Before we discuss how to measure your client’s temperature, we need to cover some definitions. Our body is always generating heat through metabolism, and a part of the brain, called the hypothalamus, tries to keep the core body temperature constant like a thermostat. When we are febrile, meaning we've got a fever, the thermostat is raised higher, and this can be due to an infection, inflammation, or cancer. However, body temperature could also be high in hyperthermia (Fig. 2), where the thermostat is set at the right temperature, but the body simply can’t get rid of the heat. This can be due to an extremely hot environment, excessive exercise, and reduced sweat production. In contrast, hypothermia (Fig. 2) is when body temperature gets too low, and it might be due to exposure to cold for a prolonged period of time, either accidentally or in preparation for a medical procedure.

• if the client has been coughing, sneezing, eating, drinking, smoking, or chewing gum in the past 15 minutes (Fig. 3) 
• if the client is receiving oxygen therapy with a face mask, because this can interfere with the results 
• for clients who are unable to hold the thermometer tightly in their mouth, like those who are unconscious, have undergone a jaw or mouth injury or surgery, or have trouble breathing through their nose
• for clients who might bite the thermometer, like those who are likely to have a seizure and children under five 

• an electronic thermometer
• a blue oral probe 
• a probe sheath

1. Ask the client to open their mouth before inserting the thermometer into one of their posterior sublingual pockets at the base of the tongue, not in front of it (Fig. 3b). 
2. Ask them to keep their lips closed and breathe through their nose (Fig. 3c). 
   • You typically need to wait for 20–30 seconds.
   • Most electronic thermometers also chime when they're done.
3. Ask the client to open their mouth and take the thermometer away (Fig. 3d). 
4. The temperature will be visible on the screen.
5. You can then push the button on the probe to detach the probe sheath and discard it in the appropriate manner (Fig 3d). 
6. Finally, practice hand hygiene and make sure the thermometer is ready to be used again by putting away the probe, switching the thermometer off, and connecting it back with its charger.

If the client is comatose, confused, critically ill, in a shock, or unable to close their mouth, obtaining a rectal temperature would give the most accurate measurement. The rectal temperature is normally 0.7–1°F (0.4–0.5°C) higher than the oral temperature. This means it should be between 98.6–100.6°F (37–38.1°C) for adults, and 98–100°F (37–38°C) for children. 

However, this method is often uncomfortable, both physically and emotionally, and it’s also riskier than the other methods. It should be avoided in clients with hemorrhoids, diarrhea, lesions around the anus, or those who have recently had surgery involving this region. Furthermore, the thermometer can stimulate the vagus nerve found inside the rectum, which could trigger a reflex that slows down the heart rate and lowers blood pressure, so clients with heart conditions should also avoid this procedure.  

• gloves 
• paper towels 
• tissues 
• a lubricant jelly 
• an electronic thermometer 
• a red rectal probe 
• a probe sheath 

1. Start by practicing hand hygiene, help the client roll over into Sims' position with the upper leg bent, and adjust the linens and the clothing to expose the area of the buttocks. Through all this, make sure to respect the client’s privacy. Then, check that the wheels on the bed are locked. Raise the bed to a comfortable working height (Fig. 4b). 
2. For the electronic thermometer, attach the red rectal probe stem to the thermometer, slide the sheath over the probe, switch it on, and check for a ready sign on the screen. 
3. Leave the thermometer on a clean paper towel on the over-bed table. Place some of the lubricant on the paper towel and then apply plenty of it on the tip of the thermometer to help it get inserted more smoothly. 
4. Lower the side railings on the side you’re working on. Wear gloves and, with one hand, separate their buttocks. Ask them to breathe slowly and relax. 
5. Insert the lubricated probe about three cm, or a little over an inch, deep in the direction of the umbilicus (Fig. 4c). 
   • Make sure to stop and don’t force it if you feel resistance. 
   • Hold the electronic thermometer for 20–30 seconds or until it chimes (Fig 4d).
6. Remove the thermometer, use a tissue to clean the area of the buttocks, and readjust the linens as well as the client’s clothing. 
7. Remove the sheath with a tissue and discard both the tissue and the sheath. 
8. Note the temperature on the screen of the electronic thermometer. 

You can then remove your gloves and practice hand hygiene. Return the side rails to the raised position, adjust the height and head of the bed, help the client move back into a comfortable position, and make sure that the wheels are locked. Finally, the thermometer needs to get ready for its next use, so, for an electronic thermometer, switch it off, put away the probe, and thoroughly clean and sanitize it before putting it on charge. 

The tympanic membrane thermometer, or TMT, measures the temperature from a client’s eardrum. It’s almost as accurate as rectal temperature if done properly, but accuracy might be affected by ear infections, like otitis media or a buildup of cerumen, or earwax. A normal tympanic membrane temperature is 98.6°F (37°C) for adults and 98–100°F (37–38°C) for children. 

• a tympanic thermometer
• a tympanic probe sheath

1. First, practice hand hygiene and check if the client is using a hearing aid; if they are, slowly take it away and wait for a couple of minutes before proceeding (Fig. 5b).
2. If there is too much earwax, use a warm, moist washcloth to carefully wipe the ear canal. 
3. Slide a probe sheath over the thermometer’s probe (Fig. 5c) before holding the thermometer with your dominant hand. Place the probe tip in their ear canal, pulling the pinna back and up for an adult or straight back for a child (Fig. 5d).
4. Applying gentle pressure, aim the probe towards the client’s nose so that the beam gets to the tympanic membrane. 
   • Make sure you’re not blocking the canal.
   • Press the scan button and remove the thermometer when you hear the chime, usually after one second. 
   • Take the thermometer away and read the temperature on the screen. 
   • Push the button on the side to detach the probe sheath and discard it in the appropriate manner (Fig. 5d).
5. Finally, practice hand hygiene and make sure the thermometer is ready to be used again by switching it off and connecting it back with its charger if needed.

This method is the safest but the least accurate. You can use it on newborns or unconscious people if other methods cannot be obtained. A normal axillary temperature falls between 96.6–98.6°F (36–37°C) for adults and 96–98°F (35–36°C) for children. 

• paper towels and tissues 
• an electronic thermometer 
• a blue oral probe 
• a probe sheath 

1. Ask the client if they have bathed or used an antiperspirant or deodorant in the past 15 minutes. If they have, wait 15–30 minutes before proceeding. 
2. Make sure to practice hand hygiene and prepare the electronic thermometer by attaching it to the blue oral probe stem, sliding the sheath over the probe, switching it on, and checking for a ready sign on the screen (Fig. 6b). 
   • For a chemical dot thermometer, simply slide the cover sheath. 
3. Help the client expose their arm from their clothing. Use a paper towel to softly dry the axilla (Fig 6c). 
   • You can now lift up their arm to reveal the axilla; center the probe in the axilla and fold the arm over and onto the client’s chest. 
   • Ask the client to hold it in place until you hear the electronic thermometer chime, or for three minutes if it’s a chemical dot thermometer (Fig 6d). 
4. Assist them with lifting their arm up again and take the thermometer.
5. Read the measurement. 
   • For an electronic thermometer, see the temperature on the screen and discard the probe sheath. 
   • For a chemical dot thermometer, see the last blue dot on the matrix.
6. Assist the client back into their clothing and a comfortable position. Finally, switch the electronic thermometer off, put away the probe, and put it on charge. If you’ve used a single-use chemical dot thermometer, discard it; otherwise, you can put a reusable one back into its case.

• a temporal artery thermometer 
• a towel 
• alcohol wipes 

1. Practice hand hygiene, brush any hair away, and use a towel to softly dry the forehead. 
2. Place the sensor on the forehead, hold down the scan button, and slide it steadily across the forehead. 
3. Read the temperature on the screen. 
4. Practice hand hygiene and make sure the thermometer is ready to be used again by switching it off, cleaning the sensor with alcohol wipes, and connecting it back with its charger.

• the date and time that you did the procedure 
• the temperature reading 
• the method with which it was taken 
• your observations 
  • Common abbreviations: “O” is for oral, “R” for rectal, “T” for tympanic, and “A” for axillary