A normal, healthy person has a body temperature around 37 degrees Celsius. When our body is invaded by virus or bacteria, the immune system raises our body temperature to fight the infection, resulting in a fever.
A fever can happen suddenly and it may not be easy to pinpoint its cause.
Look out for these illnesses and their accompanying symptoms, which tend to cause fever in children:
- Upper Respiratory Tract Infections (Common Cold): sore throat, stuffy nose, cough
- Gastroenteritis(Stomach Flu): vomiting, diarrhoea, stomach ache
- Influenza(Flu): headache, chills, muscle aches, general fatigue, cough, sore throat
- Hand, Foot and Mouth Disease: blister-like rash on the palms, soles, buttocks, tongue and mouth
- Dengue Fever: headache, muscle and joint aches, rash
- Chickenpox: blister-like rash on the body
- Kawasaki Disease: red eye, body rash, swollen lips, tongue, feet, hands, lymph nodes in the neck
A recent vaccination may bring about a low-grade fever, but teething in babies usually does not cause fever.
Measuring the body temperature
Choose a thermometer that is easy to use depending on the age of your child:
- Digital thermometers (for ears, temple, forehead): These are non-invasive and easy to use on young children, even when they are asleep.
- Digital oral thermometers: Your child needs to be able to keep still and hold the thermometer in his mouth long enough to take a reading. A digital oral thermometer is relatively cheap and easy to use, and provides accurate readings. Do note that a reading taken under the armpits is less accurate.
- Rectal thermometer: This gives the most accurate reading but is invasive and less convenient to use.
Do not use a mercury thermometer for children under six in case of breakage leading to mercury poisoning.
A temperature between 37.5 to 37.9 degrees Celsius is a low-grade fever, and a temperature above 38.5 degrees Celsius is high fever.
To help your child feel more comfortable, here's what you can do to bring down his temperature:
- Sponge him with lukewarm water. Do not sponge your child with ice water or cold water, or for more than 30 minutes at a time.
- Dress your child in thin clothing and cool the room. Do not wrap him in thick blankets to “sweat it out” as it will prevent him from losing heat.
- Let your child rest more and drink lots of fluids to avoid dehydration.
- Seek medical advice and take the prescribed dosage of fever medication like paracetamol and ibuprofen (provided your child has no allergies) if his fever remains above 38.5 degrees Celsius. Do not give your child aspirin.
When Should You Bring Your Child to the Doctor?
Fever can be scary, especially if your child is very young, or if his fever is persistently high for a few days. Very high fever in children may cause febrile fits but rarely do high fever and febrile fits lead to brain damage.
A higher temperature does not mean a more severe illness. Fever is a symptom of an underlying disease and a sign that the body is fighting the disease.
Depending on your child's age, look out for changes in his behaviour when deciding whether and when, to bring him to the doctor.

If your child appears well and is able to take feeds or eat despite running a fever, let him rest and sponge him to keep his temperature below 38 degrees Celsius.
However, if your child has a fever and shows the following signs, bring him to the doctor:
- not eating well or unable to keep food down due to vomiting
- has difficulty breathing
- is lethargic and drowsy
- looks sicker than previously
- has abdominal pain and discomfort
- has a rash
- is dehydrated (e.g. not passing enough urine)
You should also bring your child to the doctor if:
- your baby is below three months old and has a fever above 38 degrees celsius
- your baby is below one year old and has a fever for more than 24 hours, or has a high fever
- your child is above one year old and has a high fever for more than three days
Reference: HealthHub