There is no strong evidence that antihistamines are
effective in treating cough. Older generation antihistamines have
been suggested as having anti-cough effects. 86 Antitussives are
effective in the treatment of non-phlegm cough, but they are not as
effective when it comes to sputum cough.
Furthermore, studies have shown that antihistamines have no role in
treating colds, nor do they have the ability to reduce the duration of
symptoms. 85 However, antihistamines with sedative properties
have been shown to suppress coughing and cause drowsiness, so
they may be an appropriate treatment for nocturnal cough.