
06/27/2025
What are antibiotics?
Antibiotics are medicines that fight bacterial infections in people and animals. They work by killing the bacteria or by making it hard for the bacteria to grow and multiply.
Antibiotics can be taken in different ways:
Orally (by mouth). This could be pills, capsules, or liquids.
Topically. This might be a cream, spray, or ointment that you put on your skin. It could also be eye ointment, eye drops, or ear drops.
Through an injection or intravenously (IV). This is usually for more serious infections.
What do antibiotics treat?
Antibiotics only treat certain bacterial infections, such as strep throat, urinary tract infections, and E. coli.
You may not need to take antibiotics for some bacterial infections. For example, you might not need them for many sinus infections or some ear infections. Taking antibiotics when they're not needed won't help you, and they can have side effects. Your health care provider can decide the best treatment for you when you're sick. Don't ask your provider to prescribe an antibiotic for you.
Do antibiotics treat viral infections?
Antibiotics do not work on viral infections. For example, you shouldn't take antibiotics for:
Colds and runny noses, even if the mucus is thick, yellow, or green
Most sore throats (except strep throat)
Flu
Most cases of bronchitis
Used properly, antibiotics can save lives by fighting bacterial infections. Read about how to use antibiotics and about when not to use antibiotics.