The temperature can be measured in various locations on the body which maintain a fairly stable temperature (mainly sub-lingual, axillary, rectal, vaginal, forehead, or temporal artery). The normal temperature varies slightly with the location; an oral reading of 37 °C does not correspond to rectal, temporal, etc. readings of the same value. When a temperature is quoted the location should also be specified. If a temperature is stated without qualification (e.g., typical body temperature) it is usually assumed to be sub-lingual. The differences between core temperature and measurements at different locations, known as clinical bias, is discussed in the article on normal human body temperature. Measurements are subject to both site-dependent clinical bias and variability between a series of measurements (standard deviations of the differences). For example, one study found that the clinical bias of rectal temperatures was greater than for ear temperature measured by a selection of thermometers under test, but variability was less.
Oral temperature may only be taken from a patient who is capable of holding the thermometer securely under the tongue, which generally excludes small children or people who are unconscious or overcome by coughing, weakness, or vomiting. (This is less of a problem with fast-reacting digital thermometers, but is certainly an issue with mercury thermometers, which take several minutes to stabilise their reading.) If the patient has drunk a hot or cold liquid beforehand time must be allowed for the mouth temperature to return to its normal value.
The typical range of a sub-lingual thermometer for use in humans is from about 35 °C to 42 °C or 90 °F to 110 °F.
The armpit (axilla) temperature is measured by holding the thermometer tightly under the armpit. One needs to hold the thermometer for several minutes to get an accurate measurement. The axillary temperature plus 1 °C is a good guide to the rectal temperature in patients older than 1 month. The accuracy from the axilla is known to be inferior to the rectal temperature.
Main article: Rectal thermometry
different test prods (top: universal test prod, bottom: rectal test prod)
Normal Thermometer temperature-taking, especially if performed by a person other than the patient, should be facilitated with the use of a water-based personal lubricant. Although Normal temperature is the most accurate, this method may be considered unpleasant, or embarrassing in some countries or cultures, especially if used on patients older than young children; also, if not taken the correct way, Normal temperature-taking can be uncomfortable and in some cases painful for the patient. Normal temperature-taking is considered the method of choice for infants
The ear thermometer was invented by Dr. Theodor H. Benzinger in 1964. At the time, he was seeking a way to get a reading as close to the brain's temperature as possible, since the hypothalamus at the brain's base regulates the core body temperature. He accomplished this by using the ear canal's ear drum's blood vessels, which are shared with the hypothalamus. Before the ear thermometer's invention, easy temperature readings could only be taken from the mouth, rectum or underarm. Previously, if doctors wanted to record an accurate brain temperature, electrodes needed to be attached to the patient's hypothalamus.
This tympanic thermometer has a projection (protected by a one-time hygienic sheath) that contains the infrared probe; the projection is gently placed in the ear canal and a button pressed; the temperature is read and displayed within about a second. These thermometers are used both in the home and in medical facilities.
There are factors that make readings of this thermometer to some extent unreliable, for example faulty placement in the external ear canal by the operator, and wax blocking the canal. Such error-producing factors usually cause readings to be below the true value, so that a fever can fail to be detected.
A temporal artery thermometer, which uses the infrared principle report temperature, were not very accurate and therefore caution should be used.
The band thermometer is applied to the patient's brow. It is typically a band coated with different temperature-sensitive markings using plastic strip thermometer or similar technology; at a given temperature the markings (numerals indicating the temperature) in one region are at the right temperature to become visible. This type may give an indication of fever, but is not considered accurate.