We should understand why human body temperature increases sometime. Human body is aware that lots of microbes don't survive at high temperature. So, fever is first level of defense. Fevers help the body fight viruses and should only be treated if they reach 102 degrees Fahrenheit or higher and the child is uncomfortable.
Call your health care provider for a fever that does not come down despite treatment, that lasts more than 3 days, that spikes rapidly or if there is anything that you are uncomfortable with.
https://www.nlm.nih.gov/medlineplus/news/fullstory_156530.html
http://health.cua.edu/selfhelp/fever.cfm
http://kidshealth.org/parent/general/body/fever.html