Understanding Baby Fever: Tips for Comforting Your Little One

One of the biggest concerns that parents have is when their baby has a fever. It is also a common reason why parents seek medical advice for their infant. A fever is not just a sign of something not being right, it’s actually your body’s way of fighting and managing an infection. We discuss the science behind fevers and the immune system, how to recognise concerning symptoms and manage a fever the next time your child has one. The information in this article is general in nature and should not replace medical advice from your own doctor.  

What is baby fever?

A fever is an elevation of the body temperature above the normal range. In babies and infants, this is when their temperature is over 38°C. A fever is not an illness itself, but an indication that the body is fighting an infection. A fever can also be the body’s normal response to other things such as teething or immunisation.

The absolute body temperature does not necessarily correspond with the severity of illness. For example, while most fevers are mild, a low grade temperature may not mean a mild illness. For newborn fever in infants younger than 3 months (over 38°C), always seek medical attention as soon as possible. For older babies seek medical advice if your infant’s fever is accompanied with other signs of being sick, for example being drowsy, difficulty breathing or vomiting, or you are concerned. 

How to take an infant’s temperature

There are a number of ways that you can measure your infant’s temperature. For babies and infants, it is recommended that you use a:

• armpit thermometer
• ear thermometer
• forehead thermometer
• rectal thermometer

A forehead and ear thermometers are less accurate in measuring fever in infants.

When taking an infant’s temperature, it is a good idea to:

• Clean the thermometer before use;
• Try to take your baby’s temperature when they are calm and not right after a bath;
• Check the instructions to make sure you are using your thermometer correctly;
• Document your readings and any symptoms, this can be helpful for any potential doctor’s appointment.

Normal infant temperature

The normal temperature for newborn babies is between 36.5 and 37.5°C but this can vary depending on where and when the temperature is taken.  Underarm (recommended for babies under 3 months) and mouth are quite accurate and easy for home measurements. In-ear & forehead digital thermometers are convenient but may not be as accurate. Check the instructions to make sure you are using your thermometer correctly.

A normal infant temperature can vary within this range depending on their age, the time of the day or activities the child has been doing. A child’s body temperature is usually lowest in the early hours of the morning and highest in the late afternoon and early evening.

What are the signs of fever in infants?

You may be able to notice the following symptoms in your baby when they have a fever.

Physical signs may include:

• Being warm to touch, especially on the forehead, back, or stomach
• Flushed or red cheeks
• Sweating or feeling clammy
• Shivering or trembling/shaking (as the fever rises)

Your infant may also be:

• Increasingly fussy or irritable
• Less active or more lethargic than usual
• Have a change in sleeping patterns (sleeping more or having trouble sleeping)
• Have a decreased appetite or refusing to eat
• Less interested in play or normal activities
• Crying more than usual or being difficult to comfort
• Have decreased wet nappies
• Refuse to breastfeed or take a bottle
• Have a dry mouth or lips

Some of these symptoms may not be as obvious in a newborn baby and you may need to keep an eye out for subtle symptoms such as being unusually quiet or are having difficulty feeding.  A fever is usually not a concern if they are still eating, drinking and playing happily.

Recognising fever in babies

To recognise when your child has a fever, you may look out for the physical signs listed above. It is also important to observe their feeding and signs of hydration, particularly in younger children. Their behaviour may also change when they have a fever.

Younger infants under 3 months of age are unable to verbalise their symptoms to you and may have more subtle symptoms. They may also have additional symptoms such as vomiting, diarrhoea, congestion, coughing, runny nose or a rash. It is therefore important to monitor them closely and look out for these signs. 

What causes fever in babies?

When viruses or bacteria invade your body, your immune system detects the threat and sends out an alarm through chemical signals. These signals reach your brain’s thermostat — the hypothalamus — which in turn raises your child’s body temperature. This increase in temperature creates an environment where many germs then struggle to survive.

But that’s not all! A fever also jumpstarts your immune system - encouraging your body to produce more white blood cells, which are like little soldiers acting to fight off the invaders. Fever also helps important immune cells, like T-cells, work faster and more efficiently by recognising germs and bugs from previous infections or immunisations.

A teething fever can be quite common. When a baby is teething, they can also experience a slight rise in temperature.  If they have a temperature above 38°C then it is more likely due to an infection and not teething.  When teething, the skin around the tooth can become inflamed and cause redness in the cheeks, this may not result in a teething fever.

When your baby has received an immunisation, the vaccine stimulates their immune system to recognize the foreign substance. Just like in an infection, the immune cells become activated and release chemicals called cytokines which can trigger a temporary increase in body temperature. This fever is actually a sign that the vaccine is working - your baby's body is building protection against the disease. These fevers are usually mild and resolve within 1-2 days.

When to take a baby to hospital with fever

A fever in infants might feel uncomfortable, with chills, aches, and sweating, but fevers are generally not harmful. That said, if your child’s fever is accompanied by other worrying symptoms that concern you, it’s important to seek medical review. Never feel silly if you are concerned, and be mindful that newborn symptoms may be more subtle than older babies.

You should also take your child to see a medical professional if: 

• Your baby is under 3 months of age and has a fever over 38°C, seek professional advice immediately.
• Your baby has a weakened immune system and a fever over 38°C you should see your GP or hospital emergency department immediately;
• Your baby has a fever that results in a rapid rise and fall of your baby’s body temperature that triggers what is known as a febrile convulsion or seizure. Seek professional help if this happens to your baby.
• They have a fever plus any of the following:
  • a high pitched scream;
  • is lethargic;
  • is reluctant to drink their milk, or eat food;
  • has an unusual rash;
  • their condition is deteriorating in any way

If seeking healthcare professional advice, it is important to provide as much information as possible, including the duration of the fever, the baby’s temperature and pictures, photos or descriptions of any other signs or symptoms you may have noticed.

How to take care of an infant with a temperature? 

When your baby has a fever, it is important to keep them cool, calm and hydrated. It is important to keep your baby comfortable and provide them with opportunities for quiet play and rest.

Dressing your baby

• Dress your baby in lightweight clothing
• Avoid dressing your baby in too many layers of clothes as exposed skin helps the body to cool.
• Use a light blanket if they feel cool
• Keep windows slightly open to allow fresh air to circulate or have a fan going. Check on them through the night when they are sleeping
• Keep the room at a comfortable temperature (not too hot)

Hydrating your baby

• Keep them hydrated – If they are under 6 months extra breastfeeds or formula (if formula-fed) may be needed. For babies over 6 months, water can be offered in addition to their usual milk feeds.
• Offer extra fluids in small amounts, more often than you usually would

Other things to do:

• Rest is best – a child with a fever will benefit from resting more than they usually would
• Use tepid water (lukewarm, not hot or cold) when bathing as cold bath water can cause their body temperature to drop too quickly
• Monitor your baby’s temperature regularly, especially if you notice their behaviour is changing or symptoms worsen.
• Give lots of cuddles and kisses to help soothe your baby at home, they’ll love the extra care and attention.
• Trust your instincts – seek medical advice if you are concerned. 

Baby fever remedies and treatment

Over the counter pain relief such as children’s paracetamol or ibuprofen can help your baby feel more comfortable. Paracetamol and ibuprofen work by helping to block the production of certain chemicals (prostaglandins) in the brain that raise body temperature. As such, they help to manage the fever, but not the underlying cause.

• Carefully follow the directions for use on the label, including the appropriate dose for your baby’s age and any warnings;
• Use the measuring device that comes with the medication for accurate dosing;
• If you are not sure, seek professional advice before giving any medication to your baby;
• Never give aspirin to children or infants.

What not to do if your infant has a fever

• Don't use cold baths or alcohol rubs – these may drop a baby’s temperature too quickly and can trigger shivering – which in turn causes the temperature to rise even more. Alcohol rubs can also be absorbed through a baby’s skin, which can lead to toxicity. Vapours from rubbing alcohol can also irritate the lungs or airways
• Don't overdress your baby or bundle them in heavy blankets
• Don't give medication more frequently than recommended on the label
• Don't give adult medications to children

Preventing fevers in babies

While you cannot prevent all fevers in babies (since fever is often a normal immune response), you can take steps to reduce the risk of infections that cause fevers:

Hand hygiene

• Wash your hands thoroughly before handling your baby
• Ask visitors to wash their hands before touching or cuddling your baby
• Keep hand sanitiser accessible for times when soap and water aren't available

Limit exposure to illness

• Avoid crowded places with your newborn, especially during cold and flu season
• Keep your baby away from people who are sick
• Ask family members with even mild symptoms to postpone their visits

Environmental cleanliness

• Regularly clean and disinfect frequently-touched surfaces
• Wash toys and other objects that your baby might put in their mouth
• Ensure proper food safety when preparing formula or baby food

Healthy home environment

• Avoid smoking around your baby (second hand smoke increases infection risk)
• Maintain good ventilation in your home
• Keep your baby's environment at a comfortable temperature
• Keep up with your baby's recommended immunisation schedule
• Ensure everyone who has close contact with your baby is vaccinated against common illnesses such as whooping cough or influenza

Immunisation

Remember that some fevers are unavoidable and even beneficial as they show your baby's immune system is working properly. The goal isn't to prevent all fevers but to minimise unnecessary exposure to infections while supporting your baby's developing immune system.

Frequently asked questions about baby fever

What is a newborn fever?

A newborn fever is when your baby's temperature rises above 38°C . Unlike in adults, even a slight fever in babies under 3 months is considered significant and requires immediate medical attention. 
A fever isn't an illness itself but rather a sign that your baby's body is fighting an infection, which could be viral, bacterial, or in some cases, a response to immunisations. 

What to do if the newborn has a fever?

If your baby has a fever, you should look for any worrying signs and seek medical attention if you are concerned. While waiting to see the doctor, keep your baby comfortably dressed in light clothing, ensure they stay hydrated with breast milk or formula, and monitor for any additional symptoms like unusual fussiness, lethargy, poor feeding, or rashes. Never attempt to reduce fever through cold baths, alcohol rubs, or other home remedies that could potentially harm your newborn.

How to take a newborn temperature?

To take a newborn's temperature, there are various thermometers you can use at home such as an armpit, mouth or ear thermometer. For an armpit measurement (recommended for under 3 month olds), place the thermometer in the centre of your baby's armpit and hold their arm down against their body to ensure an accurate reading. Ear thermometers can be used, but keep in mind that they may not provide reliable readings for newborns due to the small size of their ear canals. Always ensure that the thermometer is suitable for infants to obtain the best results.

How to dress an infant with a fever?

When your infant has a fever, dress them in lightweight, breathable clothing like a single layer onesie or light pyjamas, avoiding multiple layers or heavy fabrics that can trap heat. Remove any hats, thick socks, or blankets unless your baby feels cool to the touch or is shivering (which occasionally happens as temperature fluctuates). The goal is to allow excess body heat to dissipate naturally without causing your baby to become chilled. Keep the room at a comfortable temperature (approximately 20-22°C) with good air circulation, and check your baby's neck, chest, or back (rather than hands or feet) periodically to ensure they're not overheating or getting too cold, adjusting clothing accordingly.

When should you worry about a baby's fever?

You should worry about a baby's fever and seek immediate medical attention in several specific situations: any fever (38°C or higher) in a baby under 3 months old; a fever lasting more than 3 days in any infant; or a fever accompanied by concerning symptoms like unusual lethargy, extreme irritability, difficulty waking, refusal to feed, difficulty breathing, rash, persistent vomiting or diarrhea, signs of dehydration (decreased wet nappies, no tears when crying) or  seizures. Also concerning is if your baby looks or acts very sick regardless of the actual temperature reading, or if your parental instinct tells you something is seriously wrong.

What temperature is too high for an infant?

For infants under 3 months, any temperature of 38°C or higher is considered too high and requires immediate medical attention, regardless of how well the baby appears to be feeling. For older babies high temperatures that don't respond to fever reducers (e.g. removing layers of clothing, or having age-appropriate paracetamol) or are accompanied by other worrying symptoms warrant medical evaluation. While the absolute reading is one factor, how your baby is acting is equally important—a baby with a lower-grade fever who is extremely lethargic or showing other concerning symptoms may need more urgent care than a baby with a higher temperature who is alert and drinking fluids well.

How do I bring my baby's fever down?

To bring your baby's fever down safely, you can give weight-appropriate doses of paracetamol or ibuprofen, provided you follow your doctor's recommendations for dosage and do not exceed the instructions on the label. Keep your baby hydrated with frequent offerings of breast milk, formula, or water (if over 6 months), dress them in light clothing, and maintain a comfortable room temperature that's not too warm. A lukewarm (not hot or cold) sponge bath can help if your baby's temperature is very high, but stop if your baby starts shivering. Avoid alcohol rubs, cold baths, or ice packs, which can cause dangerous temperature drops, and never give aspirin to children.