for weeks, months or even years without treatment and may return, often in the same area. A pompholyx flare usually lasts 2 to 3 weeks, although the condition itself is usually long term.

NICE CKS describes infantile seborrhoeic dermatitis (cradle cap) as usually self-limiting, resolving at around 8 to 12 months, whereas in adults it is chronic and may relapse and remit over many years while responding well to treatment.

Ask for an urgent GP appointment or call NHS 111 if you or your child have eczema and any of the following, the NHS advises. These can be signs of infection or a more serious condition called eczema herpeticum.

• The skin is blistered, crusty, leaking fluid or has spots filled with pus.

• It is painful, swollen or feels warm.

• It suddenly gets worse or gets bigger.

• You have a high temperature or feel generally unwell.

• The NHS says to check symptoms on 111 online for anyone aged 5 and over, or call 111 for children under 5.

A GP can usually diagnose dermatitis by examining the skin and asking questions. The NHS says this is the case for discoid eczema and varicose eczema, and a GP may check leg pulses and do an ankle brachial pressure index (ABPI) test to see whether compression stockings are suitable.

A referral to a dermatologist may follow if the diagnosis is uncertain, treatment is not working, or a patch test is needed to identify an allergen. The NHS says this applies for contact dermatitis where the substance cannot be identified.

Most people start with a pharmacist or GP. A pharmacist can recommend emollients and other treatments for mild, small-area dermatitis, according to the NHS. A GP can diagnose, prescribe and refer to dermatology if needed.

NHS dermatology is delivered by referral, so waiting times depend on local services. Some people choose to see a private dermatologist for faster access to assessment or patch testing. A private consultation is separate from NHS care, and your GP can share information on request. Either way, treatment is typically built on the same first-line steps described above.

Living with long-term dermatitis can be difficult. The NHS notes that if it affects your mental health, you may be referred to a mental health specialist. Itch-related sleep loss and visible skin can take a toll, and it is reasonable to raise this with a GP.

Charities such as the National Eczema Society provide practical information and support, and the NHS signposts Eczema Care Online for self-management advice.