Omeprazole and excessive sweating, if unrecognised, may lead to unnecessary investigations.

The common side-eVects of omeprazole and other proton pump inhibitors (PPIs) are well known (ie, headache, nausea, diarrhoea, and skin rash), but there are others, which are uncommon and therefore less widely known and which may be specifically related to one member of the group. They may not be serious, but being very non-specific and relatively unknown, may tempt a clinician to look for a cause other than the prescribed drug. Omeprazole-induced hyperhydrosis is probably the most important example in this category. In general, PPIs are well tolerated, and treatment of patients with ZollingerEllison syndrome with omeprazole in doses of 60 to 360 mg a day for up to 6 years has not caused any serious side-eVects. 2 However, there have been occasional reports of serious idiosyncratic adverse reactions including hepatitis and renal failure with omeprazole.