A number of issues affect the quality of the
reviews covered in this paper. These include a wide
range of design quality in the studies reviewed. The
dose and quality of some of the medicinal components
and combination medications are also issues
of concern. The latter two of these apply particularly
to OTC medications. Issues are also raised by
different methods of measuring end points, such as
continuous scales compared with dichotomous outcomes
(i.e. feeling well or absence of cough). As
some of the medications are designed for specific
purposes (e.g. cough suppressant), then absence of
cough will be appropriate. For decongestants, it
will be nasal discharge and stuffiness. This raises
the question of what would be the appropriate
outcome for an antihistamine for the common cold.