Omeprazole

Omeprazole reduces the amount of acid your stomach makes. It's a widely-used treatment for indigestion and acid reflux. It's also taken to prevent and treat stomach ulcers.  

Sometimes, omeprazole is taken for a rare illness 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 (this is made to order).

All types of omeprazole are available on prescription. You can buy the lowest-strength 10mg tablets and capsules from pharmacies.

  1. Key facts

    • 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 headache, 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, don't take it for longer than 2 weeks without checking with a doctor.
    • Omeprazole is also called by the brand names Losec and Losec MUPS.
  2. Who can take omeprazole

    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.

    Some omeprazole capsules contain gelatin so they're not suitable for vegetarians and vegans.

    Some omeprazole capsules contain small amounts of lactose, so they may be unsuitable for people with a digestive problem called lactose intolerance.

    To make sure omeprazole is safe for you, tell your doctor if you have:

    • had an allergic reaction to omeprazole or any other medicine
    • liver problems
  3. How and when to take

    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 one dose in the morning and one dose in the evening.

    The usual dose to treat:

    • indigestion is 10mg to 20mg a day
    • acid reflux disease 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 onto soft food, such as yogurt or apple puree.

    Don't 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

    Liquid omeprazole can be prescribed by a doctor and made to order for children and people who cannot swallow capsules or tablets. It will 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.

    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?

    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. However, taking omeprazole in this way isn't suitable for everyone. Talk to your doctor about what is 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 often forget doses, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways that are suitable for you and your medicines.

    What if I take too much?

    Taking too much omeprazole by accident may cause side effects such as:

    • feeling dizzy or sleepy
    • seeing double
    • slurring your words
    • diarrhoea
    • passing out   

    If this happens, call your doctor straight away, or go to the nearest hospital accident and emergency (A&E) department.

    If you can, take the box or leaflet inside the packet plus any remaining medicine with you to the hospital.

  4. Side effects

    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:

    • headaches
    • diarrhoea
    • stomach pain
    • constipation
    • wind
    • feeling sick or vomiting

    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.

    Serious side effects

    Serious side effects are rare and happen in less than 1 in 1,000 people. Tell 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 that can happen weeks even years after taking omeprazole
    • yellow skin, dark pee and tiredness. These can be signs of liver problems. It happens in less than 1 in 1,000 people taking omeprazole
    • reddening, blisters and peeling of the skin. There may also be severe blisters and bleeding in the lips, eyes, mouth, nose and genitals. This could be Stevens-Johnson syndrome or toxic epidermal necrolysis. It happens in less than 1 in 10,000 people taking omeprazole

    Serious allergic reaction

    The warning signs of a serious allergic reaction are:

    • getting a skin rash that may include itchy, red, swollen, blistered or peeling skin
    • wheezing
    • tightness in the chest or throat
    • having trouble breathing or talking
    • swelling of the mouth, face, lips, tongue or throat

    A serious allergic reaction is an emergency. Contact a doctor straight away if you think you or someone around you is having a serious allergic reaction.

    These are not all the side effects of omeprazole. For a full list see the leaflet inside your medicine packet.

  5. How to cope with side effects

    What to do about:

    • 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.
    • diarrhoea and vomiting – drink plenty of water in small, frequent sips. It may also help to take oral rehydration solutions. You can buy these from a pharmacy or supermarket to prevent dehydration. Do not take any other medicines to treat diarrhoea or vomiting without speaking to a pharmacist or doctor. 
    • constipation – eat more high-fibre foods such as fresh fruit and vegetables and cereals, and drink plenty of water. Try to exercise more regularly, 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 help with wind, such as charcoal tablets or simethicone.

    You can report any suspected side effects to a UK safety scheme.

  6. Pregnancy and breastfeeding

    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, not eating fatty and spicy foods, and raising the head of your bed a little.

    If lifestyle changes don't work, you may be recommended a medicine like omeprazole.

    Omeprazole and breastfeeding

    Omeprazole passes into breast milk, but only in small amounts which aren't harmful to the baby.

    However, if your baby is premature or has health problems, check with your doctor first.

    Tell your pharmacist or doctor if you are pregnant or breastfeeding.

  7. Cautions with other medicines

    Some medicines and omeprazole can interfere with each other and make it more likely that you will have side effects.

    Tell your doctor if you're taking these medicines before you start omeprazole treatment:

    • heart medicines such as cilostazol and digoxin
    • anti-fungal medicines such as itraconazole, ketoconazole, posaconazole and voriconazole
    • methotrexate (treats psoriasis and rheumatoid arthritis)
    • HIV medicines
    • phenytoin (an anti-epilepsy medicine)
    • rifampicin (an antibiotic)
    • blood thinning medicines, such as clopidogrel and warfarin    

    Mixing omeprazole with herbal remedies and supplements

    Don't take the herbal remedy for depression, St John's wort, at the same time as 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 and supplements.

  8. Common questions