Risk of agranulocytosis with metamizole in comparison with alternative medications based on health records in Spain.

Agranulocytosis was very rare but more common (above 4 times more) with metamizole than other analgesics. The impact of the drug-induced agranulocytosis was less precise with metamizole than the comparators due to its lower use, which precluded to find statistical differences in main analysis. The increased risk of hospitalized neutropenias with metamizole supports the link with its severity although triggers unavailable during the follow-up (ex. cytotoxic medication) can not be discarded.