[header] How to use a rectal thermometer [title] Look for symptoms of a fever. [step] Keep in mind that young children and infants may not exhibit these symptoms. Fever symptoms include : [substeps] Sweating and shivering headache muscle aches loss of appetite general weakness hallucinations, confusion, irritability, convulsions, and dehydration may be present with high fevers. 
[title] Consider the age, health condition, and behavior of the child or elderly person. [step] For babies younger than 3 months, taking the temperature rectally is most recommended.