Do I Need Antibiotics?
Antibiotics kill bacteria. They do nothing for viruses, which cause most coughs, colds, flu and sore throats. Using them when they can’t help still brings side effects, and it breeds resistant bacteria.
Usually no antibiotics needed
- Colds, flu and COVID-19 (viruses: antivirals are a separate thing)
- Most coughs and acute bronchitis, even with coloured phlegm
- Most sore throats
- Most sinus infections, which settle within 2–4 weeks
- Many middle ear infections in children over 2, which often settle in a few days
Often needed
- Bladder infections (UTIs) and kidney infections
- Pneumonia
- Spreading skin infections (cellulitis)
- Some sexually transmitted infections
- Sepsis or a very unwell person: this is an emergency
If you’re offered antibiotics
- Ask: “Is this likely to be bacterial? What happens if I wait?”
- Sometimes a delayed script makes sense: fill it only if you’re not improving by a set day.
- Take them exactly as directed. Don’t save leftovers or share them.
- Antibiotic repeats are no longer automatic for many common antibiotics. Ask before filling a repeat weeks later.
Side effects are real
- Diarrhoea, nausea, rash and thrush are common.
- Allergic reactions can be serious. Tell every doctor and pharmacist about any past reaction.
- Each course nudges your gut bacteria towards resistance, which can make future infections harder to treat.
The bigger picture
- In 2024, 37% of Australians were dispensed at least one antimicrobial through the PBS.
- Antibiotic-resistant bacteria directly caused 1.14 million deaths worldwide in 2021, with 39 million forecast for 2025–2050.
- In 1945, Alexander Fleming warned that underdosing penicillin would breed resistant bacteria. He was right.
See your GP if
- A cough lasts more than 3 weeks, or you’re short of breath
- Fever lasts more than 3 days, or you’re getting worse instead of better
- Pain when passing urine, or pain in your side or back with fever
- A red, hot, spreading area of skin
Call 000 if someone is very drowsy or confused, has a rash that doesn’t fade when pressed, is breathing very fast, or has a racing heart with fever: possible sepsis or meningitis.
Common questions
Do antibiotics work for colds and flu?
No. Colds and flu are caused by viruses, and antibiotics only kill bacteria. They won’t speed recovery but can still cause side effects.
Does green or yellow phlegm mean I need antibiotics?
Not on its own. Coloured phlegm is common in viral infections and doesn’t mean bacteria are to blame.
Should I always finish the course?
Take antibiotics exactly as your doctor or pharmacist directs. Courses are now often shorter than they used to be. Don’t keep leftovers for next time.
What is antimicrobial resistance?
When bacteria and other germs change so medicines no longer kill them. Resistant infections are harder to treat and more likely to be serious.
What is a delayed antibiotic prescription?
A script you only fill if you’re not improving by a certain day. It avoids antibiotics for infections that clear up on their own.
What can I do for a cold instead?
Rest, fluids, paracetamol or ibuprofen if suitable, honey for cough in people over 1 year old, and time. Most colds last about 7–10 days.
Helpful resources
- Healthdirect: AntibioticsPlain-English guide from the Australian Government. Free.
Evidence and more information
- ACSQHC: Antimicrobial use in the community 2024
- Oxford NDM: GRAM study, Lancet 2024
- Nobel Prize: Alexander Fleming, 1945
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