[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Nursing](https://durgical.com/en/nursing/) › [Vital signs and assessment](https://durgical.com/en/nursing/areas/vitals/) › Measuring body temperature: sites, devices and technique # Measuring body temperature: sites, devices and technique - Assessment Temperature is taken by the route that suits the patient best, with the right technique for that route, and the route is always recorded. Updated Nov 5, 2026 ## Key points - Always record the route: rectal and tympanic read higher than oral; axillary reads lower. - Oral: wait about 15 to 25 minutes after hot or cold drinks and about 5 minutes after smoking or chewing gum. - Tympanic: straighten the canal (ear up and back in adults and children over 3; down in younger children) to avoid a low reading. - Rectal: invasive, so it is used when other routes are not appropriate; it is the most accurate route in infants. Rectal thermometers are red. - Avoid the tympanic route if an ear infection is suspected. ## What it is A temperature reading depends on where and how it is taken. Rectal and tympanic readings run higher than oral ones, and axillary readings run lower. Each route has its own technique and waiting times, and poor placement changes the reading. So nurses choose the route by the patient's age and condition, use it consistently and always record the route with the value, in degrees Celsius. ## Reference values - Adult normal ranges by route: oral 35.8 to 37.3 °C; tympanic 36.1 to 37.9 °C. - Axillary 34.8 to 36.3 °C; rectal 36.8 to 38.2 °C. - Tympanic reads about 0.3 to 0.6 °C above oral; axillary up to 1 °C below; rectal about 1 °C above. - A new temperature of 38 °C or more is an unexpected finding; below 35 °C needs medical attention at once. ## What you need - Digital thermometer with disposable probe covers: oral and axillary devices are blue, rectal ones red. - Tympanic thermometer, if available. - Water-soluble lubricant for the rectal route; gloves when there is contact with mucosa. - Knowing whether the patient recently ate, drank, chewed gum or smoked, and whether an ear infection is suspected. ## How to measure it (and why) - Choose the route by age and condition: rectal is most accurate in infants; oral, axillary or tympanic in older patients — the right route is safe and reliable. - Oral: probe in the posterior sublingual pocket, slightly off centre, mouth closed without biting — readings are reliable close to the sublingual artery. - Axillary: bare skin, probe as high in the axilla as possible, left until it beeps (about 10 to 20 seconds) — a probe that slips down reads low. - Tympanic: pull the ear up and back (down under age 3) and place the probe just inside the canal, never forcing it — this straightens the canal. - Rectal: lubricate the cover and insert 2 to 3 cm or less, by size; infants on their back, older patients on their side — this protects the mucosa. - Remove the cover, clean the device, record value in °C, route and time, and analyse it at once — the route changes how the value is read. ## How to read it - Fever is part of the immune response, but very high temperatures can damage cells and organs, and prolonged fever can dehydrate. - Older adults may have an infection with no fever: new lethargy or confusion can be the first sign. - In a patient with infection, two or more of temperature above 38 °C or below 36 °C, heart rate above 90 or respiratory rate above 20 suggest a systemic response (SIRS) and possible sepsis. - For fever, look for sweating and shaking chills, adjust the room temperature, encourage fluids and use cooling measures as ordered. ## Next step: when to call for help - Call for a new temperature of 38 °C or more, or the protocol threshold. - Call at once if the temperature is below 35 °C. - Call if fever comes with tachycardia, tachypnoea, hypotension or confusion: think sepsis. - Record the measures taken (cooling, ordered medicine) and the repeat reading. ## Test yourself Think of the answer, then tap the question to see it. ## How long do you wait before an oral temperature after a cold drink? About 15 to 25 minutes, because the drink cools the mouth and gives a falsely low reading. ## Which route usually gives the highest reading and which the lowest? Rectal gives the highest and axillary the lowest, which is why the route is always recorded. ## How do you straighten the ear canal for a tympanic temperature in an adult? Gently pull the outer ear up and back; in children under 3, pull it down. ## Which temperature route is the most accurate in infants? The rectal route, with a lubricated cover inserted gently 2 to 3 cm or less, depending on the infant's size. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/nursing/measuring-body-temperature-sites-devices-and-technique/) ## Elsewhere in DurgiPedia - [Body temperature and fever patterns](https://durgical.com/en/clinical-exam/body-temperature-and-fever-patterns/) ## Connections ## Related 1 - [Vital signs in nursing: when, how often and how to record them](https://durgical.com/en/nursing/vital-signs-in-nursing-when-how-often-and-how-to-record-them/) [← All of nursing](https://durgical.com/en/nursing/) Educational content for students; it does not replace your institution's protocols, supervised clinical training or a prescriber's order. Dose-calculation examples use made-up numbers: they are educational, not a clinical order. Sources: [Nursing Skills (Open RN), 1.3 Vital Signs](https://med.libretexts.org/Bookshelves/Nursing/Nursing_Skills_(OpenRN)/01%3A_General_Survey/1.03%3A_Vital_Signs) (Open RN, Wisconsin Technical College System (LibreTexts), 2021); [Nursing Fundamentals (Open RN), 9.7 Applying the Nursing Process (Infection)](https://med.libretexts.org/Bookshelves/Nursing/Nursing_Fundamentals_(OpenRN)/09%3A_Infection/9.07%3A_Applying_the_Nursing_Process) (Open RN, Wisconsin Technical College System (LibreTexts), 2021); [Preventing Hypothermia](https://www.cdc.gov/winter-weather/prevention/index.html) (Centers for Disease Control and Prevention, 2024). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/nursing/measuring-body-temperature-sites-devices-and-technique/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). 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