Antibiotics: when they help—and when they do not

Different germs need different tools

Antibiotics treat certain infections caused by bacteria. They do not work against viruses such as those responsible for colds or influenza, and many sore throats and cases of bronchitis are viral. Even some bacterial infections can improve without antibiotics, depending on the illness and the person.

Symptoms and mucus colour alone do not reliably reveal which germ is responsible. A clinician considers the pattern of illness, examination findings, risk factors and sometimes testing before deciding whether an antibiotic is likely to help.

Unnecessary use has real costs

When antibiotics are not needed, they cannot speed recovery from a viral infection. They can still cause side effects, including nausea, diarrhoea, rash, yeast infection and, less commonly, serious allergic reactions or other complications. Antibiotic exposure also contributes to antimicrobial resistance, in which germs become harder to treat.

Resistance does not mean a person's body has become resistant. It means bacteria or other microbes have changed. Resistant infections can spread between people, so appropriate antibiotic use is both an individual safety issue and a shared public-health responsibility.

• Take an antibiotic exactly as prescribed for you.
• Do not save leftovers or share them with someone else.
• Ask what the medicine is treating and what side effects to watch for.
• Use a medicine take-back option or ask a pharmacist about disposal.

Good care is not always a prescription

When an antibiotic is not appropriate, a clinician can still discuss symptom relief, expected recovery and signs that the illness should be reassessed. Hand hygiene, covering coughs, staying away from others when unwell and recommended vaccination can help reduce infections and their spread.

This article is general education, not a diagnosis or a recommendation to start, stop or select an antibiotic. New or worsening symptoms and possible medicine reactions should be assessed by a qualified healthcare professional.