toxicity and drug interactions

Last reviewed 01/2022

Omeprazole has an incidence of adverse events of about 1%; this is about the same as cimetidine and ranitidine. Adverse events of omeprazole reported to the CSM include incidences of:

• headache
• rash
• diarrhoea, constipation and flatulence
• dizziness
• somnolence and insomnia
• malaise
• paraesthesia

Omeprazole inhibits one of the metabolic pathways of warfarin and phenytoin and thus monitoring of INR is justified when omeprazole is introduced in patients already taking either or the latter drugs.