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Bacterial or viral?

Some illnesses can't be helped with antibiotics, because they're caused by a virus.

Antibiotics will not help you when you have the flu.

That's because the flu is caused by a virus—the influenza virus—and antibiotics fight bacteria, not viruses.

But what if a case of the flu turns into pneumonia? Would antibiotics be useful then?

That would depend on whether the pneumonia is being caused by a bacterial infection or a virus.

The decision about when and how to use antibiotics is complicated. That's one of the reasons you should take them only when a doctor prescribes them for you. Another reason is antibiotic resistance. Using antibiotics improperly can help create strains of "superbugs," bacteria that antibiotics can't treat.

Your doctor can tell you whether your illness will respond to antibiotics. The Centers for Disease Control and Prevention and the American Academy of Family Physicians offer the following general guidelines for when antibiotics might, or might not, help:

  • Ear infections: Some, but not all, ear infections need antibiotics.
  • Sore throat: Most sore throats are caused by viruses. Strep throat is a bacterial illness, but diagnosis requires lab analysis of a throat swab.
  • Colds and the flu: These are viral illnesses that won't respond to antibiotics.
  • Cough or bronchitis: These illnesses are almost always viral. However, if a cough or other lung problem persists, you should see your doctor.
  • Urinary tract infections: These usually require antibiotics.

If your doctor doesn't recommend antibiotics for an illness, don't pressure him or her to give you some just in case. And if your doctor does prescribe antibiotics, be sure to take all the medicine as prescribed. Taking antibiotics inconsistently can lead to resistant bacteria.

Reviewed 11/30/2022

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