Acute bronchitis is a clinical diagnosis for an acute cough, which may or may not be productive of mucus or sputum. It occurs when the tubes (bronchi) within the lungs become inflamed and may be caused by viruses or bacteria. Symptoms generally last for two weeks but the associated cough can last for up to eight weeks. Recently, there has been controversy over the term acute bronchitis as it covers a range of clinical presentations that may overlap with other diagnoses such as upper or lower respiratory tract infections. For this reason, some have suggested using the term 'acute lower respiratory tract infection when pneumonia is not suspected' as this is more specific. Antibiotics are commonly prescribed to treat this condition though other treatments providing symptom relief are commonly used. Antibiotics can have adverse effects such as nausea and diarrhea but can cause more serious reactions related to anaphylaxis in those allergic to them. In healthy communities, there is little evidence of bacterial infection in people with bronchitis and there is no practical test to distinguish between bacterial and viral bronchitis. Within this context the use of antibiotics to treat acute bronchitis is controversial but common. Concerns that prescribing unnecessary antibiotics increases antibiotic resistance exists.
We included 17 trials with 3936 participants diagnosed with acute bronchitis and randomly assigned to receive any antibiotic treatment or a placebo or no treatment. Co-treatments with other medications to relieve symptoms were allowed if they were given to all patients. We excluded patients with pre-existing underlying pulmonary disease such as chronic bronchitis or chronic obstructive pulmonary disease. The quality of trials was generally good, particularly for more recent studies. There was limited evidence to support the use of antibiotics for acute bronchitis and a large study involving 1038 patients from 12 countries included in this update has confirmed this finding. Some people treated with antibiotics recovered a bit more quickly with reductions in cough-related outcomes though the difference was of doubtful clinical significance as it amounted to a difference of half a day over an 8 to 10 day period. There was a statistically significant but small increase in adverse side effects in patients treated with antibiotics. The most commonly reported side effects included nausea, vomiting or diarrhea, headaches, skin rash and vaginitis.The available evidence suggests that there is no benefit in using antibiotics for acute bronchitis in otherwise healthy individuals though more research is needed on the effect in frail, elderly people with multimorbidities who may not have been included in the existing trials. The use of antibiotics needs to be considered in the context of the potential side effects, medicalisation for a self-limiting condition and costs of antibiotic use, particularly the potential harms at population level associated with increasing antibiotic resistance.