INTRODUCTION: Since 2011, the Spanish Society of Family Medicine has recommended general practitioners (GPs) to ask their patients to stop taking antibiotics when they suspect a viral infection. However, this practice is seldom used because uncertainty about diagnosis, and fear of consequences of discontinuing antibiotic therapy, as well as perceived pressure to continue prescribing antibiotics and potential conflict with patients are more of a concern for GPs than antibiotic resistance. The main objective of this study is to determine whether discontinuation of antibiotic therapy when a GP no longer considers it necessary has any impact on the number of days with severe symptoms. METHODS AND ANALYSIS: This is a multicentre, open-label, randomised controlled clinical trial. The study was conducted in 10 primary care centres in Spain. We included patients from 18 to 75 years of age with uncomplicated acute respiratory tract infections-acute rhinosinusitis, acute sore throat, influenza or acute bronchitis-who had previously taken any dose of antibiotic for <3 days, which physicians no longer considered necessary. The patients were randomly assigned to the usual strategy of continuing antibiotic treatment or to discontinuing antibiotic therapy. A sample size of 240 patients per group was calculated on the basis of a reduction of 1 day in the duration of severe symptoms being a clinically relevant outcome. The primary outcome was the duration of severe symptoms, that is, symptoms scored 5 or 6 by means of validated symptom diaries. Secondary outcomes included antibiotics taken, adverse events, patient satisfaction and complications within the first 3 months. ETHICS AND DISSEMINATION: The study was approved by the Ethical Board of Fundació Jordi Gol i Gurina (reference number: 16/093). The findings of this trial will bedisseminated through research conferences and peer-reviewed journals.