Sorry, nothing in cart.
Blog
Omeprazole is a proton pump inhibitor that reduces stomach acid. It is used for heartburn, reflux and stomach ulcers, and with antibiotics for H. pylori infection.
What are the common side effects?
Headache, stomach pain, nausea or vomiting, constipation or diarrhoea, and wind can occur. Speak to a pharmacist or doctor if they bother you or do not go away.
Is long-term use a concern?
Serious side effects are more likely with a year or more of use. These include low vitamin B12 and weakened bones. Use it for as long as your doctor or the label directs.
Who should check first?
Check with a doctor or pharmacist if you have kidney or liver problems or osteoporosis, are pregnant or breastfeeding, or have had a reaction to a similar medicine. It can also affect some medical tests.
Can it interact with other medicines?
Yes, including digoxin, warfarin, clopidogrel, diazepam, phenytoin, St John’s wort and some HIV medicines.
When should I see a doctor?
See a doctor if symptoms get worse or do not improve, as omeprazole can hide symptoms of serious conditions, including stomach cancer. Seek advice for tiredness with muscle twitches or weakness, or a rash on sun-exposed skin with joint pain. Get emergency help for swelling of the throat or tongue, or trouble breathing.
Doses and formulations vary. Follow your prescriber, pharmacist and the leaflet supplied with your exact medicine. In Australia, call 000 for a medical emergency or the Poisons Information Centre on 13 11 26 for suspected poisoning or overdose. Outside Australia, use your local emergency and poison-information services.
Source: NHS: Omeprazole. General education does not replace individual medical advice. Updated November 2026.
Read more in our Health Guides. For website or catalogue questions, contact support; urgent medical concerns need a healthcare service.