How effective are antihistamines for treatment of the common cold?
Antihistamines are of minimal to no benefit as mono-therapy for the common cold, and first-generation antihistamines may increase sedation in patients with a cold. Antihistamine-decongestant combinations reduce nasal symptoms and improve the recovery rate in older children and adults, but these combinations are not effective in younger children.
Although antihistamines are widely used in the treatment of the common cold, particularly as part of decongestant-antihistamine combinations, there is little evidence of benefit. De Sutter and colleagues reviewed 22 randomized, controlled trials (RCTs) of antihistamines as mono-therapy and 13 RCTs of antihistamines combined with another medication, usually a decongestant. Most studies excluded patients with allergic rhinitis.
There was some evidence of a small beneficial effect of first-generation antihistamines as monotherapy for rhinorrhea and sneezing and a small short-term benefit in terms of overall recovery (number needed to treat, 14). However, more patients taking a first-generation antihistamine experienced sedation (7.9 versus 4.4 percent; absolute risk increase, 3.5 percent; number needed to harm, 29). No studies found a benefit for second-generation, nonsedating antihistamines.
Antihistamine-decongestant combinations were not effective in younger children but did improve general recovery and nasal symptoms in older children and adults. However, the latter studies did not report the magnitude of benefit, so it was difficult to tell if the benefit was clinically and not just statistically significant. Of course, the benefit may have been largely due to the decongestant alone.