What is the glass test for rashes?

Press a clear glass firmly against the rash. If it fades, it is blanching. If the colour stays, it may be non-blanching — a possible sign of meningitis or sepsis. Call 999 if this happens with fever and your child being very unwell.

What does a chickenpox rash look like?

Spots that start red, become fluid-filled blisters, then scab over — often starting on the chest or face. Very itchy. New spots can appear in batches over several days.

When is a rash just nappy rash?

Nappy rash causes red, sore skin in the nappy area. Change nappies frequently, use barrier cream, and give nappy-free time. See a GP if the rash is severe, blistered, or not improving — it may be thrush or a bacterial infection needing treatment.

Can teething cause a rash?

Teething can cause drooling that irritates the chin (drool rash). A teething rash is localised around the mouth. Teething does not cause a widespread body rash — that usually indicates an infection.

Should I send my child to school with a rash?

It depends on the cause. Keep them home if they have a fever, feel unwell, or have an infectious rash such as chickenpox (until spots crust over) or scarlet fever (until 24 hours after starting antibiotics). Check with the school or nursery if unsure.

Rashes in babies and children

Quick answer

What could rashes in babies and children mean?

Rashes are very common in children and are often caused by viral infections, eczema or harmless skin reactions. Many clear up without treatment. Call 999 if a rash does not fade when pressed with a glass, if your child is struggling to breathe, or if they are confused, floppy or difficult to wake with a rash and fever.

Rashes are common in children

Most rashes in babies and children are harmless and caused by viral infections, eczema, or minor skin irritation. Parents understandably worry — especially with so many names in the news — but the majority of rashes settle without special treatment.

Knowing a few patterns helps, but how unwell your child seems matters more than the rash alone.

Rashes that need emergency help

Call 999 if your child has:

a rash that does not fade when you press a clear glass against it (the glass test)
difficulty breathing or blue lips
is confused, floppy, or difficult to wake
a rash with a stiff neck and severe headache

These can be signs of meningitis, sepsis, or a severe allergic reaction.

Common childhood rashes

Chickenpox — itchy spots that blister and scab. Very common and usually mild. Infectious until all spots crust over.

Slapped cheek syndrome — bright red cheeks, sometimes a lace-like body rash. Usually mild; pregnant women exposed should seek advice.

Hand, foot and mouth disease — mouth ulcers plus spots on hands and feet. Common in nurseries.

Scarlet fever — fine sandpaper-like rash with sore throat and fever. Needs antibiotics from a GP.

Eczema — dry, itchy patches, often in skin creases. Not infectious. Managed with moisturisers and sometimes steroid creams from a GP.

Hives — raised, itchy welts that come and go. Often allergic; antihistamines help.

Heat rash — small red spots in hot weather. Keep cool and dress lightly.

Nappy rash — sore red skin in the nappy area. Frequent changes, barrier cream, and nappy-free time help.

The glass test

This simple check helps identify dangerous rashes:

Press a clear drinking glass firmly against the rash.
If the rash fades under the glass — it is blanching (less likely to be meningococcal).
If the rash does not fade — seek emergency help, especially with fever and drowsiness.

The test is not perfect, but a non-blanching rash with a very unwell child is an emergency.

Caring for a rash at home

For mild, non-urgent rashes:

keep nails short to reduce scratching damage
use fragrance-free moisturiser on dry skin
dress in loose cotton clothing
offer fluids and comfort
paracetamol or ibuprofen for fever (age-appropriate dosing)

Avoid new bath products or detergents until the rash clears — they may irritate sensitive skin.

When to see a GP

See a GP if:

the rash is not improving after a week
your child has a rash with a persistent high temperature
you suspect scarlet fever (sandpaper rash + sore throat)
nappy rash is severe or not responding to simple measures
you are unsure of the cause and worried

Trust your instincts. You know your child — if they seem seriously unwell, seek help even if the rash looks mild.

Infectious rashes and school

Keep your child home if they have a fever, feel unwell, or have an infectious rash. Specific guidance varies — chickenpox until spots crust, scarlet fever until 24 hours after antibiotics. Check with your nursery or school.

Common questions

What is the glass test for rashes?: Press a clear glass firmly against the rash. If it fades, it is blanching. If the colour stays, it may be non-blanching — a possible sign of meningitis or sepsis. Call 999 if this happens with fever and your child being very unwell.
What does a chickenpox rash look like?: Spots that start red, become fluid-filled blisters, then scab over — often starting on the chest or face. Very itchy. New spots can appear in batches over several days.
When is a rash just nappy rash?: Nappy rash causes red, sore skin in the nappy area. Change nappies frequently, use barrier cream, and give nappy-free time. See a GP if the rash is severe, blistered, or not improving — it may be thrush or a bacterial infection needing treatment.
Can teething cause a rash?: Teething can cause drooling that irritates the chin (drool rash). A teething rash is localised around the mouth. Teething does not cause a widespread body rash — that usually indicates an infection.
Should I send my child to school with a rash?: It depends on the cause. Keep them home if they have a fever, feel unwell, or have an infectious rash such as chickenpox (until spots crust over) or scarlet fever (until 24 hours after starting antibiotics). Check with the school or nursery if unsure.

Sources

NHS — Rashes in babies and children