Antibiotics: when they help and when they do nothing
Most sore throats and colds are viral
Dr. Yanis Kaddour
Infectious disease specialist
In simple terms
Taking antibiotics for a virus brings side effects without any benefit.
Bacteria versus viruses
Antibiotics kill bacteria. They have no effect whatsoever on viruses. Colds, most sore throats, most coughs, flu and COVID are viral, which is why an antibiotic will not shorten them.
Green mucus is not proof of infection
The colour comes from immune cells doing their job and appears in ordinary viral colds. It is not by itself a reason for antibiotics.
When antibiotics are genuinely needed
- Confirmed streptococcal throat infection
- Bacterial pneumonia
- Urinary tract infection with symptoms
- Skin infections such as cellulitis
- Any severe infection with high fever and rapid deterioration
Why misuse matters to you personally
Beyond resistance across the population, each course disturbs your own gut flora for weeks, can cause diarrhoea, thrush and allergic reactions, and makes a resistant infection more likely for you specifically in the following months.
Finish the course as prescribed
Follow the length your doctor set for your infection, and never reuse leftover antibiotics from a previous illness or from someone else.
The words explained
Medical terms used above, in everyday language.
- Symptom
- A sign you can feel or see that something is wrong, like pain, tiredness or a rash.
- Immune system
- Your body's defence team: cells that fight germs and repair damage.
- Antibiotic
- A medicine that kills bacteria. It does not work against viruses like colds or flu.
When should you see a doctor?
- Your symptoms last more than a few weeks or keep coming back.
- They get worse quickly, or stop you doing everyday things.
- You notice sudden pain, breathing trouble, fainting or bleeding — seek urgent care.
- You already take medication and want to change anything about it.
This article explains general health information. It does not replace advice from your own doctor.
Frequently asked questions
- What is Antibiotics: when they help and when they do nothing?
- Taking antibiotics for a virus brings side effects without any benefit.
- What are the main symptoms or signs of Antibiotics: when they help and when they do nothing?
- Common signs vary from person to person. The article above lists the symptoms to watch for, how they progress, and when they need medical attention.
- When should you see a doctor for Antibiotics: when they help and when they do nothing?
- See a doctor if symptoms last more than a few weeks, get worse quickly, stop you doing everyday things, or if you notice sudden pain, breathing trouble, fainting or bleeding.
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