Why don’t antibiotics work on colds?

Colds are caused by viruses, not bacteria. Over 200 different species of virus causing the common cold have been identified.

Antibiotics do not work at all in treating the common cold. A net designed to trap a human could let a tiny mouse escape. Antibiotics are medicines that kill bacteria, not viruses. Many antibiotics work by disrupting the bacteria's cell wall. Viruses don't even have a cell wall.

Antibiotics can actually make colds worse. By indiscriminately killing the beneficial bacteria, an environment more hospitable to the cold viruses is created.