A clinical thermometer is a tool for measuring temperature, designed for clinical use in humans or animals. There are a number of considerations integrated into the design of such thermometers, including the need to reduce the risk of cross-contamination between patients. Many drug stores carry ones that are designed for home use by people who want to be able to monitor their temperature. These products are also available from medical supply catalogs.
Historically, this type of thermometer was made with mercury, but this element is rarely seen in clinical use in modern times. The problem with a mercury thermometer is that the device can break, spilling mercury and posing a risk of human or animal health. Such thermometers can also be difficult to use, as they need to be held in place for several minutes, and they need to be swung to reset, as the thermometer is designed to hold the mercury in place once a maximum temperature has been reached so that the device can be taken out for an accurate reading.
Clinical thermometers can be inserted into the mouth, ear, anus, or armpit, depending on the design. Some are also designed to attach to the forehead. Given the fact that they are sometimes inserted into rather intimate locations, sterilization is important. Another important issue is calibration, as it is important to get an accurate reading when a few degrees can make a big difference. Thermometers must also be easy to use and read to ensure that people are likely to get accurate measurements.
Some companies get around the sterilization issue with single use designs. In this case, the thermometer is designed to be used on one patient and then discarded. Other companies design thermometers that can be thoroughly wiped down, and which are intended to be used with probe covers. Probe covers are disposable plastic covers that slip over the part of the thermometer being inserted, reducing the risk that microorganisms will be passed between patients.
A clinical thermometer is carefully calibrated at the time of manufacture. Some come with calibration guides that people can use to recalibrate them in their own practices, while in others cases, the thermometer can be sent back to the manufacturer. For cheaper thermometers, it can make more sense to confirm that the thermometer is not reading properly and simply discard it, rather than spending time recalibrating it.