Side effects reported with omeprazole in clinical studies have included nausea, diarrhoea, constipation, flatulence, abdominal colic, paresthesia, dizziness and headache but are rare. Skin rashes, leucopenia and transient elevation of plasma activation of hepatic aminotransferases have been observed occasionally in few patients and there has been no consistent relationship with treatment. Clostridium difficile-associated diarrhea [CDAD]; fractures.