Fever(बुखार ), also known as pyrexia and febrile response,is defined as having a temperature above the normal range due to an increase in the body's temperature set point. There is not a single agreed-upon upper limit for normal temperature with sources using values between 37.5 and 38.3 °C (99.5 and 100.9 °F).The increase in set point triggers increased muscle contractions and causes a feeling of cold.This results in greater heat production and efforts to conserve heat.When the set point temperature returns to normal, a person feels hot, becomes flushed, and may begin to sweat.Rarely a fever may trigger a febrile seizure.This is more common in young children. Fevers do not typically go higher than 41 to 42 °C (105.8 to 107.6 °F). A fever can be caused by many medical conditions ranging from non-serious to life-threatening.This includes viral, bacterial and parasitic infections such as the common cold, urinary tract infections, meningitis, malaria and appendicitis among others.Non-infectious causes include vasculitis, deep vein thrombosis, side effects of medication, and cancer among others. It differs from hyperthermia, in that hyperthermia is an increase in body temperature over the temperature set point, due to either too much heat production or not enough heat loss.
You have a fever when your temperature rises above its normal range. What's normal for you may be a little higher or lower than the average normal temperature of 98.6 F (37 C).
Depending on what's causing your fever, additional fever signs and symptoms may include:
Children between the ages of 6 months and 5 years might experience febrile seizures. About a third of the children who have one febrile seizure will have another one, most commonly within the next 12 months.
To check your or your child's temperature, you can choose from several types of thermometers, including oral, rectal, ear (tympanic) and forehead (temporal artery) thermometers.
Although it's not the most accurate way to take a temperature, you can use an oral thermometer for an armpit (axillary) reading:
Use a rectal thermometer for infants: