# Antibiotic

A medicine that kills bacteria or stops them growing. It does not work against viruses.

Biology (school) · Part 04: Health and disease · Card 8 of 10 · Last updated 2026-10-19

## Analogy

A weedkiller that harms weeds but not the flowers.

## In practice

Penicillin treats bacterial infections such as strep throat.

## Practice

### Flashcards

- **Why do antibiotics not cure colds?** Colds are caused by viruses, and antibiotics only work on bacteria.

### Interview questions

**Explain why antibiotic resistance is a problem and how it can be reduced.**

- Mutations make some bacteria resistant
- Antibiotics kill non-resistant bacteria so resistant ones multiply
- Infections become harder to treat
- Doctors should prescribe antibiotics only when needed and patients should finish courses

## Questions people ask

### How do antibiotics work?

Different antibiotics attack bacteria in different ways. Penicillin, for example, stops bacteria building their cell walls, so they burst. Antibiotics are chosen to harm bacterial cells while leaving human cells alone. Doctors pick a specific antibiotic to match the kind of bacteria causing the infection.

### Why must you finish a course of antibiotics?

Stopping early may leave some bacteria alive, especially the toughest ones. These can multiply again and may be more resistant. Finishing the course is meant to remove all the bacteria. Doctors set the length of treatment carefully, and some now say it can be shortened.

## Related concepts

- [Antibiotic resistance](https://studyvisually.com/learn/science/biology-school/biology-school-part-4/biology-school-part-4-concept-9)

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