Common illnesses in babies: What you need to know

Nothing’s more worrying than seeing your baby unwell, but you might take some comfort knowing that with immunisation rates at about 90% in Australia, there are fewer serious dangers to their health than ever before.

Illness is an inevitable part of childhood, and you’ll be kept busy at one time or another with your baby’s coughs, runny noses, fevers, rashes, and upset tummies, so we’ve put together a list of common illnesses in babies to look out for, and what you need to know.

Coughs and Colds

It’s very common for a child to get the odd cough or cold. A cough is usually caused by a cold, and will likely clear up on its own. If your baby is feeding, drinking, eating, and breathing normally, and there’s no wheezing, a cough isn’t usually anything to worry about. Coughing helps to clear away phlegm from the chest and mucus from the back of the throat.

Signs that you should see a doctor are a high temperature, the cough sounds unusual or persists, it occurs at night, or your baby is having difficulty breathing or is listless, pale, overly tired or in discomfort. If your baby has trouble breathing, seek medical attention immediately.

To find out more, you might like to read these:


Children with persistent high fevers, malaise, chills, sore throat, and cough are more likely to have the flu. Babies with colds and flu need extra cuddles and reassurance, smaller more frequent feeds, and extra sleep.

Seek urgent medical advice if your baby has a persistent cough, difficulty breathing, a high fever (see a doctor immediately for any fever in a baby under 3 months), bluish or pale skin, inability or unwillingness to feed, drowsiness, isn’t drinking, is vomiting a lot, or has a rash that doesn’t disappear when you press on it.

Prevention is an option:

Middle ear infections

While there are many different types of ear infections, a middle ear infection is the most common, with babies and children being the most prone to them. Ear infections can be caused by either bacteria or viruses, and signs to look for might be your baby rubbing or pulling at their ear, having a temperature of 38℃ or above, having redness around their ear, being restless or irritable, and not responding to sounds that would normally attract their attention.

See your doctor if your baby is in pain, there is discharge from their ear, they’re vomiting, can’t hear properly, there is swelling behind the ear, or your baby keeps getting ear infections.


Croup is very common and is usually not serious. The inflammation is usually caused by the same viruses that cause the common cold. It causes swelling of the windpipe, the airways to the lungs, and the vocal cords. A child with croup has a distinctive barking cough and may make a harsh sound, known as stridor, when they breathe in. It’s often a mild illness but can become serious quickly.

Croup can be a frightening experience for any parent, but knowing the tell-tale signs can help ease the fright and help you get the right treatment for your baby:

Vomiting and Diarrhoea

It can be very concerning to see your baby having bouts of vomiting or diarrhoea. Either can can be caused by many different things including a virus, a stomach bug, food poisoning, or they’ve eaten something they may be allergic to.

The main treatment for diarrhoea and vomiting is to keep your baby at home, and ensure they keep drinking fluids such as breastmilk or formula. It’s more serious in babies than older children because babies can easily become dehydrated. Signs of dehydration are: lethargy, fewer wet nappies, dark yellow urine, a dry mouth, sunken eyes, a sunken soft spot on their head, and few or no tears when they cry.

Babies under 6 months old should always be checked by a GP if they have vomiting and diarrhoea, and all babies should see a GP if they’re not drinking, the diarrhoea doesn’t improve after 10 days, they can’t keep any fluids down, they’re dehydrated, they have blood in their poo, or they have green vomit.

Read more advice here:

Whooping cough

Whooping cough (also known as ‘pertussis’) is a highly infectious infection of the lungs and airways, and is caused by a bacteria. The disease is most serious in babies under 12 months, particularly in the first few months.

It is recommended that all pregnant women receive a pertussis vaccination during each of their pregnancies, usually around the 28 week mark, but can be given any time. Your baby will be immunised against it but won’t have full immunity until the third dose of the vaccine at 6 months.

Read everything you need to know about the whooping cough vaccine here:

Viral Rashes

Rashes are very common in babies, and most are caused by common viral infections and are nothing to be worried about. Usually they go away on their own. Rashes can have many different appearances including: red, flat areas; raised bumps: blisters; welts; or any combination of these. It may spread to most or all parts of the body, and can last for days or weeks.

Most rashes are mild and won’t cause your baby distress, although some can cause a lot of itching. Viruses that cause a rash are: chickenpox; measles; hand, foot, and mouth disease; Henoch-Schönlein purpura; Molluscum; Roseola infantum; and Slapped cheek.

(See the fact sheets for each of these viruses on the Royal Children’s Hospital website)

Often the viral infection causing the rash will also cause your baby to have a fever, which usually happens at the start of the illness, before the rash appears. If your baby has a rash and a fever, see your GP immediately.

Other Rashes

Most babies experience a rash at one time or another, and many disappear without treatment. While viral rashes may be accompanied by a fever, itching, and other symptoms, some of the more common rashes with no fever or itching include: Newborn baby acne, erythema toxicum (blotchy red skin in newborns), nappy rash, keratosis pilaris (‘chicken skin’). Rashes that might be itchy include: eczema, ringworm, heat rash, and hives.

Many babies develop a rash in their first days or weeks as their sensitive skin adapts to a new environment. But if your baby seems unwell, or you’re worried, you should see your doctor. They can advise about the cause and whether any treatment is necessary.

Find out more about some of these rashes here:

Allergies and Asthma

Hayfever, asthma, and anaphylaxis are all common conditions that are triggered by allergies when children are exposed to animals, dust mites, pollen, insect bites, and foods including nuts, eggs, seafood, and dairy products.

Asthma is difficult to diagnose in children under 5, so speak to your GP who will undertake a medical history and ask about your child’s symptoms. For more information, go to Asthma Australia about diagnosis. To learn more about food intolerances and allergies, you might like to read the following articles:

A final word on common baby illnesses

You know your baby better than anyone, so never be concerned that you’re wasting your doctor’s time, or that you might seem like you’re being an anxious and overprotective parent…that’s your job, so don’t hesitate to seek medical advice day or night if you’re concerned about your baby’s health.



Pregnancy, Birth, & Baby

Health Direct

Royal Children’s Hospital

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