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Home > Frequently Asked Questions > Temperature Measurement

Frequently Asked Questions

What causes fever?

It can be caused by a number of reasons: in most cases by infectious diseases (such as flu & pneumonia), less frequently by hormone imbalance, metabolic disorders, certain inflammatory conditions (such as rheumatoid arthritis) or even extreme sunburn or certain medications & immunizations (vaccines). 

Sometimes the cause of a fever can't be identified. If you have a temperature of 38.3 C or higher for more than three weeks & your doctor isn't able to find the cause after extensive evaluation, the diagnosis may be fever of unknown origin.

What is normal body temperature?

Normal body temperature is in the range of 36.5–37.5 °C on the average, although it varies somewhat among individuals (gender, age). Additionally, temperature can vary according to physical activities, throughout the day, & due to external factors, e.g. with the change of seasons. Normal body temperature may change during any given day. It is usually highest in the evening. Body temperature is typically elevated after physical activity.

Body temperature is a basic condition for the proper operation of the cells. It is configured by many internal organs with the control of the nervous system on the delicate balance of heat production & heat loss. This mechanism (called thermoregulation) ensures the stable operation of vital functions by keeping the body at optimum operating internal temperature.

What is my normal temperature?

Normal temperature varies with the individual & also changes depending on the time through the day.

To find out one's normal temperature, therefore we recommend performing regular measurements under the following conditions:
- Measure with the same thermometer
- Measure at the same area
- Measure at the same time of day

Click here to find out more about Omron’s range of thermometers.

Does the temperature reading depend on the body part where the reading is taken?

Yes! The most accurate optimal values derive from rectal measurement: 37.0-37.5 °C (98.6-99.5 °F), while oral measurement produces slightly lower results: 36.8° ± 0.4 °C (98.2° ± 0.7 °F). Measurements taken on the skin (armpit, ear, forehead) gives the lowest values out of these types: 36.5 °C (97.7 °F), since these correlate relatively poorly with the core body temperature.  

Click here to find out more about Omron’s range of thermometers.

What is fever?

Fever is a medical sign characterized by an increased body temperature above the normal range. Fever is not considered medically significant until body temperature is above 38°C.

Fever is caused by the release of certain chemicals by the immune system, usually as a result of an infection or inflammation. Not every fever needs medical attention, but in young children, if the temperature continues to rise or if there are other worrying symptoms, a doctor should be consulted.

Do I have to treat fever?

Fever is not by itself an illness but a defense mechanism. 

However, if it rises above 39.4 °C, some actions have to be taken to reduce it. It meant that the body is no longer able to control its inner temperature.

This can either be done by using antipyretics (medications against fever), or by taking a cooling bath. The way of treatment should be defined by a doctor, based on the underlying cause, the age & condition of the patient. Infectious diseases require anti-pathogenic drugs.

By all means, extra attention should be paid to increased water-intake, to compensate for dehydration.  

Young children with even low fever require special attention & immediate treatment aiming to reduce the body temperature (cooling bath or cold pack first, before turning to medications). 

If an infant younger than 4 months old has rectal temperature above 38 °C , immediately call your doctor or go to an emergency room, because it could be a sign of a potentially life-threatening infection.

The same action must be taken if any child has a fever above 40 °C.

Can I wipe a pencil thermometer with alcohol?

Sterilization with chemical (including alcohol) might transform the surface of the product. Do not sterilize it with any chemical.
You can clean the pencil thermometer with a cloth containing neutral detergent. 

How does the forehead thermometer MC-720 work?

This unit measures the temperature of the surface of the forehead by sensing infrared emission of the skin at the measured point & then calculates the oral-equivalent value using a unique algorithm based on actual body temperature survey data.

Why is there variance in the measurement values taken with the forehead thermometer?

- Measurements were not taken at the same location.
- The probe lens is dirty.

Why is the indicated temperature on the forehead thermometer rather high?

- The unit has been stored in a cold room. When the unit has been stored in a cold room, the measured temperature may be rather high if you measure the temperature shortly after bringing the unit to a room that is at normal temperature. Measure temperature after leaving the unit for 30 minutes in the room where it will be used. It is advisable to store the unit in the room where you are going to measure temperature.
- The probe lens has been exposed to direct sunlight.
- Measurement was taken shortly after the subject cried.
- Crying can increase facial temperature. 

Why is the indicated temperature on the forehead thermometer rather low?

- The body is sweaty. Do not use the unit when wet after swimming, bathing, or through sweating after physical exercise, as skin temperature may have fallen. Wipe away moisture & allow 30 minutes for the body to acclimatize to room temperature before measuring.
- The probe lens is dirty. Use a swab or soft cotton moistened with 70% alcohol to clean the probe lens.
- Measurement was taken in surface temperature mode. Use forehead measurement mode.
- Measurement was taken shortly after the subject was outdoors in cold weather. Wait until the forehead has warmed up.
- Measurement was taken at a location  other than the forehead.
Be sure to measure exactly at the forehead, not surrounding areas such as the hairline.

How do I disinfect my ear thermometer?

The probe is the most delicate part of the ear thermometer. For the main unit, wipe off dirt on the main unit with a soft dry cloth. Never wash the unit or clean with a cleaner containing abrasive, thinner, or benzine. 

For infrared sensor, when it gets dirty, wipe it lightly with a soft dry cloth or a cotton swab. Do not wipe the infrared sensor with a tissue paper or a towel.