common childhood illnesses — symptoms, treatment, and when to worry

fever is one of the most common reasons parents seek medical advice. a fever is a temperature of 38degC or above. fever itself is not dangerous — it is the body's way of fighting infection. what matters is how your child looks and behaves, not the number on the thermometer.

gastro is an infection of the gut caused by viruses (most commonly rotavirus and norovirus), bacteria, or parasites. it causes vomiting and diarrhoea and can lead to dehydration, especially in young children. most cases resolve within a few days but dehydration is the main danger.

hand, foot and mouth disease is a common viral illness in children under 5. it causes small blisters on the hands, feet, and inside the mouth. it is extremely common in daycare and childcare settings. it is usually mild and clears up on its own within 7-10 days.

croup is a common childhood illness that causes swelling around the voice box and windpipe. it produces a distinctive barking cough that sounds like a seal. symptoms are almost always worse at night and can be frightening for parents, but most cases are mild.

bronchiolitis is a common lower respiratory infection in babies and children under 2, usually caused by RSV (respiratory syncytial virus). it causes swelling and mucus build-up in the smallest airways. most cases are mild, but it can be serious in very young babies and premature infants.

ear infections are extremely common in children — about 75% of children will have at least one by age 3. they happen when fluid builds up behind the eardrum and becomes infected, usually following a cold. they are more common in winter and in children who attend childcare.

chickenpox is a highly contagious viral illness caused by the varicella-zoster virus. it causes an itchy rash of fluid-filled blisters that appear in waves over several days. it is usually mild in children but can be more serious in babies, adults, pregnant women, and immunocompromised people. vaccination is on the National Immunisation Program.

head lice are tiny insects that live on the scalp and feed on blood. they are extremely common in primary school-aged children and spread by direct head-to-head contact. they do NOT mean your child is dirty — lice actually prefer clean hair. they are annoying but harmless.

threadworms are the most common worm infection in Australian children. they are tiny white worms (about 1cm long) that live in the gut and come out at night to lay eggs around the anus, causing intense itching. they are harmless but annoying and very easy to catch and spread.

conjunctivitis is inflammation of the thin membrane covering the white of the eye and inner eyelids. it can be bacterial (thick yellow/green discharge), viral (watery discharge, often with a cold), or allergic (itchy, watery, both eyes). bacterial and viral conjunctivitis are common in children and usually clear up without serious treatment.

impetigo is a common and highly contagious bacterial skin infection caused by staphylococcus or streptococcus bacteria. it appears as red sores or blisters that burst and develop a golden-brown crust. it is very common in warm weather and spreads easily in childcare and schools.

teething is the process of baby teeth (primary teeth) breaking through the gums. most babies start teething around 6 months, but it can start as early as 3 months or as late as 12 months. teething can cause mild discomfort but it does NOT cause high fever, diarrhoea, or serious illness — if your child has these symptoms, see a doctor.

reflux (posseting or spitting up) is extremely common in babies — more than half of all babies have some reflux. it happens because the muscle at the top of the stomach is not yet fully developed. most reflux is harmless (a 'happy spitter') and resolves by 12-18 months. GORD (gastro-oesophageal reflux disease) is when reflux causes significant problems.