Omeprazole - Brand names: Losec, Losec MUPS, Pyrocalm

What omeprazole is for

Omeprazole is a medicine called a proton pump inhibitor (PPI). It reduces the amount of acid in your stomach.

It's used to treat or prevent conditions and symptoms such as:

• stomach ulcers
• heartburn
• gastro-oesophageal reflux disease (GORD)
• the stomach infection Helicobacter pylori (along with antibiotics)
• discomfort from severe reflux in children

How to take omeprazole

Omeprazole usually comes as tablets, capsules and liquid that you swallow. Some tablets can be dissolved in water.

How much to take and for how long depends on the type of omeprazole you're taking and why you're taking it.

It's usually taken once or twice a day. Some people may only need to take it for a few days, others may need to take it for several weeks, months or years.

Always check the packet or leaflet that comes with your medicine. Ask a pharmacist or doctor for advice if you're not sure how to take it or you have any problems taking it.

When taking omeprazole:

• try to take it at the same time each morning if you take it once a day, or at the same time each morning and evening if you take it twice a day
• you can take it with or without food
• swallow tablets and capsules with water – do not chew or crush capsules or tablets labelled "enteric coated" or "gastro resistant"

Ask a pharmacist for advice if you have problems swallowing pills or capsules. They may be able to suggest different ways to take your medicine.

If you miss a dose of omeprazole

If you forget to take a dose of omeprazole, take it as soon as you remember, unless it's nearly time for your next dose.

If it's nearly time for your next dose, skip the dose you missed and take your next dose at the usual time.

Do not take 2 doses at the same time to make up for a missed one.

If you take too much omeprazole

Taking an extra dose of omeprazole is unlikely to cause problems, but it's important to get medical advice if you take too much because it can sometimes be dangerous.

Advice about giving medicines to children

• How to give different types of medicines (Medicines for Children website)

Side effects of omeprazole

Like all medicines, omeprazole can cause side effects, but not everyone gets them.

Common side effects

Common side effects of omeprazole include:

• a headache
• stomach pain
• feeling sick (nausea) or being sick (vomiting)
• constipation or diarrhoea
• farting more than usual

Omeprazole will not usually affect your ability to drive, ride a bike or use machinery. But if you feel dizzy or have problems with your vision after taking it, wait until you no longer have these side effects.

Serious side effects

Omeprazole can sometimes cause serious side effects, but most of them are rare.

Possible serious side effects of omeprazole include:

• having a very low level of vitamin B12, which can cause symptoms such as tiredness, dizziness, or muscle twitches or weakness
• weakened bones, which can break more easily if you have a fall or injury
• an allergic reaction (anaphylaxis), which can cause symptoms such as a swollen throat or tongue, a raised, itchy rash or difficulty breathing
• a type of lupus that can cause rashes (particularly on parts of the body exposed to the sun) and joint pain

The chance of getting serious side effects can be higher if you take omeprazole for a long time (a year or more).

Who can and cannot take omeprazole

Most adults and children can take omeprazole. But the tablets you can buy from pharmacies and shops without a prescription are only for adults over 18 years old.

Omeprazole is not suitable for some people. For example, it may not be suitable if:

• you've had an allergic reaction or serious side effect from omeprazole or another proton pump inhibitor (PPI) medicine that reduces stomach acid
• you have a kidney or liver condition
• you have osteoporosis (weakened bones)

Before taking omeprazole, tell your doctor or a pharmacist if you have any medical conditions.

Omeprazole can also affect the result of some tests, including blood tests, checks for some types of tumours and a test to check inside your food pipe (oesophagus) and stomach (gastroscopy).

If you're referred for a test, you may need to stop taking omeprazole for a few days or weeks before you have the test. Check with the staff at the hospital or clinic where the test is being done.

Breastfeeding and omeprazole

You can usually take omeprazole while breastfeeding, but check with a pharmacist or doctor first.

It's rare for breastfed babies to get any side effects from medicine you're taking, but speak to a healthcare professional if you have any concerns about your baby.

Pregnancy and omeprazole

You can usually take omeprazole if you're pregnant, but check with a pharmacist or doctor first.

Find out more about taking proton pump inhibitors, including omeprazole, during pregnancy on the Bumps (Best Use of Medicines in Pregnancy) website

Taking omeprazole with other medicines, herbal remedies and supplements

There are some medicines, remedies and supplements that may not mix well with omeprazole.

These include:

• other medicines that reduce stomach acid, such as lansoprazole and famotidine
• the heart medicine digoxin
• some medicines to prevent blood clots, such as warfarin and clopidogrel
• the sedative diazepam
• the anti-seizure medicine phenytoin
• the herbal remedy for low mood, St John's Wort
• HIV medicines called nelfinavir and atazanavir

Before you take omeprazole, tell your doctor or a pharmacist if you're talking any other medicines, herbal remedies, vitamins or supplements.

If you bought omeprazole without a prescription, check the packet or leaflet that comes with the medicine to see if it's suitable for you. Speak to a pharmacist or doctor if you're not sure if you can take it.

Food and alcohol with omeprazole

You can eat as normal while taking omeprazole, but it's best to not drink alcohol because it can increase the amount of acid in your stomach and make your symptoms worse.