Coat the base of the thermometer with petroleum jelly, and insert it slowly into the anus-only about half an inch, so that the metal part is inside. Hold the thermometer still, and, when it beeps, remove it and read the results.
[header] How to lower a baby's fever [title] Take your baby's temperature rectally. [step] If you think your baby is running a fever, use a rectal thermometer to get the most accurate results. Place your baby on his or her stomach, or on his or her back with legs pulled up.