Sounds like 'oh-MEP-ra-zol'

Easy-to-read medicine information about omeprazole – what it is, how to take omeprazole safely and possible side effects.

Type of medicine

Also called

  • Belongs to a group of medicines known as proton pump inhibitors
  • Dr Reddy's Omeprazole®
  • Losec®
  • Omezol Relief®

 What is omeprazole?

  • Omeprazole reduces the amount of acid produced in your stomach.
  • It is used to treat a number of stomach-related conditions caused by too much acid, such as indigestion, reflux, and ulcers.
  • It can also prevent ulcers from forming, or help the healing process where damage has already occurred.
  • Omeprazole may be given (along with antibiotics) to get rid of Helicobacter pylori, a bacteria found in the stomach which can cause ulcers. Read more about Helicobacter pylori.
  • Omeprazole may be used to prevent ulcers caused by medicines such as non-steroidal anti-inflammatory drugs (NSAIDs). Examples of NSAIDs are diclofenac, ibuprofen, naproxen.


  • The usual dose of omeprazole is 20 mg a day.
  • For some people, 10 mg a day is enough; others need a higher dose of 40 mg a day.
  • The pharmacy label on your medicine will tell you how much omeprazole to take, how often to take it, and any special instructions. 
  • Duration (how long you need to take it) varies from one week to many years.
  • If you have been taking omeprazole for a year or more, ask your doctor if you could step down to an H2 blocker (such as ranitidine). Recent studies suggest there may be a number of risks from long-term use of proton pump inhibitors like omeprazole including an increased risk of heart attacks, bone fractures and nutrient deficiencies such as low magnesium. 

How to take omeprazole?

  • Take omeprazole at the same time each day, usually in the morning.
  • Omeprazole is usually taken once a day, but some people may need to take it twice a day. Your doctor will advise you on how often to take omeprazole.
  • Swallow the capsule whole with a glass of water. Do not crush or chew - it does not work properly if the capsule is crushed or chewed.
  • If you find it difficult to swallow the capsule, you may open the capsule and sprinkle the pellets over some fruit juice, or yoghurt and swallow without chewing.
  • Omeprazole can be taken before or after food, although taking it before food is best.
  • If you forget to take your dose, take it as soon as you remember that day.
  • But, if it is nearly time for your next dose, just take the next dose at the right time. Do not take double the amount.

Possible side effects

Like all medicines, omeprazole can cause unwanted side effects, although not everyone gets them. Often unwanted side effects improve as your body adjusts to the new medicine.

Side effects What should I do?
  • Stomach upset, feeling sick
  • Feeling bloated, gas in the tummy
  • Loose stool (mild diarrhoea)
  • Constipation
  • These are quite common when you first start taking omeprazole
  • Tell your doctor if troublesome 
  • Signs of low magnesium such as muscle cramps, weakness, tiredness, feeling irritable, and changes in heart beat
  • Increase your intake of magnesium-rich foods such as wholegrain cereals, green leafy vegetables (spinach, parsley, cabbage), peas, lean meats, nuts, seeds and bananas
  • Tell your doctor if troublesome — you may need a magnesium supplement
  • Severe diarrhoea (loose, watery, frequent stools)  
  • Omeprazole can increase the chance of getting severe diarrhoea (which may be caused by a bacteria called clostridium difficle)
  • Stop omeprazole and tell your doctor immediately 
  • Signs of an allergic reaction such as rash, fever, painful joints
  • Tell your doctor immediately or ring HealthLine 0800 611 116 
  • Worsening stomach problems such as really bad stomach pain, blood in the stool or black stools, vomit blood or dark coloured vomit
  • Tell your doctor immediately or ring HealthLine 0800 611 116 


Omeprazole may interact with a few medications and herbal supplements, so check with your doctor or pharmacist before starting omeprazole or before starting any new medicines.

Learn more

Medsafe Consumer Information Sheet:


Omezol Relief

New Zealand Formulary Patient Information: omeprazole

Credits: Created by Health Navigator NZ. May 2014. Reviewed By: Kate Lloyd August 2014. Latest update by Health Navigator 15 June 2015