John: Hello, I'm John Hilton, editor of the Cochrane Editorial unit. Acute bronchitis is one of the commonest respiratory tract infections seen by general or family practitioners, with several reviews now available in the Cochrane Library and one of these, of the effects of antibiotics, was updated in June 2017. We asked the lead author, Susan Smith, a GP from Dublin, Ireland, based at the Department of General Practice in the RCSI Medical School, to tell us what they found.

Susan: People presenting to primary care with acute bronchitis will usually have an acute cough and a high temperature, and, although the benefits and potential harms of using antibiotics for this condition are unclear, they are often given them.
We did our review to try to resolve this uncertainty by bringing together the evidence on whether antibiotics improve clinical outcomes and to assess their adverse effects. We included randomized trials of any antibiotic therapy compared with placebo or no treatment in acute bronchitis or acute productive cough, in people who do not have an underlying lung disease.
We included 17 trials with a total of almost 5100 participants. 16 of these trials compared antibiotics to a placebo, and the quality of trials was generally good. On the positive side, participants given antibiotics were less likely to have cough or night cough at follow up and their illness cleared up quicker. However, on average, this amounted to a difference of only half a day, in the context of an illness that lasts on average 8-10 days. There were also significantly more adverse effects in the antibiotic patients, with the most commonly reported being nausea, vomiting, diarrhoea, headache and rash. 
Considering all this evidence together, we’ve concluded that there is limited evidence of clinical benefit in the use of antibiotics in acute bronchitis. They may have a modest beneficial effect in particular types of patient such as frail, elderly people who have other illnesses as well as the acute bronchitis, but relatively few of these have been included in studies to date. And, when deciding whether or not to use antibiotics for acute bronchitis, the size of any benefit needs to be considered carefully, given the potential side effects, the rise in antibiotic resistance from overuse and the cost of antibiotic treatment.

John: If you would like to read more about the available evidence on these different factors, just visit Cochrane Library dot com, where a simple search for 'antibiotics for bronchitis' will pick up Susan’s review.