From the Guidelines
The normal range for adult normothermia is between 36°C and 37°C, with a target range of 36.5°C to 37.5°C. This range can vary slightly throughout the day due to natural circadian rhythm fluctuations, with temperatures usually lower in the morning and higher in the evening 1. Factors such as physical activity, environmental conditions, menstrual cycles in women, and the method of measurement can also affect body temperature. Oral temperatures tend to be about 0.5°C lower than rectal temperatures, which are considered the most accurate. Core body temperature is tightly regulated by the hypothalamus in the brain, which acts like a thermostat to maintain homeostasis. Temperatures above 38°C are generally considered febrile (fever), while those below 36°C may indicate hypothermia. Understanding your normal baseline temperature can help you better recognize when you might be experiencing a fever or other temperature abnormality.
Some key points to consider:
- The European guideline on management of major bleeding and coagulopathy following trauma recommends targeting normothermia with core temperatures between 36 and 37 °C to create optimal pre-conditions for coagulation 1.
- The Society of Critical Care Medicine and the Infectious Diseases Society of America guidelines for evaluating new fever in adult patients in the ICU define fever as a single oral temperature measurement greater than or equal to 38.3°C 1.
- The 2024 American Heart Association and American Red Cross guidelines for first aid provide a table on hypothermia signs, symptoms, and potential rewarming strategies, but do not specifically define the normal range for adult normothermia 1.
- The European Resuscitation Council and European Society of Intensive Care Medicine 2015 guidelines for post-resuscitation care discuss targeted temperature management, but do not provide a clear definition of the normal range for adult normothermia 1.
Overall, the most recent and highest quality study suggests that the normal range for adult normothermia is between 36°C and 37°C, with a target range of 36.5°C to 37.5°C 1.
From the Research
Normal Range for Adult Normothermia
The normal range for adult normothermia is a topic of ongoing research and debate. According to various studies, the normal range for adult normothermia can be summarized as follows:
- Oral temperature: 35.73-37.41°C 2, with a mean temperature of 36.1°C (97.0°F) 3
- Rectal temperature: 36.32-37.76°C 2
- Tympanic temperature: 35.76-37.52°C 2
- Urine temperature: 35.61-37.61°C 2
- Axillary temperature: 35.01-36.93°C 2
Factors Affecting Normal Body Temperature
Several factors can affect normal body temperature, including:
- Age: Older adults (age ≥60) tend to have lower temperatures than younger adults (age <60) by 0.23°C, on average 2
- Sex: There is only an insignificant gender difference in normal body temperature 2
- Time of day: Temperature can vary throughout the day, with higher temperatures typically occurring in the evening 3
- Individual variability: Normal body temperature can vary significantly from person to person, with some individuals having a lower normal temperature than others 3, 4
Clinical Implications
The normal range for adult normothermia has important clinical implications, particularly in the diagnosis and management of fever and hypothermia. For example: