Hand, Foot & Mouth Disease, Explained (Including the Eczema Version)

What it is

Hand, foot and mouth disease is a common viral infection, mostly of young children, that causes a fever, sore mouth, and a rash on — as advertised — the hands, feet, and inside the mouth.

It is caused by enteroviruses, most classically coxsackievirus A16, but also enterovirus A71 and, increasingly, coxsackievirus A6. That last one matters, because CVA6 has emerged over the past decade as a major cause of outbreaks worldwide and it tends to behave differently: more widespread rash, bigger blisters, and presentations that don't look like the textbook picture at all.

Over 90% of cases occur in children under five. It is not related to foot-and-mouth disease in livestock, despite the similar name.

What it looks like

The typical course runs like this:

• Incubation: 3 to 6 days after exposure
• First, usually a fever and a sore throat or mouth pain
• Then ulcers inside the mouth — on the inner cheeks, the tongue, sometimes the soft palate
• Then the rash: small macules, papules, or blisters, roughly 2–6 mm, often with a red ring around them

The rash classically appears on the hands and feet, but it also regularly turns up on the buttocks, legs, and the backs of the arms. Unlike most childhood rashes, it is typically not itchy and often not painful on the skin — though the mouth ulcers usually are, which is where most of the misery comes from.

Duration: it's self-limiting. The acute illness generally runs 10 to 14 days, with the rash resolving over roughly ten.

The version that gets missed: eczema coxsackium

Here's the part that catches families and clinicians out.

In a child who already has eczema, the same virus can produce a very different-looking illness called eczema coxsackium. Instead of politely staying on the hands and feet, the eruption preferentially lands wherever the eczema already is — and spreads much more widely across the body.

What it looks like:

• Painful, fairly uniform blisters that can progress to larger bullae, erosions, and scabs
• Concentrated on eczema-affected skin, active or previously affected
• Fever and sore throat commonly alongside
• In infants under one year, larger bullae are more likely; older children tend toward smaller vesicles
• Often no classic hand/foot/mouth pattern at all

A 2025 case report in the Sultan Qaboos University Medical Journal illustrates how confusing this can be: a 12-month-old with atopic dermatitis presented with widespread eczematous plaques and honey-coloured crusting on the back, limbs, and nappy area — with no blisters, no mouth lesions, and no hand or foot involvement. PCR confirmed coxsackievirus A6, plus a secondary staph infection on top.

Honey-coloured crust is the classic description of impetigo, which is exactly the point: these presentations get misdiagnosed. A 2023 review in Vaccines catalogued four atypical patterns — Gianotti-Crosti-like eruptions, eczema coxsackium, petechial or purpuric eruptions, and large vesiculobullous lesions — nearly all driven by CVA6, and noted that early on they closely resemble other conditions.

This is a good example of why a rash on a child with eczema deserves a real examination rather than a guess. It's also why our guidance across eczema treatment and baby eczema keeps returning to the same point: a sudden change in a child's eczema is a reason to be seen.

How it spreads

Through virus shed in secretions — saliva, blister fluid, and stool — usually picked up hand-to-mouth. Nurseries and preschools are the natural habitat.

Practical timeline:

Phase	What's happening
First week of illness	Most infectious
Up to ~4 weeks	Virus still shed from the throat
Up to ~6 weeks	Virus still shed in stool

Which means handwashing — especially around nappy changes and bathroom trips — stays relevant long after the child looks and feels fine. There is no way to be fully "clear" quickly, so exclusion policies generally hinge on the child being well and fever-free rather than on shedding.

What actually helps

There is no licensed antiviral treatment for it. Care is supportive, and the priorities are comfort and hydration:

• Pain and fever control with paracetamol/acetaminophen or ibuprofen, dosed for the child's weight
• Keep fluids going. This is the single most important thing. Painful mouth ulcers make children refuse to drink, and dehydration — not the virus — is the usual reason a child ends up needing medical care. Cold fluids, ice lollies, and soft, bland food are easier than anything acidic, salty, or hot
• Skip the mouthwashes and numbing gels unless a clinician has recommended a specific one for your child's age
• For eczema coxsackium specifically, DermNet's approach is emollients and keeping the skin hydrated, with topical steroids reintroduced once the fever has settled — worth discussing with your child's doctor rather than deciding alone, because the reason to pause and restart matters. Our guide to repairing a compromised skin barrier covers the general principles

When to see a doctor — and when it's urgent

See a doctor if:

• Your child isn't drinking or shows signs of dehydration — dry mouth, no tears, far fewer wet nappies, unusual sleepiness
• Your child has eczema and suddenly erupts in widespread blisters, weeping, or crusted sores
• The rash develops honey-coloured crusting, spreading redness, or increasing pain — a secondary bacterial infection may need antibiotics
• The illness is dragging past two weeks or getting worse rather than better
• Your child is a newborn, is immunocompromised, or you are pregnant and have been exposed

Seek urgent care immediately for:

• Lethargy that isn't just tiredness — a child who is difficult to rouse
• Seizures, or a stiff neck, or unusual confusion
• Difficulty breathing
• Any rash with non-blanching purple or red spots that don't fade under pressure — see when a rash is an emergency for the glass test

These reflect the rare but serious complications — aseptic meningitis, encephalitis, cerebellar ataxia, and, uncommonly, myocarditis or pulmonary complications — which are more associated with enterovirus A71 than with the milder strains.

A widespread blistering rash on a child with eczema also needs same-day assessment to rule out eczema herpeticum, a herpes simplex infection of eczematous skin that is a genuine emergency. It is not something to distinguish from eczema coxsackium at home, or from a photograph. If you're comparing against cold-sore-type infections, our cold sores article explains the herpes side of the picture.

The aftermath nobody warns you about

Two things commonly show up weeks after everyone has forgotten about the illness:

• Peeling palms and soles — sheets of skin coming off the hands and feet
• Nail changes at one to two months — horizontal ridges across the nail (Beau lines) or the nail lifting and shedding entirely (onychomadesis)

Both are well documented, both look far worse than they are, and the nails regrow normally. If you want the broader picture of what nail changes can signal, we cover it in what your nail changes can mean — but in this context, recent hand, foot and mouth disease is a sufficient explanation.

A note on where an assessment fits

This one is straightforward: an automated photo assessment is not the right tool here.

Hand, foot and mouth disease is an acute infection in a young child, it can mimic conditions that need urgent treatment, and the decisions that matter — hydration, secondary infection, ruling out eczema herpeticum — depend on examining the child, not the rash. Call your paediatrician or GP.

The dermatrix.life skin assessment is built for adults thinking about ongoing skin concerns, and it's informational rather than diagnostic. Once your child is well, if their underlying eczema is the recurring problem, that's a more reasonable thing to work on — starting with our eczema management guide and a conversation with their doctor.

The short version

A common, self-limiting childhood virus that usually just needs fluids, pain relief, and patience. The two things worth knowing beyond that: in a child with eczema it can look nothing like the textbook and spread widely across eczema-prone skin — and a sudden widespread blistering rash in that situation always deserves to be seen the same day.