How reliable is axillary temperature measurement?

Aim: To assess whether axillary temperature measurements reliably reflect oral/rectal temperature measurements. Methods: This observational study compared paired axillary‐rectal and axillary‐oral temperatures in a general paediatric ward with the participation of 225 children aged ≤4 y and 112 children aged between 4 and 14 y. Results: Changes in oral/rectal and axillary temperatures correlated significantly (p < 0.0001). However, axillary temperature measurements were significantly lower than both oral (mean ‐0.56°C, SD 0.76°C) and rectal measurements (0.38°C; SD 0.76°C). Ninety‐five percent of axillary measurements fell within a 2.5–3°C range around respective paired oral/rectal measurements. The mean difference increased with increasing temperature, and was 0.4°C at low body temperatures, and over 1°C with a fever of 39°C. Neither seasonal fluctuations nor the amount of clothing worn influenced this difference. Conclusion: Axillary temperatures in young children do not reliably reflect oral/rectal temperatures and should therefore be interpreted with caution.