A 15 month old child presented to A&E with a temperature of 39.2°C. On examination she was fully conscious, tachycardic, and tachypnoeic. Examination revealed crepitations at the left base. A chest x ray confirmed the presence of a left lower lobe pneumonia. She was commenced on intravenous cefuroxime; initial results revealed white cell count 19.1×10⁹/l (neutrophilia) and C reactive protein 126 mg/l.

On arrival to the ward she was found to be hypothermic (33.6°C). She had received paracetamol (15 mg/kg) and ibuprofen (5 mg/kg) in A&E. She had not been unduly exposed. This was her first presentation to hospital. In view of hypothermia with obvious sepsis a lumbar puncture was performed to rule out CNS involvement. This was entirely normal. Despite warming techniques she remained cool for the next 11 hours (fig 1).

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Figure 1

 Temperature chart of the first hours following admission.

Prolonged hypothermia provoked investigation of central causation. Thyroid function tests, cortisol, and computed tomography were normal. She recovered from her pneumonia and has been entirely well since.

In view of the temporal link between the antipyretics and the fall in temperature, it seems appropriate to consider causation. Both paracetamol and ibuprofen have previously been linked individually to hypothermia.^1,2 Logically, giving both together may have a summative effect on decreasing temperature. Currently there seems to be a great hurry to “treat temperatures”, often using high doses of paracetamol combined with ibuprofen to reach the magic 37°C. However, the risks and benefits of fever should be weighed up. Fever induces host defence mechanisms preventing multiplication of organisms, but can also lead to febrile convulsions and increased cardiovascular demands.

Antipyretics are not without their problems and hypothermia may be one of these. Is hypothermia bad for you? Probably not in the short term, but generally we are not trying to induce it.

A recent case also describes hypothermia following a single dose of ibuprofen. This had a duration of four days.³ Ibuprofen has a half life of 2 hours and is unlikely to have such a prolonged effect. Hypothermic sepsis is uncommon in paediatrics but must also be considered in both cases.⁴ It is important to note that in neither case was a causal organism identified.