4 months baby temperature 37.5 ℃ may be a low fever, may also be the measurement method is incorrect resulting in error, need to repeat the measurement of temperature determination. Generally, 4-month-old babies use axillary thermometry to measure body temperature, and the normal range of axillary temperature is between 36.3℃-37.3℃, with slight individual differences. Correct measurement of axillary body temperature needs to be in the baby’s quiet state and no sweat in the armpits, the measurement time is 5 to 10 minutes, this time the measurement of the body temperature error is smaller, closer to the baby’s real body temperature. If the axillary measurement of body temperature 37.5 ℃, to repeat the temperature measurement at an interval of one hour, if persistently higher than the normal range, the need for physical antipyretic treatment (such as warm water rubbing the body, etc.), if more than 38.5 ℃ will need medication (such as ibuprofen, etc.). If the 4-month-old baby 37.5 ℃, it is recommended to observe the child at the same time with or without rash, runny nose and other symptoms, if the fever does not subside, need to seek medical treatment, the drug needs to be taken under the guidance of a doctor to avoid adverse reactions.