Antibiotics are among the most prescribed medicines for children, but a sizeable share of those prescriptions are written for viral illnesses that antibiotics cannot touch. Understanding when antibiotics genuinely help — and when watchful waiting and good symptom management are the right answer — leads to better conversations with your GP, fewer side effects for your child, and less pressure on a system already struggling with resistance.
The point isn't that antibiotics are dangerous when they are needed. The point is that when they aren't needed, the prescription brings risk without benefit, and the benefit is what was at stake.
Healthbooq supports parents with evidence-based guidance on common childhood illnesses, including when antibiotics are genuinely indicated and how to manage viral illness well at home.
Antibiotics: What They Do and Do Not Do
Antibiotics kill or stop the growth of bacteria. They do nothing to viruses — and viruses cause the bulk of children's respiratory and gut illnesses. Giving an antibiotic for a viral illness will not shorten the cold, will not stop your child from being contagious, and will not prevent a bacterial complication in most cases. What it will do is expose them to side effects and add a tiny push towards resistance.
The most common illnesses in children under 5 — colds, the majority of sore throats and coughs, bronchitis, most ear infections, and gastroenteritis — are viral the great majority of the time. Their natural course is recovery within 7–14 days. Antibiotic treatment doesn't change that.
Common Childhood Illnesses: Antibiotic Decision-Making
Sore throat (pharyngitis and tonsillitis). About 80% are viral. Group A Streptococcus accounts for the rest and does respond to antibiotics — penicillin V is first-line in the UK, typically 250 mg twice or three times daily for 10 days in young children. The Centor and McIsaac criteria help GPs work out who is more likely to have strep, and a throat swab or rapid antigen test confirms it. Most UK GPs will not prescribe for sore throat without evidence of bacterial cause.
Ear infections (acute otitis media). Around 60% are viral. NICE recommends watchful waiting for most children, with paracetamol or ibuprofen for pain. A delayed (back-pocket) prescription if symptoms haven't settled in 2–3 days is a useful approach. Antibiotics shorten pain modestly in bacterial cases, but most ear infections clear without them. Children under 2 with infection in both ears, those with ear discharge, or those who are systemically unwell are more likely to be offered antibiotics from the start. When prescribed, amoxicillin 80–90 mg/kg/day in two divided doses for 5–7 days is standard.
Coughs and chest infections. Most acute coughs in children follow a viral upper respiratory infection. Bacterial pneumonia does need antibiotics; most coughs do not. A cough that has produced sputum for days, has gone past three weeks, comes with high fever, or comes with fast or laboured breathing (over 50 breaths per minute in a 1–5 year old, or chest indrawing at any age) deserves an assessment — but assessment doesn't automatically lead to a prescription.
Conditions that do need antibiotics. Urinary tract infections, impetigo, confirmed Group A strep throat, bacterial pneumonia, whooping cough (pertussis), Lyme disease, cellulitis, and any child unwell enough to be admitted.
Side Effects and Risks of Unnecessary Antibiotics
Antibiotics disrupt the gut microbiome — the community of bacteria in the bowel that helps with immune training, vitamin synthesis, and digestion. Repeated early exposure has been linked in long-term cohort studies to higher rates of obesity, asthma, and allergic disease, though the precise contribution of antibiotics versus the underlying infections is still being worked out. Short-term side effects show up immediately: amoxicillin causes loose stools or diarrhoea in up to 10–15% of children, skin rashes are common, and oral thrush or nappy-area thrush from Candida overgrowth follows in some.
Antibiotic resistance — bacteria that survive normal doses of standard antibiotics — is one of the major public health threats of this century, according to the CDC and WHO. Every unnecessary prescription contributes to the selection pressure that produces resistant strains.
When Antibiotics Are Prescribed: Completing the Course
If your GP does prescribe antibiotics, finish the course as directed — even if your child seems back to normal in three days. Stopping early can leave the more antibiotic-tolerant bacteria behind to multiply. Course lengths are based on evidence about what reliably clears the specific infection: 5–7 days for most cases of acute otitis media, 5–7 days for community-acquired pneumonia in children, 10 days for strep throat, 3–7 days for an uncomplicated UTI. Modern guidance favours shorter courses where evidence supports them, but follow what your prescriber wrote.
Key Takeaways
Antibiotics treat bacterial infections and have no effect on viruses, which cause most common childhood illnesses including colds, most sore throats, most ear infections, most chest infections, most coughs, and gastroenteritis. Unnecessary antibiotic use exposes children to side effects (diarrhoea, rash, thrush), disrupts the gut microbiome, and adds to antibiotic resistance. When antibiotics are genuinely needed, finishing the prescribed course matters. Parents who understand the difference between bacterial and viral illness are less likely to expect or push for an unnecessary prescription.
