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Am Fam Physician. 2006;74(6):969

See related article on antibiotics.

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, pneumonia (say: new-MOAN-yuh), and some sinus and ear infections.

Antibiotics do not work against infections caused by a virus. Most coughs, colds, and sore throats are caused by a virus. 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. If you do this, soon the antibiotic won’t work anymore.

What is antibiotic resistance?

Germs that can’t be killed by antibiotics can sometimes take over when all of 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 you have been 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?

Your doctor

Alliance Working for Antibiotic Resistance Education

Centers for Disease Control and Prevention

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