U.S. National Library of Medicine and NIH
Antibiotics are powerful medicines that fight bacterial infections. Used properly, antibiotics can save lives. They either kill bacteria or keep them from reproducing. Your body’s natural defenses can usually take it from there.
Antibiotics do not fight infections caused by viruses, such as
Colds Flu Most coughs and bronchitis Sore throats, unless caused by strep
If a virus is making you sick, taking antibiotics may do more harm than good. Each time you take antibiotics, you increase the chances that bacteria in your body will be able to resist them. Later, you could get or spread an infection that those antibiotics cannot cure.
When you take antibiotics, follow the directions carefully. It is important to finish your medicine even if you feel better. Do not save antibiotics for later or use someone else’s prescription.