Some knowledge of the epidemiology of poisoning (toxicoepidemiology), preferably from your area, is useful as an aid to diagnosis when the history of ingestion is unclear. Common poisonings occur commonly. The poisons ingested vary substantially between countries and between urban and rural areas (where pesticides and herbicides are more common). They are also different for adults, adolescents and children. Though the medications ingested must to some extent reflect what is prescribed in the community, patients are far more likely to ingest some types of drugs (per prescription) than others (Buckley et al 1995).

A combination of knowledge of the possible toxic effects of drugs, the frequency with which these effects occur and the frequency with which these drugs are taken in overdose leads to a much more sensible approach to diagnosis than one based solely on a list of drugs reported to have caused a particular complication (see differential diagnosis).

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