(HealthDay News) -- Preventing or treating bacterial infections are what antibiotics were designed to do.

But colds and flu, most coughs and bronchitis, and the majority of runny noses are triggered by viruses, and antibiotics won't prevent these maladies or make you feel better, the U.S. Centers for Disease Control and Prevention warns.

Unnecessary overuse of antibiotics allows bacteria to mutate and develop a resistance to these drugs, the CDC says. The agency offers these suggestions to help prevent development of resistant bacteria:

• Take your antibiotics exactly the way your doctor prescribed them. The same advice goes for your children.
• Don't ever stop antibiotics just because you begin to feel better. Always finish the entire prescription.
• Don't insist on an antibiotic to treat the flu or cold, bronchitis or a cough, a runny nose or a sore throat that isn't strep.