Contact Dermatitis

The irritants

• Water itself. Frequent hand washing and prolonged wet work are the leading cause, and this surprises people — water strips the skin's lipid barrier
• Soaps, detergents and washing-up liquid
• Alcohol hand gels, which sting damaged skin but are actually less damaging than repeated washing
• Solvents, oils, cutting fluids, cement and plaster
• Friction, and prolonged glove occlusion — sweat trapped inside gloves is itself an irritant
• Cold, dry air and low humidity, which is why it worsens every winter

The common allergens

• Nickel — the commonest contact allergen. Jewellery, watch backs, belt buckles, jean studs, phone cases, glasses frames
• Fragrance — including in products labelled "unscented", which may contain masking fragrance
• Preservatives, particularly methylisothiazolinone — which caused a genuine epidemic of facial and hand dermatitis after it was introduced widely into wet wipes, shampoos and household cleaners
• Hair dye (paraphenylenediamine) — a major cause in hairdressers and in clients, and the ingredient behind black henna tattoo reactions
• Rubber accelerators in gloves — which is why the gloves worn to protect the skin sometimes turn out to be the problem
• Topical medicines — including neomycin, and the preservatives in some creams. Yes, this includes steroid creams themselves
• Plants — particularly the daisy family, in gardeners
• Methacrylates in gel and acrylic nails — an increasingly common cause in nail technicians and clients

Jobs where this is an occupational disease

Hairdressing, nursing and healthcare, catering and food preparation, cleaning, construction, engineering, agriculture, florists, beauty therapy. If your skin improves on holiday and deteriorates within days of returning to work, that is not a coincidence and it has legal implications.

What makes it more likely

A history of atopic eczema, asthma or hay fever — a damaged barrier is easier to irritate and easier to sensitise through. Filaggrin gene variants have the same effect.

Contact dermatitis is diagnosed from the pattern and the history — and the history is where nearly all the information is. Clear photographs plus a careful conversation cover it well remotely.

The questions that identify the cause

• Where exactly did it start, and what shape is it? Geometric edges mean contact
• Does it improve at weekends or on holiday, and return within days of going back to work? The single most valuable question, and the one that establishes occupational causation
• What is your job, and what do your hands touch during it?
• How many times a day do you wash your hands, and do you wear gloves — what kind, and for how long at a stretch?
• Hobbies — gardening, cycling, swimming, DIY, playing an instrument
• Every product that touches your skin, including partner's products, and anything new in the last three months. Remember the 24 to 72 hour delay when you think back
• New jewellery, a new phone case, new glasses, a new watch strap
• What you have already applied to it — because a treatment can become the allergen
• Any personal or family history of eczema, asthma or hay fever

Tests

• Patch testing is the definitive test for allergic contact dermatitis, and it is quite different from the allergy tests people are familiar with. Patches are applied to the back and read at 48 and 96 hours. It must be done in a dermatology clinic, not remotely, and we refer for it
• Blood IgE and skin prick tests do not diagnose contact dermatitis. They test a different kind of immune reaction entirely. A normal allergy blood test does not exclude contact allergy, and this is a very common source of false reassurance
• A skin swab where infection is suspected — weeping, golden crusting, sudden worsening
• Where the picture is not typical, we consider thyroid function, ferritin and full blood count

What we cannot do remotely

Patch testing, and examination of an unclear rash. A widespread rash, a rash not responding to correct treatment, or one where we cannot confidently exclude psoriasis, fungal infection or something rarer needs to be seen. Fungal infection in particular is regularly treated as dermatitis, which makes it spread — so a one-sided, ring-shaped or slowly expanding patch always deserves a second look.

Hands — the changes that matter most

• Wash less, and cooler. Lukewarm water, a small amount of emollient wash, and dry thoroughly — especially between the fingers, where dermatitis starts
• Use alcohol gel instead of washing where hands are not visibly soiled. Counter-intuitive, but gel is less damaging to the barrier than repeated soap and water. It stings cracked skin, which is why people avoid it
• Rings off before wet work. Detergent trapped underneath a ring is a classic cause of a patch that will not clear
• Emollient after every wash. Keep a tube by every sink, in your bag and by the bed — convenience is what determines whether it actually happens

Gloves — the detail almost everyone gets wrong

• Wear a thin cotton glove inside the rubber one. Sweat trapped against the skin is itself an irritant, and this single change makes gloves genuinely protective rather than partly harmful
• Never wear rubber gloves for more than about 20 minutes at a stretch without a break
• Use non-latex, accelerator-free gloves if you react to gloves themselves
• Wear gloves for cold weather too — cold and wind damage the barrier

Finding the culprit

• Think back 24 to 72 hours, not to this morning. The delay is the reason most people identify the wrong product
• Keep a simple diary of products, activities and flares over a fortnight
• Change one thing at a time. Changing everything at once tells you nothing
• Beware "hypoallergenic", "natural" and "dermatologically tested" — none of these are regulated claims, and plant extracts and essential oils are common allergens
• "Unscented" can still contain masking fragrance. "Fragrance-free" is the phrase to look for

At work

Your employer has a legal duty under COSHH to assess and control skin exposure, and occupational dermatitis is reportable under RIDDOR. You are entitled to appropriate gloves, barrier arrangements, and skin surveillance in higher-risk jobs. Raise it formally rather than managing alone — and if it improves on leave and relapses at work, say so explicitly, as that is the evidence that matters. We can write an occupational health letter setting out the clinical position.

Around the house

• Nickel-free jewellery; surgical steel, titanium or gold
• Clear nail varnish over jean studs and buckles as a temporary barrier
• Non-biological detergent, an extra rinse cycle, and no fabric conditioner
• Rinse new clothes before wearing — particularly dark dyed items

Is this eczema or dermatitis?

The words overlap and are often used interchangeably. In practice, eczema usually means the inherited atopic kind that starts in childhood and comes with hay fever and asthma; contact dermatitis means skin inflamed by something it has touched. The distinction matters because contact dermatitis has a cause you can remove — see our eczema page for the atopic form.

How do I work out what is causing it?

Look 24 to 72 hours back, not at this morning. Allergic contact dermatitis is a delayed reaction, which is why people so reliably blame the wrong product. Note the shape too — a sharp geometric edge, a strap line, a patch under a watch — that geometry usually names the culprit. Where it stays unclear, patch testing finds it.

My allergy blood test was normal, so it can't be an allergy?

That is a common and misleading conclusion. Blood IgE and skin prick tests measure a completely different type of immune reaction and do not detect contact allergy at all. The only test that does is patch testing, applied to the back and read over several days in a dermatology clinic.

Are steroid creams going to thin my skin?

This worry causes far more harm than the creams do. Skin thinning comes from prolonged use of potent steroids on thin skin — face, eyelids, folds. Under-treating is the commoner problem: a short course of an adequately strong steroid clears things faster and with less total steroid than months of something too weak. Hands in particular need a potent preparation, because palm skin is thick.

Why isn't my cream working?

Usually one of four reasons: the exposure is still happening, so nothing can clear it; the steroid is too weak for the site; you are applying far too little — check the fingertip unit; or, less often but genuinely, you have become allergic to the cream itself, to the steroid or a preservative in it. Worth raising if nothing is helping.

Should I wear gloves at work?

Yes, with two conditions. Wear a thin cotton glove inside the rubber one, and take them off every 20 minutes or so. Sweat trapped inside a glove is an irritant in its own right, and gloves worn continuously without a cotton liner can make hand dermatitis worse rather than better — which is why some people conclude gloves do not help.

Could my job be causing this, and does that matter?

Very likely, if it improves on holiday and relapses within days of returning. It matters considerably: occupational dermatitis is reportable under RIDDOR, and your employer has legal duties to assess and control skin exposure. Raise it formally, keep a record of the pattern, and ask us for a letter. In some cases compensation applies. Almost nobody is told any of this.

Will I have it forever?

Irritant dermatitis usually settles once exposure is reduced and the barrier recovers, though badly damaged hands can take months. Allergic contact dermatitis is different — the sensitisation is permanent, so the allergy does not go away, but the dermatitis stays away as long as you avoid the substance. That is why identifying it precisely is worth the effort.

Is it contagious?

No. Dermatitis cannot be passed to anyone. If a rash is spreading between people in a household, it is something else — scabies, fungal infection or impetigo — and needs a different diagnosis.