Antibiotics

Health, disease and the development of medicines · Antibiotics, culturing microorganisms and new medicines · note 1 of 2

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AntibioticsSpec 5.16

In short

Antibiotics are medicines that treat bacterial infections by inhibiting cell processes in the bacterium, without harming the host's own cells. They cannot treat viral diseases such as HIV, colds or flu, because viruses are not cells. Viruses live and reproduce inside host cells, so they do not have the cell processes that antibiotics inhibit.

Antibiotics are medicines that treat bacterial infections. They work by inhibiting cell processes in the bacterium. They do not harm the host organism's own cells, because the host's cells work differently.

Antibiotics can only be used to treat bacterial infections. Viruses are not cells. They live and reproduce inside host cells, so the cell processes that antibiotics inhibit are not present in a virus. Antibiotics therefore do not work on viral diseases such as HIV or Ebola.

Common mistake:

Antibiotics do not 'kill viruses', and they cannot treat a cold or flu. State that they act on processes in bacterial cells but not host cells.

Written and checked against the Edexcel GCSE Combined Science (1SC0) specification · Updated October 2026

Frequently asked questions

Why can't antibiotics kill viruses?

Antibiotics cannot kill viruses because they work by inhibiting cell processes in bacteria, and viruses are not cells. Viruses live and reproduce inside host cells, so they do not have the cell processes that antibiotics target. This is why antibiotics cannot be used to treat viral diseases such as HIV, colds or flu.

What are the stages of developing a new medicine?

New medicines go through four stages: discovery of a chemical that might treat the disease, development to improve it, preclinical testing on cells, tissues and live animals to check toxicity and effectiveness, and clinical testing on people. Clinical testing starts with a few healthy volunteers to check safety, then patients to find the dose.