Printed on: December 11th, 2025

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Feverish illness in children under 5

Feverish illness in children under 5

It can feel like young children are sick almost all the time, and no wonder – the median number of infective episodes between birth and 3 years of age in healthy children is 16 (JAMA 2025;8:e2453284).

Fever in children is a common reason to present to primary care, and most will have a self-limiting viral illness: a 2010 study estimated that 99% of febrile children aged 0–5y have a ‘non-serious’ cause (BMJ 2010;340:c1594).   

Our difficult, but important, task is to spot those kids who might be in the 1%.

The NICE feverish illness in children guidance has met with some criticism following a large UK study which questioned the diagnostic accuracy of the NICE traffic-light system in identifying children with serious illness in primary care.

In this article, we summarise what NICE says, detail the concerns that have been raised, and provide a useful framework for how you might assess a feverish child in your practice, whether you are assessing remotely or face to face.

This article was last updated in March 2025.

Please follow the link for a PDF version of the GEMS for download/printing: Feverish illness in children under 5: GEMS

NICE concluded that neither paracetamol nor ibuprofen were better than the other, and that combined therapy should not be routinely used because there is:

• Increased risk of adverse reactions, particularly if the child is dehydrated.
• Increased risk of confusion and overdosing.
• No evidence of clinically significant benefit in terms of child distress.

It also acknowledges the increased NHS costs of dual prescribing of paracetamol and ibuprofen for febrile illness, and recommends that if a prescription is to be issued, it should be for one agent or the other.

However, in the 2013 guidance, it does acknowledge the findings of the PITCH study, a small UK-based RCT of children with fever randomised to paracetamol, ibuprofen or both (BMJ 2008;337:a1302). This study showed:

• Initial fever reduction after the first dose: ibuprofen or combined therapy were equally good at reducing fever and keeping it down in the first 4h, and were better than paracetamol alone.
• Fever control in first 24h: combined therapy was better than ibuprofen or paracetamol alone at keeping fever away in the first 24h.
• Distress in the first 48h: no drug/combination of drugs was any better at reducing distress scores in the first 48h.
• There was no difference in adverse reactions between the three groups.

Remember that in chickenpox, NSAIDS should be used with caution due to possible increased risk of invasive skin infections (BJCP 2007;65(2):203).

We can share this with parents and allow them to choose their preferred agent, reserving combined therapy for those children where either agent alone does not relieve distress.

Fever >5 days is classed by NICE as an ‘amber’ sign on the traffic-light risk-stratification table. In primary care, our management will most likely be decided by how confident we are of the underlying cause.

NICE advises that where no diagnosis has been reached, we should refer to paediatricians for further assessment, OR provide a safety-net with warning signs of deterioration and plans for repeat review in place. We think this often means a conversation with our local paediatrician colleagues.

An article aimed at paediatricians summarised the causes to consider (Paed 2020;30:7,261). Although this will be a secondary care assessment, we felt it might be useful to include the headline conditions here to help you direct your history-taking in primary care (and also help you persuade your hard-pressed hospital teams to take your referral!).

* HLH is a very rare immune disorder where the body reacts inappropriately to a ‘trigger’, usually an infection, and this results in severe inflammation that causes damage, especially to the liver, spleen and bone marrow. Hard to diagnose as often mimics severe infection. Can be familial or acquired. Managed in specialist centres. (GOSH – information for parents and visitors: haemophagocytic lymphohistiocytosis)

Of course, if we think about symptoms other than fever, many childhood illnesses last longer than parents expect…

An older systematic review aimed to establish the duration of common childhood illnesses, and looked at how this compared with national guidelines and patient information sites (BMJ 2013;347:f7027).

This table usefully summarises the results. ‘NK’ is shown where no data was available.

Not yet.

As we noted in the GEMS (above), NICE’s traffic light system is far from perfect. A BJGP study found multiple issues with its accuracy, including (BJGP 2022;72:e398):

• Overestimation of risk in the red group.
• Underestimation of risk in the amber group.
• Almost all children (94%) being categorised as amber or red.
• Low sensitivity (58.8%) and specificity (68.5%).

Another BJGP study (BJGP 2025;75:e98) looked at two alternative scoring systems – the National Paediatric Early Warning Score and the Liverpool quick Sequential Organ Failure Assessment score – but neither performed well in assessing children in primary care for risk of subsequent hospital admission. The authors say that further research is needed to create and validate an accurate scoring system for our clinical context.

Until a better score is developed, we suggest using NICE’s traffic lights alongside a hefty dose of clinical judgement, paying particular attention to illness trajectory (as discussed earlier). And remember, while objective assessment of feverish children is very important, parental concern and clinician instinct are also strong red flags (Lancet 2010;375:834).

A helpful 2025 BJGP editorial (BJGP 2025;75:52) looked at this in detail, and we summarise it here.

These four essentials come from a Delphi consensus on safety-netting acutely-ill children from back in 2009 (BJGP 2009;59:872). The BJGP editorial feels that they’re still relevant today, as do we!

1. What exactly to look out for.
2. How exactly to seek further help.
3. What to expect (including specifics about the time course of the illness if known).
4. The existence of diagnostic uncertainty, if present.

Taken directly from the BJGP editorial, common pitfalls are:

• Providing only vague advice, for example, “any problems, come back” or “come back if it’s not better” without specifying a timeframe.
• Overemphasising certain symptoms, or using symptoms associated with the disease as red flags, e.g. telling a parent of a child with a vomiting illness to return if the vomiting persists (the red flag is signs of dehydration, not vomiting).
• Assessing multiple problems in one consultation, but failing to safety-net issues raised after the first problem.
• Patients being unable to recall verbal safety-netting advice.
• Assuming patients can access or understand online resources without confirming this.

Here are some ways to avoid these pitfalls:

• Include specific safety-netting as part of the management plan, rather than using it to close the consultation.
• Use pre-set text messages or leaflets for common conditions, and include specific safety-netting advice in these.
• Share with patients that research has identified safety concerns associated with addressing multiple problems in a single consultation, to help manage their expectations.
• Check whether patients can access text/online advice or need an alternative format.

The short answer is that combined verbal and written advice seems most effective.

A 2025 network meta-analysis looked at this question specifically in relation to acutely-ill children. It found that (BJGP 2025;75:e90):

• Written safety-netting reduces antibiotic prescribing and reconsultation rates compared with usual care.
• Other formats (e.g. video and online resources) improve other measures such as parental knowledge and satisfaction.

An earlier systematic review similarly found that parents retained more knowledge about managing acute childhood illness when verbal and written information were provided together compared with written advice alone (BMJ Open 2015;5:e008280).

Interestingly, the BJGP editorial raises the question of whether there will be a future role for generative artificial intelligence (AI) tools capable of summarising clinical encounters and creating and documenting real-time safety-netting. Watch this space!

We’ve listed some examples in the useful resources box at the end of this article.

The BJGP editorial mentioned above looked specifically at safety-netting acutely-ill/feverish children, but, given that this skill is so crucial in this context, we’ve also included a refresher summary on a good general safety-netting skills below. You may also find our article on Safety-netting in primary care useful.

Roger Neighbour identified three key questions the clinician can ask themselves. If we answer these questions in our safety-netting, we’ve probably done a good enough job (The Inner Consultation, Oxford: Radcliffe Publishing, 2004):

• If I’m right, what do I expect to happen?
• How will I know if I’m wrong?
• What would I do then?

A 2022 BMJ paper looked at prompts to consider when providing safety-net advice using the mnemonic SAFER (BMJ 2022;378:e069094).

How could you apply this framework to safety-netting with the family of a feverish child?

	Feverish illness in children under 5 In children <4w old, use an axillary digital thermometer to take temperature; in older children, axillary digital or chemical dot thermometers, or infrared tympanic monitors, are acceptable. Take parental reports of fever seriously. Measure and record temperature, heart rate, respiratory rate and capillary refill time. Recognise that children with tachycardia are of at least intermediate risk: <12m: >160bpm. 12–24m: >150bpm. 2–5y: >140bpm. Look for a source of the fever, and treat or refer as appropriate. Remember to have a low threshold for checking urine. Risk-stratify children as per the traffic-light table, and consider whether the traffic lights are changing: swings and slides approach. If seeing face to face, refer children with red features for urgent paediatric assessment. If assessing remotely, ensure children with red but not life-threatening features are seen for face-to-face assessment within 2h. Do not prescribe antibiotics for children with fever without a source. Parental concern and clinician instinct are important red flags. Make safety-netting part of the management plan; include specifics; and back-up verbal safety-netting advice with written resources.
	Audit 20 febrile illness consultations. How many included documented pulse, respiratory rate, CRT and temperature? Discuss these guidelines at your PHCT meeting and re-audit 1m later.
	Useful resources: Websites (all resources are hyperlinked for ease of use in Red Whale Knowledge) Resources for parents to back-up verbal safety-netting: HANDi App When Should I Worry? (available in 15 languages) YouTube - NHS Minor Illnesses Playlist NHS - Little Orange Book