Please note: This information was current at the time of publication but now may be out of date. This handout provides a general overview and may not apply to everyone. 

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Am Fam Physician. 2022;106(6):online

Related article: Antibiotic Use in Acute Upper Respiratory Tract Infections

What are antibiotics?

Antibiotics are medicines that can fight or prevent some infections. Infections are caused by two types of germs—bacteria and viruses.

When do I need antibiotics?

You need antibiotics to stop an infection caused by bacteria, such as strep throat and some sinus and ear infections.

Antibiotics do not work against infections caused by a virus. A virus causes most coughs, colds, sore throats, and sinus infections. When you have a virus, ask your doctor what you can do to feel better.

How do antibiotics work?

Antibiotics kill off the weaker germs the first few times you take them. At first you will start to feel better. However, the stronger germs are still alive. If you stop taking these medicines too soon (as soon as you start to feel better), the stronger germs can keep growing, and the antibiotic won’t work anymore.

What is antibiotic resistance?

Germs that can’t be killed by antibiotics can sometimes take over when the weaker germs are killed. This is called antibiotic resistance. It can happen when you take the same medicine over and over or when germs are left in your body after taking these medicines.

You may need to be treated with a stronger antibiotic if you have a resistant germ. Some kinds of resistant bacteria are so strong that no antibiotic will work.

How can I prevent antibiotic resistance?

Use antibiotics only when your doctor prescribes them. Don’t share these medicines with anyone else. Take your antibiotics exactly as your doctor tells you to.

Where can I get more information?

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