Omeprazole

Omeprazole reduces the amount of acid your stomach makes. It is one of the most common treatments for heartburn, acid reflux and stomach ulcers.

Type of medicine

Proton pump inhibitor (PPI)

Also known as

Losec

Comes as

capsules, tablets, liquid, injection

How you get it

Some forms from a pharmacy without a prescription

What it is used for

Heartburn and acid reflux (GORD)
Healing and preventing stomach and duodenal ulcers
Getting rid of H. pylori infection, with antibiotics
Protecting the stomach in people taking anti-inflammatory painkillers
Zollinger-Ellison syndrome

Read our guides:

Acid reflux (GORD)

Off-label uses

Doctors sometimes prescribe a medicine for a condition it is not officially licensed for. This is called off-label use. It is legal and common when there is good evidence it helps, and your doctor should explain why they are suggesting it.

Omeprazole is not commonly used off-label.

How it works

Omeprazole blocks proton pumps in the stomach lining that release acid. Less acid means less irritation and allows ulcers and inflammation to heal.

Side effects

Like all medicines, Omeprazole can cause side effects, although not everyone gets them. Many are mild and ease after the first few weeks.

Common side effects

headache
stomach pain
diarrhoea or constipation
wind
feeling sick

Tell your doctor or pharmacist if these bother you or do not go away.

Serious side effects

These are rare. Call 111 or contact your doctor straight away if you get:

severe or watery diarrhoea that does not stop
muscle cramps or an irregular heartbeat after long use, which can be signs of low magnesium
a rash on sun-exposed skin with joint pain

Call 999 if you have signs of a serious allergic reaction, such as swelling of your lips, mouth, throat or tongue, or trouble breathing.

You can report any side effect to the Yellow Card scheme, run by the medicines regulator.

Stopping and withdrawal

Important safety information

See a GP if you need it for more than 2 weeks, have trouble swallowing, are losing weight or vomiting.
It can make clopidogrel work less well.
Long-term use can lower vitamin B12 and magnesium levels.

Questions about your medicine?

A pharmacist can answer questions about your medicines for free, without an appointment. You can also ask your GP for a medication review. Check if you can get free prescriptions.