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How do you know when a baby is unwell? What the NHS says about fever, feeding, and sickness, and why we tracked every feed

The NHS website lists situations where it says to call 111 or get urgent help, including a baby under 3 months with a temperature of 38C or higher, a baby who does not want to eat or is not their usual self, and a baby who is refusing to feed.[1][2] This page summarises those NHS pages and adds our own experience. It is not medical advice.

By Tom, a dad of two in Kent. Published 3 October 2026. NHS pages last checked 3 October 2026.

How this page works. Every health fact here comes from the NHS website and links to the page it came from, with that page's review date. The "In our house" box is our own experience. Nothing here is advice. For advice, go to the NHS page, your health visitor, or your GP.

What counts as a high temperature

The NHS says a high temperature is 38C or more. It says a high temperature is very common in young children and usually returns to normal within 1 to 4 days.[1]

The NHS says to use a digital thermometer placed inside the top of the armpit, and that a child's temperature may be higher for a short time after a bath or after being wrapped in a blanket.[1]

When the NHS says to call 111 about a high temperature

The NHS page says to call 111 if your child:[1]

  • is under 3 months old and has a temperature of 38C or higher, or you think they have a high temperature[1]
  • is 3 to 6 months old and has a temperature of 39C or higher, or you think they have a high temperature[1]
  • has other signs of illness, such as a rash, as well as a high temperature[1]
  • has a high temperature that has lasted for 5 days or more[1]
  • does not want to eat, or is not their usual self and you are worried[1]
  • is dehydrated, for example with nappies that are not very wet, sunken eyes, and no tears when they are crying[1]

When the NHS says to call 999

The NHS page says to call 999 if your child:[1]

  • has a stiff neck, or is bothered by light[1]
  • has a rash that does not fade when you press a glass against it[1]
  • has a fit (febrile seizure) for the first time, where they cannot stop shaking[1]
  • has unusually cold hands and feet[1]
  • has changes to their skin colour, such as blue, grey, paler than usual, or blotchy skin, or blue, grey, or paler than usual lips or tongue[1]
  • is drowsy and hard to wake[1]
  • is extremely agitated, which means they do not stop crying, or is confused[1]
  • has difficulty breathing, such as grunting noises, their stomach sucking under their ribcage, breathlessness, or breathing very fast[1]
  • is not responding like they normally do, or is not interested in feeding or normal activities[1]

The NHS page also covers looking after a child with a high temperature at home, including fluids, checking on them regularly through the night, and which medicines can be given at which ages. Read that section on the NHS page itself.[1]

Reflux and being sick

The NHS says reflux is when a baby brings up milk, or is sick, either while feeding or shortly after. It says reflux is very common and usually gets better on its own. It usually starts before a baby is 8 weeks old and gets better by the time they are 1.[2]

It says it is common for a baby under 1 to bring up a little milk during or shortly after a feed without being distressed, and that a baby does not usually need to see a doctor if they are happy, healthy, and gaining weight.[2]

When the NHS says to see a GP about reflux

The NHS page says to see a GP if your baby:[2]

  • is not improving after trying things to ease reflux[2]
  • gets reflux for the first time after they are 6 months old[2]
  • is older than 1 and still has reflux[2]
  • is not gaining weight or is losing weight[2]

When the NHS says to get urgent help about reflux or sickness

The NHS reflux page says to ask for an urgent GP appointment or call NHS 111 if your baby:[2]

  • has vomit that is green or yellow, or has blood in it[2]
  • is projectile vomiting, which means being sick with more force than usual[2]
  • has blood in their poo, or has a swollen or tender tummy[2]
  • has a very high temperature, or they feel hot, cold, or shivery[2]
  • keeps being sick and cannot keep fluid down[2]
  • has diarrhoea that lasts for over a week, or has signs of dehydration[2]
  • will not stop crying and is very distressed[2]
  • is refusing to feed[2]

The page adds that you can also call your GP or 111 if you have any other concerns about your baby.[2]

In our house

Our eldest was sick a lot when he was little, often around milk time. Our youngest had a few infections very early on, so after that, any dip in one of her feeds made us worry she was ill. Reflux and sickness worried us with both children. We tracked every milk feed, and we were almost too accurate about it, while our nappy counts were more of a guess.

In our youngest's first week, and again at around three months, her feeds dropped over the course of a day, with no temperature. We took her to hospital, where we were told she was probably fine and did not look ill. Her infection markers turned out to be very high, and in her first week they were the highest the doctor had seen. After that, we wanted a record of every milk feed in case it happened again. This is what happened to us, not advice. The NHS pages linked here are where to read what the NHS says to do.

If you are worried

This page is a summary of NHS information plus our own experience. It is not medical advice. If you are worried about your baby, you can use NHS 111, or speak to your health visitor or GP. The NHS pages on high temperature (fever) in children and reflux in babies list when it says to call 111 or 999.

Sources

  1. NHS website: High temperature (fever) in children. Page last reviewed 3 January 2024; next review due 3 January 2027; page last updated by the NHS on 9 September 2026. I checked it on 3 October 2026.
  2. NHS website: Reflux in babies. Page last reviewed 10 June 2025; next review due 10 June 2028; page last updated by the NHS on 9 December 2025. I checked it on 3 October 2026.

Contains public sector information licensed under the Open Government Licence v3.0. This page summarises NHS website content in our own words, and an adaptation may not carry the NHS's formal clinical approval. Tiny Tummies is not affiliated with or endorsed by the NHS.

About the author

I am Tom, a dad of two in Kent. When I wrote this, our children were 3 years 9 months and 16 months old. I am not a clinician, and nothing here is medical advice. I also built Tiny Tummies, a baby feeding tracker. I use AI tools to help draft these pages. Every health fact is checked against the NHS page it links to, and the "In our house" boxes are what my wife and I actually did.