Fever is one of the most common reasons parents call NHS 111 or attend emergency departments with young children, and it is also an area where considerable parental anxiety exists that is not always well-matched to the actual risk the fever represents. Understanding what fever is, why it happens, how to manage it, and — most importantly — which specific features indicate that a child with a fever needs to be seen urgently, allows parents to respond appropriately rather than either panicking or under-responding.
Logging temperature readings and the timing and pattern of fever in Healthbooq gives you accurate information when calling for advice, and helps track whether a fever is genuinely persistent or fluctuating with medication.
What Fever Is and Why It Happens
Fever — a body temperature above 38°C — is a physiological response to infection. The immune system, detecting a pathogen, raises body temperature as part of its defensive response: many bacteria and viruses replicate less efficiently at elevated temperatures, and immune cell function is enhanced at higher temperatures. Fever is not a malfunction — it is a normal part of how the body fights infection.
The implication is that treating a fever is not the same as treating the illness. Paracetamol or ibuprofen reduce the temperature and make the child more comfortable, but they do not shorten the illness or eliminate the infection. This is why the child's overall state — how they look, whether they are drinking, how they are responding — matters more than the absolute temperature reading.
Normal body temperature varies with the method of measurement and the time of day: axillary (armpit) measurements are approximately 0.5°C lower than oral or tympanic (ear) measurements. A digital ear thermometer or a digital underarm thermometer are both practical and reasonably accurate for home use. Fever strips placed on the forehead are not reliable. Rectal measurement is the most accurate but is typically reserved for clinical settings.
Managing Fever: The Practical Approach
Paracetamol (acetaminophen) can be given from two months (to babies over 4kg weight) and is the first-line fever medication for babies and young children. The dose is weight-based: 15mg per kilogram of body weight per dose, given every four to six hours, maximum four doses in 24 hours. For a 7kg baby, this is approximately 105mg per dose — typically 3.5ml of infant suspension (30mg/ml) or 2.6ml of a 40mg/ml suspension. Always use the concentration-specific dosing instructions and a calibrated syringe.
Ibuprofen can be given from three months (to babies over 5kg) and has the advantage of an anti-inflammatory effect in addition to antipyretic and analgesic properties. The dose is 5–10mg per kilogram per dose, given every six to eight hours, maximum three doses in 24 hours. Ibuprofen should not be given to dehydrated children or those with renal impairment.
Alternating paracetamol and ibuprofen — giving one, then the other after three hours — is sometimes used for high fevers that are not well-controlled by a single agent. This is not first-line management for an uncomplicated fever but is used in practice and is safe when correct doses of each are maintained.
Cool the child with light clothing rather than thick layers that trap heat. Tepid sponging is no longer recommended as a primary fever management strategy (it can cause shivering, which raises the temperature, and is distressing for the child). Ensure adequate fluid intake — fever increases insensible water loss and dehydration can develop more quickly in febrile children.
Under Three Months: Different Rules
For babies under three months, any temperature above 38°C requires prompt medical assessment on the same day. The immune system in young babies is immature, bacterial infections can progress rapidly, and clinical signs of serious illness are less specific and harder to interpret at this age than in older children. This is a firm rule, not a guideline that is sometimes applied — a fever in a baby under three months is a medical situation that requires assessment.
Red Flag Signs at Any Age
Specific features that require urgent or emergency medical assessment regardless of the temperature reading:
Non-blanching rash (rash that does not fade under glass pressure) in a child with fever — call 999.
Difficulty breathing — fast breathing, laboured breathing, or indrawing of the chest muscles.
Persistent fever above 39°C lasting more than five days.
Fever returning after more than 24 hours of being well.
Rigors (shaking chills) not related to febrile convulsion.
A child who is very difficult to rouse, unresponsive, or has a high-pitched, unusual cry.
Severe headache with photophobia (light sensitivity) or stiff neck in an older child.
A child who cannot take any fluid by mouth.
The overall appearance of the child matters as much as any specific sign: a child with a 40°C temperature who is drinking, playing (perhaps more quietly than usual), and making eye contact appropriately is less concerning than a child with a 38.5°C temperature who is listless, refusing all fluid, and not responding to stimulation.
Key Takeaways
Fever is defined as a temperature above 38°C and is a normal immune response to infection — it is a symptom, not a disease. The goal of fever management in children is to make the child more comfortable, not to reach a specific temperature. In babies under three months, any fever above 38°C requires prompt medical assessment. In older children, the child's overall appearance and behaviour matter more than the exact temperature reading. Paracetamol or ibuprofen at the correct dose for the child's weight reduces fever and discomfort but does not treat the underlying cause. Fever that is persistent, high, or accompanied by specific red flag symptoms warrants medical assessment.
