Background: Although antihistamines are prescribed in large quantities for the common cold, there is little evidence to whether these drugs are effective.
Objectives: To assess in patients with a common cold the effects of antihistamines in alleviating nasal symptoms, or in shortening of illness duration.
Search strategy: We searched the Cochrane Acute Respiratory Infections Group Specialized Register and EMBASE up to December 2002; Cochrane Central Register of Controlled Trials (CENTRAL) and MEDLINE up to February 2003. We also followed up references in identified papers. We appealed for further articles at a major international conference on Acute Respiratory Infections (1997). We corresponded with experts and got in touch with pharmaceutical companies.
Selection criteria: Randomised, placebo-controlled trials on treatment of common cold with antihistamines, used either singly or in combination, in adults or children.
Data collection and analysis: Data were extracted by two reviewers and authors were contacted for further data. Trials were subdivided into monotherapy and combination therapy. Data on general recovery, nasal obstruction, rhinorrhea, sneezing, and side-effects were extracted and summarized in a systematic review.
Main results: We included thirty two papers describing 35 comparisons; 22 trials studied monotherapy, 13 trials a combination of antihistamines with other medication. A total of 8930 people suffering from the common cold were included. There were large differences in study designs, participants, interventions, and outcomes. There was no evidence of any clinically significant effect - in children or in adults - on general recovery of antihistamines in monotherapy. First generation - but not non-sedating - antihistamines have a small effect on rhinorrhea and sneezing. In trials with first generation antihistamines the incidence of side effects (especially sedation) is significantly higher with active treatment. Two trials, studying a combination of antihistamines with decongestives in small children, both failed to show any effect. Of the eleven trials on older children and adults, the majority show an effect on general recovery and on nasal symptom severity.
Reviewer's conclusions: Antihistamines in monotherapy - in children as well as in adults - do not alleviate to a clinical extend nasal congestion, rhinorrhoea and sneezing, or subjective improvement of the common cold. First generation antihistamines also cause more side-effects than placebo, in particular they increase sedation in cold sufferers. Combinations of antihistamines with decongestives are not effective in small children. In older children and adults most trials show a beneficial effect on general recovery as well as on nasal symptoms. It is however not clear whether these effects are clinically significant.