Contact dermatitis

Contact dermatitis is inflammation caused by a substance that touches and irritates the skin or triggers an allergic reaction. It is not contagious.

There are two main types.

Irritant contact dermatitis occurs when a substance damages the skin's protective outer layer. Common causes include water, soap, detergent, solvents, cleaning products, and bodily fluids. Repeated mild exposure is more common than a single severe exposure.

Allergic contact dermatitis occurs when your immune system becomes sensitive to a substance called an allergen. Once sensitised, even a small exposure may cause a reaction. The rash often appears hours or days later, making the trigger difficult to recognise.

Contact dermatitis often affects the hands, face, eyelids, feet, or areas under jewellery and clothing. It can interfere with sleep, work, and everyday tasks. Finding and avoiding the trigger gives the skin the best chance to recover.

Symptoms usually occur where the substance touched your skin, although allergic contact dermatitis can spread beyond that area.

Possible symptoms include:

• Itching, burning, soreness, or stinging
• Red, pink, purple, grey, or darker patches
• Dry, rough, cracked, or scaly skin
• Swelling, small bumps, or fluid-filled blisters
• Oozing and crusting during a strong reaction
• Thickened skin after repeated rubbing or long-term inflammation

Redness may be less visible on brown or black skin. The area may instead look purple, grey, or darker than the surrounding skin. Darker or lighter marks may remain after the rash settles.

Irritant contact dermatitis may cause immediate burning and soreness after a strong exposure or develop gradually as dryness and painful cracks. Allergic contact dermatitis is often very itchy and commonly begins one to several days after exposure. The location or shape can offer clues, such as a rash beneath a watch or in the pattern of a cosmetic product.

Common irritants include soaps, detergents, disinfectants, solvents, cement, oils, dust, repeated water exposure, and prolonged contact with bodily fluids.

Healthcare workers, cleaners, hairdressers, food handlers, mechanics, construction workers, and others who regularly do “wet work” are more likely to develop hand dermatitis. Wet work includes repeated handwashing or keeping the hands wet for long periods.

Common allergens include:

• Nickel and other metals in jewellery, fasteners, or tools
• Fragrances and preservatives in cosmetics and personal care products
• Ingredients in hair dyes, nail products, and skin adhesives
• Rubber chemicals in some gloves, shoes, and elastic
• Plants such as poison ivy, poison oak, and poison sumac
• Some antibiotic like amoxicillin or doxycycline creams and other medicines applied to the skin

An allergy can develop after months or years of trouble-free contact. Once the immune system is sensitised, the allergy often remains long term.

Atopic eczema weakens the skin barrier and increases the risk of irritant contact dermatitis. Some substances cause a reaction only when exposed skin also receives sunlight; this is called photocontact dermatitis.

A healthcare professional will examine your skin and ask when and where the rash began and what touches that area. Your work, hobbies, gloves, jewellery, cosmetics, skin treatments, and household products may provide clues.

There is no single laboratory test for irritant contact dermatitis. Diagnosis is usually based on the rash, exposure history, and improvement after avoiding the suspected irritant.

If allergic contact dermatitis is suspected, you may be offered patch testing. Small amounts of common allergens are placed on your back under adhesive patches. The patches remain for a set period, and the skin is checked for delayed reactions over several days.

Patch testing differs from a skin-prick test, which looks for immediate allergies such as hay fever or some food allergies. A positive patch test must also be matched with your actual exposures.

Atopic eczema, psoriasis, fungal infections, and scabies can look similar. A skin scraping, fungal test, or small skin sample may be needed if the diagnosis is uncertain.

The most important treatment is identifying and avoiding the cause. Related chemicals may have different names, so labels can be difficult to interpret. After patch testing, you may receive a list of names and products to avoid.

If a substance has just touched your skin, rinse it off promptly with lukewarm water. Do not scrub hard, as this may cause further damage.

Moisturisers, or emollients, help repair the skin barrier. Thick, fragrance-free creams or ointments are often less irritating than scented lotions. Reapply them after handwashing and whenever the skin feels dry.

Topical corticosteroids can reduce itching, swelling, and redness during a flare. The correct strength and treatment length depend on your age, the affected area, and the severity. Delicate areas such as the eyelids and skin folds need particular care.

Steroid-sparing prescription creams may be used on sensitive skin or when repeated treatment is needed. Severe or widespread dermatitis may require a short course of treatment that works throughout the body and must be medically supervised.

Cool compresses or wet dressings may soothe weeping or blistered skin. Antihistamines like cetirizine or loratadine do not treat the delayed inflammation, although some may help with sleep when itching is severe.

Protective gloves can reduce exposure, but their material must suit the substance. Sweat inside gloves may worsen irritation, and rubber chemicals can cause allergy. Cotton liners and regular glove changes may help during prolonged use.

Scratching and cracked skin can allow bacteria to enter. Signs of infection include increasing pain, warmth, swelling, pus, spreading redness or darkening, and feeling unwell. Yellow crusts can also occur, although crusting is not always caused by infection.

Repeated inflammation may make skin thick, rough, and deeply cracked, reducing movement and making everyday tasks painful. Skin colour changes can remain for months, particularly in darker skin.

Ongoing workplace exposure may cause chronic hand dermatitis, time away from work, or difficulty performing tasks. Occupational health support may identify safer products, protective equipment, or working methods.

Allergic sensitisation cannot usually be reversed, but avoiding the allergen can prevent many future flares. Irritant dermatitis may be reduced by limiting exposure and supporting the skin barrier.

Helpful measures include:

• Use lukewarm rather than very hot water
• Choose gentle, fragrance-free cleansers
• Apply an unperfumed moisturiser after washing
• Wear suitable protective clothing or gloves for wet or chemical work
• Remove contaminated clothing and rinse exposed skin promptly
• Follow workplace safety instructions for chemicals and protective equipment

“Natural” and “hypoallergenic” do not mean allergy-free. Plant extracts, essential oils, fragrances, and preservatives can still cause reactions. Avoiding all skincare products is rarely necessary; focus on confirmed or strongly suspected triggers.

Skin may take several weeks to settle after the trigger is removed. Hands often recover slowly because they continue to encounter water, friction, and everyday products.

Irritant contact dermatitis may clear when exposure stops but can return if wet work or chemical exposure resumes. Allergic contact dermatitis usually improves when the allergen is avoided, although the sensitivity often remains. Accidental exposure may cause another flare months or years later.

Some people have both irritant and allergic contact dermatitis or also have atopic eczema. This can explain why avoidance helps without fully clearing the skin.

Routine follow-up is useful when the rash keeps returning, the trigger is unclear, treatment is not controlling symptoms, or work makes avoidance difficult. Patch testing or occupational skin advice may help.

Arrange a routine medical appointment if the rash is persistent, recurrent, painful, widespread, or interfering with sleep or daily activities. Seek advice if it affects your eyes, face, genitals, or hands, or if you cannot identify the trigger.

Get prompt medical help if the skin rapidly becomes more painful, hot, or swollen, produces pus, or develops spreading redness or darkening, especially if you have a fever or feel unwell. These may be signs of infection.

Seek urgent assessment after a significant chemical exposure, particularly if there is severe pain, skin damage, or eye contact. Follow the product's emergency instructions and do not try to neutralise one chemical with another.

Call emergency services if an exposure is followed by trouble breathing, wheezing, faintness, or swelling of the lips, tongue, mouth, or throat. These symptoms suggest a serious immediate allergic reaction rather than ordinary contact dermatitis.

Is contact dermatitis contagious?

No. It is an inflammatory reaction, not an infection. Shared products or workplace exposures may cause similar rashes in several people, but the rash has not spread between them.

How long does contact dermatitis last?

It may improve within days after the trigger is removed, but full healing can take several weeks. Continued exposure, scratching, infection, or another skin condition can prolong it.

Can contact dermatitis spread around my body?

Allergic contact dermatitis may extend beyond the contact area, especially during a strong reaction. Products transferred by your hands can also affect several areas. A new or rapidly spreading rash should be assessed because other conditions can look similar.

What is the difference between contact dermatitis and eczema?

Contact dermatitis is a type of eczema caused by something touching the skin. Atopic eczema is linked to a weaker skin barrier and an overactive inflammatory response. A person can have both.

Can I suddenly become allergic to a product I have used for years?

Yes. Allergic sensitisation can develop after repeated exposure, so past tolerance does not rule out a new allergy. Patch testing can help identify delayed allergies.

Will patch testing find every possible trigger?

No. It tests selected allergens and may not include every substance you encounter. Results must be compared with your products, work, and hobbies. Patch testing does not confirm irritant reactions.