Normal Body Temperature: A Systematic Review

PubMed was searched from 1935 to December 2017 with a variety of search phrases among article titles. The references of the identified manuscripts were then manually searched. The inclusion criteria were as follows: (1) the paper presented data on measured normal body temperature of healthy human subjects ages 18 and older, (2) a prospective design was used, and (3) the paper was written in or translated into the English language. Thirty-six articles met the inclusion criteria. This comprised 9227 measurement sites from 7636 subjects. The calculated ranges (mean +/- 2 standard deviations) were 36.32-37.76 (rectal), 35.76-37.52 (tympanic), 35.61-37.61 (urine), 35.73-37.41 (oral), and 35.01-36.93 (axillary). Older adults (age >= 60) had lower temperature than younger adults (age <60) by 0.23 degrees C, on average. There was only insignificant gender difference. Compared with the currently established reference point for normothermia of 36.8 degrees C, our means are slightly lower but the difference likely has no physiological importance. We conclude that the most important patient factors remain site of measurement and patient's age.