A brief report on the normal range of forehead temperature as determined by noncontact, handheld, infrared thermometer

Ng, Daniel Kwok-keung; Chan, Chung-hong; Chan, Eric Yat-tung; Kwok, Ka-li; Chow, Pok-yu; Lau, Wing-Fai; Ho, Jackson Che-Shun

BACKGROUND: Noncontact forehead temperature measurement by handheld infrared thermometer was used as a screening tool for fever. However, the accuracy data and normal range of forehead temperature determined by this method were not available. METHODS: The temperature readings from 3 handheld infrared thermometers were validated against an electronic thermometer. Normal range of forehead temperature was determined by measuring the forehead temperature in 1000 apparently healthy subjects. RESULTS: Significant differences were detected in readings obtained by the 3 different handheld infrared thermometers (analysis of covariance, P < .001) The most accurate one was chosen, and the normal range of forehead temperature in 1000 subjects detected by this method was 31.0°C to 35.6°C. CONCLUSIONS: Our study shows that commercially available, handheld infrared thermometers require individual validation. Forehead temperature in excess of 35.6°C is suggestive of fever. Further studies are required to confirm accuracy of this value in detecting fever.