From the point of view of safety, the temperature should be measured rectally with a clinical glass thermometer in children, especially babies and young children. With oral measurement, you cannot be sure how hard the child might bite the thermometer. This could break the thermometer. The axillary measurement is also not recommended because a child cannot yet be expected to place the arm correctly and press it towards the upper body. The lack of physical contact can lead to a false measurement result.
In principle, rectal measurement is preferable for babies and small children, since an exact result can be guaranteed here. To do this, insert the tip of the thermometer with a maximum of 2 centimeters into the anus. To make insertion easier, you can put some baby oil on the tip.
If your child has persistent fever or if you have further questions about temperature measurement of children, consult your pediatrician.
Note: When taking a child's temperature, stay focused throughout the measurement