What's the difference between a virus and a bacterial infection, and why don't antibiotics work on viruses?

The simplest way to think about the difference is to look at their structure and how they reproduce.

Bacteria are single-celled, living organisms. They can survive on their own in various environments, inside or outside the body. Most bacteria are actually harmless or even helpful, but some can cause infections by invading tissues and multiplying.

Viruses are much smaller and are not considered "living" in the same way. A virus is essentially a tiny genetic code encased in a protein shell. It cannot survive or reproduce on its own; it acts like a hijacker, entering a healthy cell and forcing that cell to produce more viruses until the host cell often dies.

Why antibiotics don’t work on viruses:

Antibiotics are specifically designed to target the biological processes that bacteria need to survive—such as building their cell walls or synthesizing their own proteins. Because viruses don't have these structures, they remain completely unaffected by antibiotics.

Using antibiotics against a virus is like trying to use a hammer to fix a software bug: the tool simply isn't designed to interact with the target.

Important note: Taking antibiotics when you have a viral infection not only fails to treat the virus, but it can also contribute to "antibiotic resistance," where bacteria evolve to become immune to the drugs we rely on to treat real bacterial infections. Always consult a healthcare professional to determine if an infection is viral or bacterial before seeking treatment.