ABSTRACT
Adverse effects of drugs on the gastrointestinal tract are common, although epidemiological data demonstrating overall frequency and impact are limited. Thus, lack of data arises because general estimates of frequency for wellestablished adverse effects are seldom established. Confident attribution is also difficult in the absence of data from control populations. Such difficulties are particularly obvious in examining the risks of functional symptoms such as diarrhoea, vomiting and constipation, because they are common in the general public. However, they also pose difficulty in assessment of disease burden related to most organic conditions, particularly when other causal factors are inadequately understood and possible interactions even less so.
