• Omeprazole reduces the amount of acid produced in the stomach.
  • Some omeprazole capsule and tablets should be swallowed whole, others can be mixed with fruit juice or yoghurt to make swallowing easier - check the manufacturer's printed information leaflet from inside the pack for directions.
Type of medicine Proton pump inhibitor
Used for Gastric ulcers, duodenal ulcers, gastro-oesophageal reflux disease, acid-related dyspepsia, and Zollinger-Ellison syndrome
Eradication of Helicobacter pylori
To treat or prevent ulcers caused by non-steroidal anti-inflammatory drugs (NSAIDs)
To reduce gastric acid before surgery
Also called Losec®
Losec MUPS®
Axorid® (omeprazole in combination with the anti-inflammatory ketoprofen)
Available as Capsules, tablets, dispersible tablets and injection

Acid is produced naturally in your stomach to help you digest food and to kill bacteria. This acid is irritant so your body produces a natural mucus barrier which protects the lining of your stomach. In some people this barrier may have broken down allowing the acid to damage the stomach causing inflammation, ulcers and other conditions. In other people there may be a problem with the muscular band at the top of the stomach that keeps the stomach tightly closed. This may allow the acid to escape and irritate the oesophagus. This is called 'acid reflux' and can cause heartburn and/or oesophagitis.

Proton pump inhibitors such as omeprazole stop cells in the lining of the stomach from producing too much acid. This can help prevent ulcers from forming or assist the healing process. By decreasing the amount of acid, they can also help to reduce acid reflux related symptoms such as heartburn.

Omeprazole is also used to protect the stomach from irritation and ulceration caused by non-steroidal anti-inflammatory drugs (NSAIDs) such as ketoprofen. It can also be used as one part of a treatment to get rid of Helicobacter pylori, a bacterium found in the stomach which can cause ulcers.

Before taking omeprazole make sure your doctor, dentist or pharmacist knows:

  • If you are pregnant, trying for a baby or breast-feeding.
  • If you have liver problems.
  • If you have any of the following symptoms: bleeding, difficulty swallowing, being sick frequently, or unexplained weight loss.
  • If you have ever had an allergic reaction to this or any other medicine.
  • If you are taking any other medicines, including those available to buy without a prescription, herbal and complementary medicines.
  • Before starting this treatment, read the manufacturer's printed information leaflet from inside the pack.
  • Take omeprazole exactly as your doctor has told you.
  • Try to take omeprazole at the same time each day to avoid missing any doses. The usual dose is once a day in the morning. However, if you are taking omeprazole for Helicobacter pylori eradication, you will be asked to take two doses a day - one in the morning and one in the evening.
  • If you forget to take a dose, take it as soon as you remember unless it is nearly time for your next dose, in which case leave out the missed dose. Do not take two doses together to make up for a forgotten dose.
  • If you find capsules or tablets difficult to swallow, let your doctor know. Some omeprazole capsule and tablets can be mixed with fruit juice or yoghurt to make swallowing easier and your doctor can prescribe these for you.
  • Smoking increases the amount of acid produced by the stomach and will aggravate your condition. If you smoke, talk to your doctor or pharmacist about quitting.
  • Try to avoid foods and drinks that may upset your stomach such as alcohol, citrus fruits/juices, drinks containing caffeine, tomatoes and spicy food.
  • If you have bought omeprazole 'over the counter' from a pharmacy, do not take it for more than 4 weeks without speaking with your doctor.
  • Recent studies suggest that there may be a slight increase in the risk of bone fractures when proton pump inhibitors like omeprazole are taken for longer than a year. If this affects you, speak with your doctor to check that you are taking enough vitamin D and calcium to reduce this risk.
  • Try to keep your regular appointments with your doctor. This is so your progress can be monitored.
  • If you are having an operation or dental treatment, tell the person carrying out the treatment that you are taking omeprazole.
  • If you buy any medicines, check with a pharmacist that they are safe to take with omeprazole.

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. These usually improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following side-effects continue or become troublesome.

Common side-effects - these affect less than 1 in 10 people who take this medicine What can I do if I experience this
Feeling or being sick, stomach ache, flatulence Eat little and often. Stick to simple or bland foods
Diarrhoea Drink plenty of water to replace any lost fluids
Constipation Try to eat a well balanced diet containing plenty of fibre and drink 6-8 glasses of water each day
Headache Ask your pharmacist to recommend a suitable painkiller. If the headache continues speak with your doctor

If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist.

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.

  • Never take more than the prescribed dose. If you suspect that you or someone else has taken an overdose of this medicine go to the accident and emergency department of your local hospital at once. Take the container with you, even if it is empty.
  • This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
  • Never keep out of date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
  • If you have any questions about this medicine ask your pharmacist.

Further reading & references

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Helen Allen
Current Version:
Peer Reviewer:
Prof Cathy Jackson
Last Checked:
Document ID:
3249 (v26)
The Information Standard - certified member