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Q: I know that antibiotics don’t treat viruses, but at some point, isn’t it time to try one?

A: With the caveat that medical expertise is required to differentiate bacterial illnesses from viral ones, many common infections have features that can help you decide when an antibiotic might be appropriate.

In patients with bronchitis, the Centers for Disease Control and Prevention suggests that an antibiotic could be needed in patients who have a heart rate greater than 100 beats per minute or a fever greater than 100.4 degrees, or who are breathing more rapidly than 24 times per minute.

In patients with sinusitis, the American College of Physicians states that an antibiotic might be indicated when symptoms persist for more than 10 days; are severe; or are associated with three days of fever greater than 102.2 degrees, coloured nasal discharge and facial pain.

Antibiotics may also be needed in cases of “double sickening,” that is, worsening after several days of initial improvement.

In patients with sore throat, the Infectious Diseases Society of America recommends that antibiotics be used only in patients who have a positive strep test.

Symptoms that suggest a viral sore throat — and hence do not require an antibiotic — include cough, runny nose and hoarse voice.


The American Academy of Pediatrics advises that ear infections may require an antibiotic in children older than six months who have severe pain, or more than 48 hours of pain, or a fever greater than 102.2 degrees.

Most respiratory infections, including the common cold, however, should not be treated with an antibiotic. The sneezing, runny nose, sore throat, cough, low-grade fever and headache of the common cold will not respond to an antibiotic.

This is also true for most cases of sinusitis, for acute bronchitis (a chest cold), and for most sore throats.

Prescribing antibiotics for viral infections is inappropriate. Yet, many doctors do this. Doctors in the United States write more than 150 million antibiotic prescriptions a year, one-quarter to one-half of which are probably inappropriate.

Such prescriptions bring unnecessary costs, preventable side effects and drug-resistant bacteria. For this reason, it is important to reserve antibiotics for infections that require them.

The best way to ensure that an antibiotic is right for you is to engage your doctor in shared decision-making. A doctor who understands your concerns and who knows your medical history will be less likely to hurry you out the door with an inappropriate prescription.