What Is Antibiotics?

Used properly, antibiotics can save lives by fighting bacterial infections. Read about how to use antibiotics and about when not to use antibiotics.

*Health information sourced from the Centers for Disease Control and Prevention (CDC) and MedlinePlus, a service of the U.S. National Library of Medicine. co-pay.com is not affiliated with or endorsed by the U.S. government.

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

What are the side effects of antibiotics?

The side effects of antibiotics range from minor to very severe. Some of the common side effects include:

More serious side effects can include:

C. diff infections, which cause diarrhea that can lead to severe colon damage and sometimes even death
Severe and life-threatening allergic reactions
Antibiotic resistance infections

Call your health care provider if you develop any side effects while taking your antibiotic.

Why is it important to take antibiotics only when they're needed?

You should only take antibiotics when they are needed because they can cause side effects and can contribute to Antibiotic resistance infections. Antibiotic resistance happens when the bacteria change and become able to resist the effects of an antibiotic. This means that the bacteria continue to grow.

How do I use antibiotics correctly?

When you take antibiotics, it is important that you take them responsibly:

Always follow the directions carefully. Finish your medicine even if you feel better. If you stop taking them too soon, some bacteria may survive and re-infect you.
Don't save your antibiotics for later.
Don't share your antibiotic with others.
Don't take antibiotics prescribed for someone else. This may delay the best treatment for you, make you even sicker, or cause side effects.

Centers for Disease Control and Prevention