Understanding fever in children: a friend, not an enemy...

A moderate temperature, usually between 38°C and 39°C, is considered beneficial because it helps destroy the microbes that cause illness, improves the immune response and slows the replication of pathogens. Temperatures above 40°C can be dangerous because they can cause cell damage and require medical intervention.

The body naturally regulates its temperature to optimise immune system function while minimising tissue damage, so a mild to moderate temperature is usually best for fighting infections.

Paracetamol and ibuprofen reduce fever in children, but paracetamol primarily acts on the brain's temperature regulation centre, while ibuprofen also has anti-inflammatory properties that help with pain and swelling.

Ibuprofen generally acts for longer (6–8 hours) than paracetamol (4–6 hours) and can be more effective for fever associated with inflammation. If the child's temperature does not fall after paracetamol or ibuprofen, make sure the child is well hydrated, lightly dressed and in a comfortable, cool environment. You can try alternating paracetamol and ibuprofen every few hours (following dosing guidelines) if a paediatrician recommends it.

If the temperature remains high (above 39–40°C), the child has difficulty breathing, pronounced lethargy or other worrying symptoms, seek medical help immediately.

Temperature alone cannot determine with certainty whether a child has a viral or bacterial infection, but certain patterns can offer clues.

• Viral infections often cause a moderate temperature (up to 38.5–39°C) that gradually improves.
• Bacterial infections usually cause a higher, more persistent temperature (above 39–40°C), which often worsens over time.

An accurate diagnosis nevertheless requires a clinical examination and laboratory tests.

If a child's low-grade temperature (37.1–38°C) lasts longer than 5 days, it may be caused by a prolonged viral infection (such as Epstein–Barr virus – EBV, or cytomegalovirus – CMV) or a bacterial infection (sinusitis, a urinary tract infection – UTI, or atypical pneumonia), which sometimes requires antibiotic treatment.

In some cases, a persistently slightly elevated temperature may be associated with inflammatory illnesses, autoimmune conditions or post-viral fatigue syndrome, so medical assessment is necessary.

Not all infections in children cause fever, because some mild infections may not trigger a strong immune response, particularly if the child's immune system quickly suppresses the pathogen.

• Localised infections (such as mild skin or urinary tract infections) may occur without a significant rise in body temperature.
• Immunocompromised children or newborn babies sometimes do not develop a fever even with a serious infection.

In these cases, other warning signs are important: lethargy, poor fluid intake, irritability or unusual behaviour.

Fever is not always a sign of danger, but is usually a signal that the immune system is doing its job.

The aim for parents is not to eliminate every fever, but to understand it and respond wisely.

Knowing when to support the body and when to seek paediatric help makes a significant difference to the outcome of an illness.