Please note: This information was current at the time of publication but now may be out of date.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. For regularly updated information on a variety of health topics, please visit familydoctor.org, the AAFP patient education website.

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Am Fam Physician. 2000;62(12):2693

What are antibiotics?

Antibiotics are strong medicines that can stop some infections and save lives. When they aren't used the right way, antibiotics can cause more harm than good. You can protect yourself and your family by knowing when you should use antibiotics and when you should avoid them.

Will antibiotics work against my cold or the flu?

No. Antibiotics only work against infections caused by bacteria. They don't work at all against infections caused by viruses. Viruses cause the flu, colds, and most coughs and sore throats.

What is “bacterial resistance”?

Usually antibiotics kill bacteria or stop them from growing, but some bacteria have grown so strong that antibiotics don't work against them. These stronger bacteria are called “resistant” because they resist antibiotics. Resistant bacteria develop when antibiotics are used too often or are not used correctly.

Resistant bacteria sometimes can be treated with more powerful medicines. These medicines may have to be given intravenously (through a vein) in a hospital. A few kinds of resistant bacteria are untreatable.

What can I do to help myself and my family?

Don't expect antibiotics to cure every illness. Don't take antibiotics for colds or flu. Often, the best thing you can do is to let colds and flu run their course. Sometimes this can take two weeks or more. Call your doctor if your illness gets worse after two weeks.

How do I know when I need antibiotics?

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

  • Colds and flu—These illnesses are caused by viruses. They can't be cured with antibiotics.

  • Cough or bronchitis—These are almost always caused by viruses. However, if you have a lung condition or the illness lasts a long time, your infection may actually be caused by bacteria. Your doctor may decide to try treatment with an antibiotic.

  • Sore throat—Most sore throats are caused by viruses and don't require antibiotics, but strep throat is caused by bacteria and requires treatment with antibiotics. A throat swab and a lab test are needed before your doctor will prescribe an antibiotic for a sore throat.

  • Ear infections—There are several types of ear infections. Antibiotics are used for most, but not all, ear infections.

  • Sinus infections—Even if you have a runny nose, or yellow or green mucus in your nose, you may not need an antibiotic. Antibiotics should only be used for severe infections or infections that last more than two weeks because these infections may be caused by bacteria.

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