Omeprazole is a type of medicine called a proton pump inhibitor (PPI). Proton pumps are enzymes in the lining of your stomach that help it make acid to digest food. Omeprazole prevents proton pumps working properly which reduces the amount of acid the stomach makes.
Sometimes, omeprazole is taken for a rare condition caused by a tumour in the pancreas or gut called Zollinger-Ellison syndrome.
Omeprazole comes as capsules, tablets and as a liquid that you swallow.
All types of omeprazole are available on prescription. You can buy 20mg tablets from pharmacies and supermarkets.
Who can take omeprazole
Omeprazole can be taken by most adults. It can also be taken by children and babies if it's been prescribed by a doctor.
To make sure omeprazole is safe for you, tell your doctor if you:
- have ever had an allergic reaction to omeprazole or any other medicine
- have liver problems
- are due to have an endoscopy
Ask your doctor if you should stop taking omeprazole a few weeks before your endoscopy. This is because omeprazole may hide some of the problems that would usually be spotted during an endoscopy.
Always follow instructions from your doctor, or the instructions inside the pack on how to take it.
Each tablet or capsule contains 10mg, 20mg or 40mg of omeprazole. Liquid omeprazole comes labelled as either 2mg/1ml or 4mg/1ml.
The usual dose to treat:
- indigestion is 10mg to 20mg a day
- heartburn and acid reflux is 20mg to 40mg a day
- stomach ulcers is 20mg to 40mg a day
- Zollinger-Ellison syndrome is 20mg to 120mg a day
Doses are usually lower for children and people with liver problems.
Changes to your dose
Sometimes your doctor will increase your dose of omeprazole if it is not working well enough.
Depending on the reason you take omeprazole, you may take a higher dose to begin with, usually for a few weeks.
After this, your doctor may recommend that you take a lower dose.
How to take it
You’ll usually take omeprazole once a day, first thing in the morning. It will not affect your stomach, so you can take it with or without food.
If you take omeprazole twice a day, take 1 dose in the morning and 1 dose in the evening.
Swallow tablets and capsules whole with a drink of water or squash.
If you have problems swallowing capsules, most brands of omeprazole capsules are easy to open. This means you can empty the granules inside and mix them into a small amount of water or squash. You could also sprinkle them on soft food, such as yoghurt or apple puree.
Talk to your pharmacist if you're not sure whether you can open your capsules.
Omeprazole also comes as a tablet that melts in your mouth.
You can buy omeprazole 20mg tablets from pharmacies and supermarkets. You cannot buy omeprazole capsules, they are prescription only.
Omeprazole tablets that you buy from pharmacies or supermarkets can be taken by adults for up to 14 days.
Liquid omeprazole can be prescribed by a doctor for children and people who cannot swallow capsules or tablets.
If you or your child is taking omeprazole as a liquid, it will usually be made up for you by your pharmacist. It will come with a syringe or spoon to help you take the right amount. If you do not have a syringe or spoon, ask your pharmacist for one. Do not use a kitchen teaspoon because it will not measure the right amount.
How long to take it for
If you bought the medicine yourself from a pharmacy or supermarket, you can take it for up to 14 days. If you feel no better after taking omeprazole for 14 days, tell your doctor. They may want to do tests to find out what's causing your symptoms or change you to a different medicine.
Depending on your condition or the reason you're taking omeprazole, you may only need it for a few weeks or months. Sometimes, you might need to take it for longer, even for many years.
Some people do not need to take omeprazole every day and take it only when they have symptoms.
Once you feel better (often after a few days or weeks), you can stop taking it.
But taking omeprazole for a short time to treat symptoms is not suitable for everyone. Talk to your doctor about what's best for you.
If you forget to take it
If you usually take it once a day, take the missed dose as soon as you remember. If it’s 12 hours or less to your next dose, do not take it.
If you usually take it twice a day, take the missed dose as soon as you remember. If it’s 4 hours or less to your next dose, do not take it.
Do not take 2 doses to make up for a forgotten one.
If you forget doses often, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicine.
Usually, you can stop taking omeprazole without reducing your dose first. But if you've been taking omeprazole for a long time, speak to your doctor before you stop taking it. Stopping suddenly could make your stomach produce a lot more acid, and make your symptoms come back.
Reducing the dose gradually before stopping completely will prevent this happening.
It's very unlikely that taking 1 or 2 extra doses by accident will cause any problems.
But you should check if you are worried.
You take more than your prescribed dose and have any of the following symptoms:
- feeling sick
- being sick
- feeling dizzy
- stomach pain
If you need advice for a child under the age of 5 years, call 111.
Common side effects
These common side effects of omeprazole happen in more than 1 in 100 people. There are things you can do to help cope with them.
If this advice does not help and any of these side effects continue to bother you, tell your doctor or pharmacist.
Serious side effects are rare and happen in less than 1 in 1,000 people.
Call a doctor or contact 111 straight away if:
- your skin becomes more yellow (although this may be less obvious on brown or black skin), your pee becomes darker and you feel more tired – these can be signs of liver problems
- you get joint pain along with a red skin rash, especially on parts of your body exposed to the sun, such as your arms, cheeks and nose – these can be signs of a rare condition called subacute cutaneous lupus erythematosus. This can happen even if you have been taking omeprazole for a long time
- severe or persistent diarrhoea – this can be a sign of an inflamed bowel
If you need advice for a child under the age of 5 years, call 111.
Serious allergic reaction
In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to omeprazole.
If you take omeprazole for more than 3 months, the levels of magnesium in your blood may fall.
Low magnesium can make you feel tired, confused, dizzy and cause muscle twitches, shakiness and an irregular heartbeat. If you get any of these symptoms, tell your doctor.
Taking omeprazole for more than a year may increase your chances of certain side effects, including:
- bone fractures
- gut infections
- vitamin B12 deficiency – symptoms include feeling very tired, a sore and red tongue, mouth ulcers and pins and needles
If you take omeprazole for longer than 1 year, your doctor will regularly check your health to see if you should carry on taking it.
It's not known if omeprazole works less well the longer you take it.
If you feel like omeprazole is not working any more, talk to your doctor.
Omeprazole and stomach cancer
There is some research to suggest that taking medicines to reduce stomach acid, like PPIs and H2 blockers, may slightly increase the chance of developing stomach cancer. It also suggested that it could be more likely in people taking them for longer than 3 years. But studies involving more people need to be done to be sure that PPIs and H2 blockers cause stomach cancer, rather than something else causing it.
PPIs, like most medicines, have side effects so it's best to take them for the shortest time possible.
It’s also important to speak to your doctor if you notice any of these symptoms which can be signs of stomach cancer:
- having problems swallowing (dysphagia)
- feeling or being sick
- feeling full very quickly when eating
- losing weight without trying
Speak to your doctor or pharmacist if you are concerned.
Other side effects
These are not all the side effects of omeprazole. For a full list, see the leaflet inside your medicine packet.
Omeprazole is safe to take during pregnancy.
However, it may be better to try to treat indigestion without taking medicine. You could try eating smaller meals more often, and avoiding fatty and spicy foods. Sitting up straight when you eat will also take the pressure off your stomach.
If you get symptoms at night, you could prop your head and shoulders up when you go to bed. This helps to stop stomach acid coming up while you sleep.
If lifestyle changes do not work then omeprazole may be recommended for you.
Omeprazole and breastfeeding
If your doctor or health visitor says your baby is healthy it is OK to take omeprazole while you’re breastfeeding.
There is a little information available which shows that omeprazole passes into breast milk in tiny amounts, but your baby will not absorb a lot into their body.
It is unlikely that omeprazole will cause any side effects in your baby.
Omeprazole and fertility
There's no clear evidence to suggest that taking omeprazole will reduce fertility in either men or women.
But speak to a pharmacist or your doctor if you're trying to get pregnant. They may want to review your treatment.
- trying to get pregnant
Some medicines and omeprazole can affect each other and make it more likely that you'll have side effects or stop one of the medicines working properly.
Tell your doctor if you're taking these medicines before you start omeprazole treatment:
- heart medicines, such as digoxin
- cilostazol, a medicine that treats peripheral arterial disease (PAD)
- antifungal medicines, such as itraconazole, ketoconazole, posaconazole and voriconazole
- methotrexate, a medicine that treats psoriasis and rheumatoid arthritis
- HIV medicines
- phenytoin, an epilepsy medicine
- rifampicin, an antibiotic
- clopidogrel and warfarin, medicines to prevent or treat blood clots
These are not all the medicines that may not mix well with omeprazole. For a full list, see the leaflet inside your medicine packet.
Taking omeprazole with painkillers
It's best to take ibuprofen with, or just after, a meal so it does not upset your stomach.
Mixing omeprazole with herbal remedies or supplements
Do not take St John's wort, the herbal remedy for depression, while you're taking omeprazole. It may stop omeprazole working as well as it should.
There's not enough information to say that other complementary medicines and herbal remedies are safe to take with omeprazole. They're not tested in the same way as pharmacy and prescription medicines. They're generally not tested for the effect they have on other medicines.
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