Antihistamines are widely used in
common cold medications, although the role of
histamine in the development of
common cold symptoms is unclear and the use of
antihistamines for the treatment of
common cold is controversial. It is clear that
antihistamines do not offer a cure for
common cold but they may alleviate symptoms of
sneezing and
runny nose. The present study was designed to investigate the efficacy of an
antihistamine,
doxylamine, on the symptoms of
runny nose and
sneezing associated with
common cold. We conducted a randomized double-blind study in cold sufferers. One thousand and one volunteers with cold symptoms were screened in four centres (UK, Denmark, Belgium, Germany) and 688 satisfied the entry criteria of the study. The main reasons for excluding subjects were a low nasal secretion weight (secretion weight < 0.2g, 72%) and a low subjective rhinorrhoea score (24%). Volunteers were randomized to receive either
doxylamine succinate 7.5 mg by mouth four times a day up to nine doses (n = 345) or placebo (n = 343). The principal measurements were prospectively defined as
runny nose and
sneezing symptom scores. Data were analysed on an intention-to-treat basis, using Cochran-Mantel-Haenszel statistics controlling for baseline symptom scores. A between-group comparison showed that
doxylamine-treated volunteers benefited from a significantly greater reduction in
runny nose scores (P < 0.01) and
sneezing scores (P < 0.001), than those volunteers in the placebo group.
Doxylamine therapy was well tolerated; the incidence of unexpected side-effects was comparable with placebo. Of the expected side-effects, 13.3% of
doxylamine-treated patients reported drowsiness. The incidence of
sedative effects was lower than has been reported for other commonly used first-generation
antihistamines.