Antibiotics are powerful drugs used to treat certain illnesses. But they do not cure everything, and unnecessarily taking antibiotics can even be harmful. Viruses cause colds and flu. Antibiotics can’t kill viruses. Antibiotics do kill specific bacteria that can cause things such as urinary tract infections and strep throat. Your doctor will tell you whether an antibiotic is advised for your particular illness.
Taking an antibiotic when it isn’t needed can increase your chances of developing antibiotic resistance, so that in the future certain bacteria may not respond to antibiotics and may continue to cause infection. If you are prescribed an antibiotic, take it exactly as directed.
— Source: Monroe Carell Jr. Children’s Hospital at Vanderbilt University, Nashville, TN