Antibiotics are common prescribed against influenza, although no trials of their efficacy have been published. We compared clinical and societal outcomes in 701 patients (56% flu-positive) according to use of antibiotics. The median duration of illness, rate of secondary visits, and lost workdays did not differ between antibiotic and non-antibiotic treated patients. Antibiotics are unnecessary expenses in the initial treatment of influenza, as they can give potential side-effects and contribute to spread of antibiotic-resistant bacteria.