How should I measure my child’s temperature, and what counts as fever?
A temperature of 38°C or above generally indicates fever, interpreted with age and measurement method. Use a suitable digital thermometer as instructed; touching the forehead is insufficient. A baby under three months with this temperature needs urgent medical assessment.
Details
Choose an appropriate measurement site
NHS guidance recommends a digital underarm reading for young children. Other guidance uses different methods by age; readings from different sites are not interchangeable. Ear thermometers can be misleading in very young babies or when positioned incorrectly.
Reduce measurement errors
Position the tip as instructed, keep it in place until the reading finishes, and record the number, time and site. A recent bath or heavy wrapping can temporarily affect the result; wait briefly and repeat when appropriate. Do not automatically add a fixed half or full degree to every reading.
Look beyond the number
Watch breathing, feeding, alertness and urine output. A temperature falling after medicine does not rule out important illness. If the child looks seriously unwell, seek help even without a recorded high temperature or when you are uncertain about the thermometer.
Related reading: When does a child’s fever need urgent assessment or emergency care?.