Please note: This information was current at the time of publication. But medical information is always changing, and some information given here may be out of date. For regularly updated information on a variety of health topics, please visit, the AAFP patient education website.

Information from Your Family Doctor

Antibiotics: When They Can and Can’t Help


Am Fam Physician. 2006 Oct 1;74(7):1188.

What are antibiotics?

Antibiotics are strong medicines that can stop some infections and save lives. But antibiotics can cause more harm than good when they are not used the right way.

Do antibiotics always work?

Antibiotics only work against infections caused by bacteria. They do not work against infections caused by viruses. Viruses cause colds, the flu, and most coughs and sore throats.

What is bacterial resistance?

Antibiotics usually kill bacteria or stop them from growing. But some bacteria are resistant to certain antibiotics. This means that the antibiotics don’t work against them. Bacteria get resistant more quickly when antibiotics are used too often or are not used the right way.

What can I do to help myself?

Don’t expect antibiotics to cure every illness. Do not take antibiotics for viral illnesses like colds or the flu. The best thing you can do is let colds and the flu run their course. Sometimes this can take two weeks or more.

How do I know when I need antibiotics?

It depends on what is causing your infection. The following are some basic guidelines:

  • Colds and flu. Viruses cause these illnesses. They cannot be cured with antibiotics.

  • Cough or bronchitis. Viruses almost always cause these. If you have a problem with your lungs or an illness that lasts a long time, bacteria may be the cause. Your doctor may decide to try using an antibiotic.

  • Sore throat. Most sore throats are caused by viruses and cannot be treated with antibiotics. Strep throat is caused by bacteria and can be treated with antibiotics. Your doctor can do tests to see what is causing your sore throat.

  • Ear infections. Most ear infections in adults and older children will get better without antibiotics. Very young children and people with a high fever might need antibiotics.

  • Sinus infections. Antibiotics are sometimes used to treat sinus infections that are caused by bacteria. However, a runny nose and yellow or green mucus may be caused by a cold virus and do not always mean you need an antibiotic.

This handout is provided to you by your family doctor and the American Academy of Family Physicians. Other health-related information is available from the AAFP online at

This information provides a general overview and may not apply to everyone. Talk to your family doctor to find out if this information applies to you and to get more information on this subject.


Copyright © 2006 by the American Academy of Family Physicians.
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