Our knowledge relating to
adverse drug reactions (ADRs) of phytomedicines is highly fragmentary. The aim of this study was to define the prevalence of ADRs following medication with herbal or synthetic
expectorants. In a multicentre, comparative post-marketing surveillance study of more than 3000 patients with acute
bronchitis, about half were treated with a herbal remedy (SinupretR) and the other half with various other
expectorants. In ascending order of incidence, ADRs were noted during mono-medication of SinupretR (0.8%),
Ambroxol (1.0%) and
acetylcysteine (4.3%). When concomitant drugs were used, this rank order was unchanged but incidence rates were markedly increased (3.4, 6.5 and 8.2%, respectively). The most frequent ADRs were gastrointestinal symptoms. It is concluded that
expectorants are associated with ADRs in roughly 1-5% of cases undergoing single
drug treatment and in 3-10% when more than one medication is being used. Amongst the
expectorants used in this study, the
herbal preparation SinupretR is associated with the lowest incidence of ADRs.