Irritant contact dermatitis: causes, symptoms and treatment

Contact dermatitis is a type of eczema triggered by contact with a particular substance, according to the NHS. It has two main causes: an irritant, which is a substance that directly damages the outer layer of the skin, and an allergen, which causes the immune system to respond in a way that affects the skin. The irritant form is the commoner of the two.

The British Association of Dermatologists (BAD) explains that irritant contact dermatitis develops when the skin is repeatedly in contact with irritating substances for a long time, and gives examples including cleaning products, laundry detergents and everyday chemicals. The most important factors are how often the skin is exposed to detergents, powders, plants and solvents, and how concentrated they are.

NICE Clinical Knowledge Summaries list common irritants as repeated exposure to water, known as wet work, detergents, cleaning agents, acids and alkalis, and certain plants such as ranunculus. Anyone can develop it, but BAD notes it is more common in people who have previously had dermatitis such as eczema.

The two types can look alike, which is why a history of exposure matters. NICE CKS state that atopic dermatitis, allergic contact dermatitis and irritant contact dermatitis are not easily distinguished clinically and the cause may be mixed.

The NHS says contact dermatitis causes the skin to become itchy, blistered, dry and cracked. On lighter skin it can look red, and on darker skin it can look dark brown, purple or grey. The reaction usually occurs within a few hours or days of exposure and most commonly affects the hands and face. BAD says irritant contact dermatitis tends to cause burning, stinging, soreness and discomfort, and that the skin can swell and blister.

With repeated exposure, BAD says the skin can look thickened and leathery with splits or tears that are painful, and that painful splitting and cracking of the hands may reduce hand function. NICE CKS describe chronic disease as typically presenting with dryness, thickening and fissuring, and note that dermatitis in the webs of the fingers is suggestive of irritant contact dermatitis.

The NHS suggests speaking to a pharmacist if it is troubling you and seeing a GP if symptoms are persistent, recurrent or severe. BAD adds that a bacterial infection of contact dermatitis may lead to impetigo, which is very contagious and needs treatment, so any sign of infection should be reviewed promptly.

BAD says people whose work brings them into contact with solvents such as petrol, oils and other chemicals are at higher risk, and lists beauticians, cooks, florists, hairdressers, metalworking machine operatives, gardeners and healthcare practitioners as occupations where it is more common. Frequent handwashing can also cause irritant hand dermatitis in anyone.

The Health and Safety Executive covers this under its skin at work guidance, and NICE CKS point out that employers have legal duties to assess health risks at work and to prevent, or adequately control, exposure to hazards.

BAD says a doctor may suspect irritant contact dermatitis from a person's exposure to irritating substances, considering their job, lifestyle and hobbies, and that a rash in a specific area with typical dermatitis features helps confirm it. Patch testing, carried out in specialist dermatology departments, is used to identify the cause of allergic contact dermatitis, and NICE CKS note it may be required when the cause is unclear.

The NHS says a GP may refer you to a dermatologist if the substance cannot be identified or symptoms are not responding to treatment. NICE CKS list referral for work-related cases, for severe, chronic or recurrent dermatitis especially of the hands and face, and for dermatitis that is atypical or not responding to primary care measures.

The NHS says that if you can avoid the irritants or allergens, your skin will eventually clear up. As that is not always possible, you may be advised to use emollients to stop the skin drying out and topical corticosteroids to relieve severe symptoms; oral corticosteroids are rarely used for severe, widespread episodes. BAD adds that topical calcineurin inhibitors such as tacrolimus ointment or pimecrolimus cream can be used as a steroid-free option, and that it may take several months for contact dermatitis to settle.

BAD says there is no cure, but the condition can be managed by avoiding triggers, and in some cases that may mean changing jobs. If dermatitis is very severe, keeps coming back or covers a large area, a dermatologist may consider steroid tablets, and rarely medicines such as ciclosporin or methotrexate. BAD also warns that emollients can catch fire more easily when they get into contact with dressings, clothing, bed linen or hair, so extra care is needed near naked flames and cigarettes.

The NHS advises rinsing the skin with warm water and an emollient as soon as possible after contact with an irritant, using gloves to protect the hands but taking them off every now and again because sweating can make symptoms worse, changing products that irritate, and applying emollients frequently and in large amounts, including emollient soap substitutes. It suggests cotton gloves under rubber gloves if rubber irritates.

BAD recommends using an emollient several times a day, with thick emollients in the evenings and lighter products during the day, wearing gloves when needed and avoiding direct contact with soaps and detergents as much as possible. Cool compresses may help soothe sudden flare-ups.