Babies get a lot of rashes. Milia, baby acne, heat rash, drool rash and diaper rash are all common, and nearly all of them are harmless. But a small number of rashes are signs of serious illness that can get worse within hours. This guide is about telling those apart, so you know when to relax and when to act fast.
If you’re reading this because your baby seems very unwell right now, stop reading and call 911.
Call 911 or go to emergency now
Get emergency help right away if your baby has a rash along with any of these. This list is based on NHS advice for rashes in babies and children, and on Canadian public health guidance on meningococcal disease, a serious bacterial infection of the blood and the lining of the brain.
- A rash that does not fade when you press a glass against it, especially one that looks like small bruises, pinpricks or bleeding under the skin, or reddish-purple spots.
- Trouble breathing or very fast breathing.
- Sudden swelling of the lips, mouth, tongue or throat.
- Skin, lips or tongue that look pale, blue, grey or blotchy.
- Your baby is floppy, stiff, unusually hard to wake, or doesn’t respond to you normally.
- A high-pitched or unusual cry.
- A bulging soft spot (fontanelle) on the top of the head.
- A stiff neck or seeming bothered by light.
The Public Health Agency of Canada notes that babies with meningococcal disease may be slow or inactive, vomit, feed poorly, be irritable, seem less alert, or have swelling on the soft spot. It also warns that complications can develop very rapidly. Don’t wait to see if it gets better.
How to do the glass test
The glass test helps you check whether a rash “blanches”, meaning it fades when pressed. Most everyday rashes blanch. A rash that doesn’t can mean bleeding into the skin, which is one of the signs of meningococcal infection.
- Take a clear drinking glass.
- Press the side of the glass firmly against the rash.
- Look through the glass. If you can still clearly see the spots, the rash is not fading.
A rash that doesn’t fade under the glass is an emergency. Call 911 or go straight to the nearest emergency department.
Two important cautions from the NHS:
- Not every baby with meningitis gets a rash, and it can appear late. A baby with the other warning signs above needs emergency care even if the skin looks clear.
- On brown or black skin, a rash can be harder to see. Check lighter areas: the palms, the soles of the feet, the lips, the tongue and the inside of the eyelids.
Fever plus rash: why your baby’s age matters
A fever changes how quickly a rash needs attention, and in young babies the rules are stricter.
The Canadian Paediatric Society says babies younger than three months with a fever should be seen urgently, and babies younger than six months with a fever should see a doctor. It defines fever as a rectal or ear temperature above 37.9 °C, or an oral or armpit temperature above 37.5 °C.
It also advises contacting a health care provider for a child with a fever plus a rash, or a child who is excessively sleepy, lethargic or unresponsive, or excessively cranky and irritable. The NHS adds that you should get urgent advice if a baby under three months has a temperature of 38 °C or more.
So a rash with a fever in a young baby isn’t something to watch overnight. Call your doctor or health line the same day, and go to emergency if any of the signs in the first list appear.
Blisters, peeling and raw skin
Blisters in a newborn deserve special attention.
- Herpes simplex. In a newborn, the virus that causes cold sores can cause a serious infection. The Canadian Paediatric Society says symptoms usually appear within the first four weeks of life, and may include clusters of blisters on the skin, eyes or mouth. Most mothers of affected babies have no known history of herpes, and some babies never develop skin blisters at all. Any blisters in a baby under about six weeks need a doctor the same day, and a newborn with blisters who also has a fever or seems unwell needs emergency care.
- Scalded skin. Staphylococcal scalded skin syndrome is caused by a toxin from staph bacteria. DermNet describes fever and irritability followed by tender red skin, starting on the face and in skin folds, then large, fragile blisters that burst and leave raw, burn-like skin. It mostly affects children under five and needs hospital treatment. With treatment, children usually heal well.
Skin that is peeling in sheets, looks burned, or is very painful to touch should be seen urgently.
See a doctor soon: not an emergency, but don’t wait weeks
Some rashes need a doctor within a day or two, but not an ambulance. Book a same-day or next-day visit, or call your provincial health line, if:
- the rash looks infected: spreading redness, warmth, swelling, pus, or honey-coloured crusts
- a diaper rash is severe, has blisters or open sores, or isn’t improving after a few days of care
- your baby seems very itchy or uncomfortable and isn’t sleeping
- hives (raised, itchy welts) appear after a new food or medicine, without any swelling of the face or trouble breathing
- the rash comes with a fever in a baby older than six months who otherwise seems well
Always trust your instincts. The NHS puts it well: you know your child best. If you’re worried, it’s right to get advice.
Rashes that can usually wait for a routine visit
Many baby rashes are harmless and settle with simple care, as long as your baby is feeding well, alert and has no fever. The NHS guide to rashes in babies includes several of these:
- Milia: tiny white bumps on the nose and cheeks.
- Baby acne and erythema toxicum (a blotchy newborn rash).
- Heat rash: tiny red bumps where your baby was too warm.
- Mild eczema, cradle cap and mild diaper rash.
Mention them at your next check-up if they bother you, or sooner if they don’t improve.
Most rashes in babies are nothing to worry about. The ones that can’t wait have a pattern: a rash that doesn’t fade under a glass, trouble breathing or swelling, a floppy or unusually sleepy baby, blisters in a newborn, or any fever in a baby under three months. If you see any of these, call 911 or go to emergency. If you’re unsure, call your doctor or health line. Nobody will think you overreacted.
Related questions
My baby has a fever but no rash. Can I wait for a rash to appear?
No. The NHS says not everyone with meningitis gets spots or a rash, and the rash can come late. A baby who is floppy, hard to wake, has a high-pitched cry, won’t feed or has a bulging soft spot needs emergency care, rash or no rash. And any fever in a baby under three months should be seen urgently.
How do I check a rash on dark skin?
Redness can be hard to see on brown or black skin. The NHS suggests checking the palms, the soles of the feet, the lips, the tongue and the inside of the eyelids, where colour changes such as paleness, blue or grey tones, or small spots are easier to spot. The glass test works on any skin tone.
What counts as a fever in a baby?
The Canadian Paediatric Society considers a rectal or ear temperature above 37.9 °C, or an armpit temperature above 37.5 °C, to be a fever. A baby under three months with a fever should be seen urgently, and under six months should see a doctor.
Are most baby rashes serious?
No. Most rashes in babies, such as milia, baby acne, heat rash, drool rash and mild diaper rash, are harmless and settle with simple care. The point of knowing the warning signs isn’t to worry about every spot. It’s to recognize the rare rash that can’t wait.
Sources
- Rashes in babies and children
- Meningitis: symptoms
- Invasive meningococcal disease: symptoms and treatment
- Fever and temperature taking
- Prevention and management of neonatal herpes simplex virus infections
- Staphylococcal scalded skin syndrome
This article is general information, not medical advice. If you have a concern about your skin, talk to your doctor or pharmacist.