A careful search of Embase, PsychINFO, Medline for studies estimating the prevalence rate of anticholinergic adverse effects identified only three surveys and each was flawed in substantial ways.

To estimate prevalence/incidence rates of anticholinergic effects of antipsychotic medications.

Inclusion criteria: Any systematic reviews involving people with schizophrenia-like illnesses, being treated with any antipsychotic medications and undertaken by the Cochrane Schizophrenia Group.

Outcome measures: Prevalence/incidence rate of any anticholinergic side effect.

Search strategy: Cochrane Library (www.intersience.willey.com) was searched in January 2007; all printed figures were inspected and data extracted. This process was repeated twice.

Analyses: Simple frequencies, proportions and confidence intervals.

46% of trials therein reported data on anticholinergic effects. However, there were also many relevant studies where anticholinergic effects were not reported. Blurred vision, dry mouth and constipation are common adverse effects of all antipsychotic drugs.

This is by far the largest study estimating the proportion of people on specific antipsychotic drugs who experience these problematic adverse effects. The newer generations of drugs do seem to have a spectrum of familiar and common anticholinergic effects. They are not clearly distinguishable from many of the older compounds.