- It's usual to take omeprazole once a day in the morning.
- For severe illness, you can take it twice a day - in the morning and in the evening.
- Common side effects include headaches, diarrhoea and stomach pain. These tend to be mild and go away when you stop taking the medicine.
- If you're self-treating with omeprazole, do not take it for longer than 2 weeks without checking with a doctor.
- Omeprazole is also called by the brand names Losec and Losec MUPS.
Omeprazole can be taken by adults, including pregnant and breastfeeding women.
Omeprazole can 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 had an allergic reaction to omeprazole or any other medicines in the past
- 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.
It's usual to take omeprazole once a day, first thing in the morning. It doesn't upset the 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.
How much to take
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.
Tablets and capsules
Each tablet or capsule contains 10mg, 20mg or 40mg of omeprazole.
Swallow tablets and capsules whole with a glass of water or juice.
If you have problems swallowing capsules, you can open some brands of omeprazole capsules and mix the granules inside with a small amount of water or fruit juice, or sprinkle them on soft food, such as yoghurt or apple puree.
Do not open capsules that have a special coating (like those made by Dexel). 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 10mg tablets and capsules from pharmacies.
They're the same as omeprazole 10mg tablets and capsules that you get on prescription, but they're meant to be taken only by adults, and only for up to 4 weeks.
Liquid omeprazole can be prescribed by a doctor and made to order for children and people who cannot swallow capsules or tablets.
It'll come with a syringe or spoon to help you take the right amount. If you don't have a syringe or spoon, ask your pharmacist for one.
Do not use a kitchen teaspoon as it will not give the right amount.
Will my dose go up or down?
Sometimes your doctor will increase your dose of omeprazole if it isn't working well enough.
Depending on the reason you take omeprazole, you may take a higher dose to begin with, usually for a month or two.
After this, your doctor may recommend that you take a lower dose.
How long will I take it for?
If you bought the medicine yourself from a pharmacy, tell your doctor if you feel no better after taking omeprazole for 2 weeks.
They may want to do tests to find out what's causing your symptoms or change you to a different medicine.
Depending on your illness 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 don't 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 in this way isn't suitable for everyone. Talk to your doctor about what's best for you.
What if I forget to take it?
- If you usually take it once a day, take the missed dose as soon as you remember, unless it's within 12 hours of your next dose, in which case skip the missed dose.
- If you usually take it twice a day, take the missed dose as soon as you remember, unless it's within 4 hours of your next dose, in which case skip the missed dose.
Do not take a double dose to make up for a forgotten dose.
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.
What if I take too much?
It's very unlikely that taking 1 or 2 extra doses by accident will cause any problems.
But you should check with your doctor if you have taken too much and have any of these symptoms:
- flushed skin
- feeling sweaty
- a fast heartbeat
- feeling sleepy
- blurred vision
- feeling confused or agitated
Most people who take omeprazole don't have any side effects. If you do get a side effect, it's usually mild and will go away when you stop taking omeprazole.
Common side effects
Common side effects, which happen in more than 1 in 100 people, include:
- feeling sick
- being sick (vomiting) or diarrhoea
- stomach pain
Omeprazole may also make you feel dizzy or sleepy. Some people might find it difficult to fall asleep.
It may also cause an itchy or lumpy skin rash, or make your feet or ankles swell.
Talk to your doctor or pharmacist if the side effects bother you or don't go away.
Serious side effects
Serious side effects are rare and happen in less than 1 in 1,000 people.
Call a doctor straight away if you have:
- joint pain along with a red skin rash, especially in 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
- yellow skin, dark pee and tiredness - these can be signs of liver problems
Serious allergic reaction
In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to omeprazole.
Call 999 or go to A&E if:
- you get a skin rash that may include itchy, red, swollen, blistered or peeling skin
- you're wheezing
- you get tightness in the chest or throat
- you have trouble breathing or talking
- your mouth, face, lips, tongue or throat start swelling
You could be having a serious allergic reaction and may need immediate treatment in hospital.
These are not all the side effects of omeprazole. For a full list, see the leaflet inside your medicines packet.
You can report any suspected side effect to the UK safety scheme.
What to do about:
- headaches - make sure you rest and drink plenty of fluids. Do not drink too much alcohol. Ask your pharmacist to recommend a painkiller. Headaches should usually go away after the first week of taking omeprazole. Talk to your doctor if they last longer than a week or are severe.
- feeling sick - try taking omeprazole with or after a meal or snack. It may also help if you don't eat rich or spicy food.
- being sick (vomiting) or diarrhoea - drink plenty of water by having small frequent sips to avoid dehydration. Signs of dehydration include peeing less than usual or having strong-smelling pee. Do not take any other medicines to treat diarrhoea or vomiting without speaking to a pharmacist or doctor.
- stomach pain - try to rest and relax. It can help to eat and drink slowly and have smaller and more frequent meals. Putting a heat pad or covered hot water bottle on your stomach may also help. If you are in a lot of pain, speak to your pharmacist or doctor.
- constipation - get more fibre into your diet, such as fresh fruit and vegetables and cereals, and drink plenty of water. Try to exercise, for example, by going for a daily walk or run. If this doesn't help, talk to your pharmacist or doctor
- wind - steer clear of foods that cause wind, like pulses, lentils, beans and onions. It might also help to eat smaller and more frequent meals, eat and drink slowly, and exercise regularly. Some pharmacy remedies, such as simethicone, may relieve symptoms of wind.
Usually, omeprazole is safe to take during pregnancy and while breastfeeding.
If you're pregnant, it's always better to try to treat indigestion without taking a medicine.
Your doctor or midwife will first advise that you try to ease your symptoms by eating smaller meals more often and avoiding fatty and spicy foods.
They may also suggest raising the head of your bed 10 to 20cm by putting something under your bed or mattress, so that your chest and head are above your waist. This helps stop stomach acid travelling up towards your throat.
If lifestyle changes don't work, you may be recommended a medicine like omeprazole.
For more information about how omeprazole can affect you and your baby during pregnancy, read this leaflet on the Best Use of Medicines in Pregnancy (BUMPS) website.
Omeprazole and breastfeeding
Omeprazole is safe to take while you're breastfeeding. It passes into breast milk, but only in small amounts that aren't harmful to the baby.
But if your baby is premature or has health problems, check with your doctor first.
Tell your doctor if you're:
- trying to get pregnant
Some medicines and omeprazole can interfere with each other and make it more likely that you'll have side effects.
Tell your doctor if you're taking these medicines before you start omeprazole treatment:
- heart medicines, such as digoxin
- cilostazol (treats peripheral arterial disease)
- antifungal medicines, such as itraconazole, ketoconazole, posaconazole and voriconazole
- methotrexate (treats psoriasis and rheumatoid arthritis)
- HIV medicines
- phenytoin (an anti-epilepsy medicine)
- rifampicin (an antibiotic)
- bloodthinning medicines, such as clopidogrel and warfarin
These are not all the medicines that may not mix well with omeprazole. For a full list, see the leaflet inside your medicine packet.
Mixing omeprazole with herbal remedies and supplements
Do not take St John's wort, the herbal remedy for depression, while you're taking omeprazole.
St John's wort may stop omeprazole working as well as it should.
Tell your pharmacist or doctor if you're taking other medicines, including herbal remedies, vitamins or supplements.
How does omeprazole work?
Omeprazole is a type of medicine called a proton pump inhibitor (PPI).
Proton pumps are tiny substances in the lining of the stomach that help it make acid to digest food.
Omeprazole prevents proton pumps working properly. This reduces the amount of acid the stomach makes.
When will I feel better?
You should start to feel better within 2 to 3 days.
It may take up to 4 weeks for omeprazole to work properly, so you may still have some acid symptoms during this time.
If you're self-treating, tell your doctor if you feel no better after taking omeprazole for 2 weeks. They may want to do tests or change you to a different medicine.
Can I take painkillers with it?
It's best to take ibuprofen with, or just after, a meal so it doesn't upset your stomach.
Are there similar medicines?
There are 4 other medicines that are similar to omeprazole. They are:
Like omeprazole, these medicines are PPIs. They work in the same way as omeprazole to reduce acid in your stomach.
They generally work as well, and have similar side effects, as omeprazole. But they may be given in different doses.
Sometimes, if omeprazole doesn't work or agree with you, your doctor may suggest that you try taking another PPI.
Are there other indigestion medicines?
There are other pharmacy and prescription medicines for indigestion and heartburn.
Antacids, like calcium carbonate (Tums), sodium bicarbonate, Maalox and Milk of Magnesia, relieve indigestion and heartburn by neutralising the acid in your stomach.
They give quick relief that lasts for a few hours. They're ideal for occasional bouts of stomach acid symptoms.
Some antacids, such as Gaviscon, have an extra ingredient called alginic acid.
They work by lining your stomach so juices from it don't splash up into your foodpipe. They're especially good for relieving acid reflux.
Antacids are available from pharmacies and supermarkets.
Histamine antagonists (commonly called H2 blockers) reduce the amount of acid made in your stomach, but they do this in a different way from PPIs.
They include ranitidine (Zantac), cimetidine (Tagamet), famotidine (Pepcid) and nizatidine (Axid).
In general, PPIs like omeprazole are used first because they're better than H2 blockers at reducing stomach acid.
But if you don't get on with a PPI (for example, because of side effects), your doctor may prescribe an H2 blocker.
You can buy famotidine and ranitidine over the counter from pharmacies.
Can I take omeprazole with an antacid?
You can take omeprazole with an antacid (for example, Gaviscon) if you need to, but leave a gap of 2 hours between them.
Is omeprazole I buy the same as on prescription?
You can buy omeprazole 10mg tablets and capsules from pharmacies.
They're the same as omeprazole 10mg tablets and capsules you get on prescription, but they're meant to be taken only by adults and only for up to 4 weeks.
Higher doses of omeprazole are only available on prescription.
Is it safe to take omeprazole for a long time?
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 isn't working any more, talk to your doctor.
Does taking omeprazole for a long time cause stomach cancer?
A Hong Kong study published in 2017 suggested that people taking PPIs like omeprazole for at least 3 years have a very small increased chance of developing stomach cancer.
For every 10,000 people taking a PPI long term, it was thought an extra 4 people get stomach cancer.
But the study didn't prove that PPIs were causing stomach cancer and the results may not apply in the UK.
People who take PPIs regularly shouldn't be particularly concerned by this study.
But PPIs, like most medicines, have side effects, so it's best to take them for the shortest time possible.
Speak to your doctor or pharmacist if you're concerned.
How do I come off omeprazole?
Usually, you can stop taking omeprazole without reducing the dose first.
If you have taken 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.
Will it affect my fertility?
There's no firm 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.
Will it affect my contraception?
Omeprazole doesn't affect any type of regular contraception, including the combined pill.
It may reduce the effectiveness of one type of emergency contraception called ellaOne (ulipristal), so a different form of emergency contraceptive may be recommended instead.
Can I drive or ride a bike?
Omeprazole can make you feel dizzy, sleepy, or get blurred vision.
If this happens to you, do not drive, cycle or use machinery or tools until you feel better.
Can I drink alcohol with it?
Alcohol doesn't interfere with the way omeprazole works.
But drinking alcohol makes your stomach produce more acid than normal.
This can irritate your stomach lining and make your symptoms worse.
Can lifestyle changes help?
It may be possible to ease symptoms caused by too much stomach acid by making a few changes to your diet and lifestyle:
- maintain a healthy weight by eating healthily
- do not eat foods that can make your symptoms worse, such as rich, spicy and fatty foods, and acidic foods like tomatoes, citrus fruits, salad dressings and fizzy drinks
- cut down on caffeinated drinks, such as tea, coffee and cola, as well as alcohol and smoking
- if you have symptoms at night, try not to eat for at least 3 hours before you go to bed
- raise the head of your bed 10 to 20cm so that your chest and head are above your waist