What should you know about empiric antibiotics?

A clinician weighs the affected body area, examination findings, severity, recent medicines, allergies and local clinical practice. The initial choice may be changed if a sample, examination or treatment response suggests another approach. Antibiotics treat bacteria, not viruses, so a cough from acute bronchitis may not need them. Taking an unsuitable antibiotic can cause side effects and make future infections harder to treat.

Take the medicine exactly as prescribed and check what to do if you miss a dose. Tell the prescriber about allergies, pregnancy, kidney problems and other medicines. Do not share leftover tablets or save them for a later illness. Report troublesome diarrhoea, a spreading rash or other unexpected reactions; swelling of the face or difficulty breathing needs emergency help. Follow-up may be needed for infections such as cellulitis, chlamydia or gonorrhoea.

Seek review if symptoms worsen, fail to improve as expected, or return after treatment. Get urgent help for confusion, collapse, severe weakness, breathing difficulty, rapidly spreading redness or severe allergic symptoms. The urgency depends on the illness and your condition, not simply on whether an antibiotic has been prescribed.

What infection are we treating, and what evidence supports an antibiotic? Should a sample be tested? How will we know whether the medicine needs changing?