When to get help

Call emergency services — 999 in the UK, 112 or 999 in Ireland and the EU, 911 in the US and Canada, 000 in Australia, 111 in New Zealand — if your baby has any of these, which the NHS lists for roseola specifically:

blue, grey, pale or blotchy skin, lips or tongue — on brown or black skin this may be easier to see on the palms and soles;
a rash that does not fade when you roll a glass over it, the same as meningitis;
difficulty breathing: grunting noises, the stomach sucking in under the ribcage, breathlessness or breathing very fast;
a weak, high-pitched cry that is not their normal cry;
not responding as they normally do, or not interested in feeding or normal activities;
sleepier than normal or difficult to wake.

Ask for an urgent GP appointment or call an advice line if your baby is under 3 months with a temperature of 38°C (100.4°F) or higher, is 3 to 6 months with 39°C (102.2°F) or higher, has had a high temperature for 5 days or longer, is refusing fluids or feeds, is showing signs of dehydration such as nappies that are not very wet, sunken eyes and no tears when crying, or is simply not their usual self and you are worried.

The NHS also lists a high temperature that does not come down with paracetamol or ibuprofen as a reason to seek urgent advice for roseola. Note that this is not the same as saying a temperature that does come down is reassuring — NICE tells clinicians the opposite, that a response to antipyretics should not be used to separate serious from non-serious illness.

The shape of the illness

Roseola is a very common infection that mainly affects babies and toddlers. It runs in two clear phases, which is what makes it recognisable in hindsight and impossible to identify at the start.

Phase one: the fever

A sudden high temperature, often with cold-like symptoms — a sore throat, runny nose and cough — loss of appetite, and swollen eyelids and swollen glands in the neck. The NHS says these symptoms last 3 to 5 days before a rash appears.

Phase two: the rash

The rash is made up of pinkish-red spots, patches or bumps. It may be harder to see on brown or black skin. It starts on the chest, tummy and back, then spreads to the face, neck and arms. It is not usually itchy or uncomfortable, and normally fades and disappears within 2 days.

Why the rash is the good news

In most childhood illnesses a rash arriving means things are progressing. In roseola it usually means the fever phase is ending. Parents often describe a run of frightening high temperatures with no explanation, followed by a baby who suddenly seems well but is covered in spots. That sequence — fever first, rash as the fever breaks — is the classic pattern.

It also explains why roseola is rarely diagnosed while it is happening. During the fever phase there is nothing to see, and the correct response is to treat it as any unexplained fever in a baby: apply the NICE age thresholds and watch for red flags.

Do the glass test anyway

The NHS puts a non-blanching rash on its emergency list for roseola, which tells you something. A new rash in a baby who has had several days of high fever is exactly the scenario in which meningococcal disease also presents. Press a clear glass firmly against the spots. If they fade, that fits roseola. If they stay visible, call an ambulance. On brown or black skin, check the palms, soles, inside the eyelids and the roof of the mouth, where a non-blanching rash is easier to see.

Looking after them at home

Let them rest if they feel unwell.
Make sure they drink plenty of fluids — for a baby, normal milk feeds offered more often.
Children's paracetamol or ibuprofen if a high temperature is making them uncomfortable. Check the dose on the bottle or ask a pharmacist; the NHS notes paracetamol is not for babies under 2 months and ibuprofen is not for babies under 3 months or under 5 kg (11 lb), or for children with asthma.
Do not cover them in too many clothes or bedclothes.
Do not give aspirin to under-16s, and do not combine ibuprofen and paracetamol unless a GP tells you to.

Nursery and childcare

Keep your baby at home while they have a high temperature, which the NHS says is when roseola is thought to be most contagious. Once the temperature has passed you do not need to keep them away, and there is no need to wait for the rash to disappear. That is the opposite of the instinct most people have when a visible rash is present.

Febrile seizures and roseola

A high temperature that climbs quickly is the setting in which febrile seizures happen, and roseola produces exactly that pattern. The NHS lists a seizure among the things that can happen when a child has a high temperature, and a first fit always needs emergency assessment — call an ambulance rather than driving. Most febrile seizures last two to three minutes and do no harm, but none of that is a reason to manage a first one at home.

Worth repeating here because roseola tempts people into it: NICE states that antipyretic agents do not prevent febrile convulsions and should not be used for that purpose. Giving paracetamol every few hours through the fever phase in the hope of heading off a seizure is not supported by the guidance, and NICE's advice is to use these medicines only while a child appears distressed.

One group who should call

The NHS flags a specific exception: speak to a GP if you or your child has a weakened immune system and has had contact with someone with roseola, because it can be serious. That includes anyone having chemotherapy or taking medicines that suppress immunity. For everyone else, the infection should pass within a week.

Roseola