Omeprazole reduces the amount of acid in your stomach. It comes as capsules, tablets and as a liquid.
It's different to esomeprazole (Nexium), which is also used to treat indigestion and heartburn.
Brand names of omeprazole include:
- Losec
- Pedippi
Uses of omeprazole
Omeprazole is used to treat:
- indigestion
- heartburn and acid reflux
- stomach ulcers
- a rare illness called Zollinger-Ellison syndrome
You can buy it in pharmacies without a prescription. But do not use it for more than 14 days.
Ask your GP for a prescription if you need:
- omeprazole for more than 14 days
- high strength omeprazole
How omeprazole works
Omeprazole is a 'proton pump inhibitor' medicine that reduces acid in your stomach.
Proton pumps are tiny substances that make acid to digest food. Omeprazole temporarily stops these pumps working.
Check if you can take omeprazole
Omeprazole can be taken by most adults including pregnant and breastfeeding women. But always check with your GP or pharmacist.
Children and babies can take it on prescription from your GP.
It may not be suitable if you:
- had an allergic reaction to other medicines in the past
- have liver problems
- have lactose intolerance
- are vegetarian or vegan, as capsules may contain gelatin
- are taking nelfinavir, for HIV infection
Urgent advice: Talk to your GP if you're:
- pregnant
- breastfeeding
- trying to get pregnant
Pregnancy and omeprazole
Omeprazole can be used during pregnancy.
But talk to your GP before you take it if you:
- are pregnant
- think you may be pregnant
- are trying to get pregnant
It's usually better to try to treat your symptoms without taking a medicine.
Your GP or midwife may suggest eating smaller meals and avoiding fatty and spicy food. They may also suggest raising the top of your bed so that your chest and head are above your waist when you sleep.
Breastfeeding and omeprazole
Omeprazole passes into breast milk. But this is not likely to affect your baby if you take omeprazole the way your GP tells you to.
Your GP can tell you if you can take omeprazole if you are breastfeeding.
If your baby is premature or has health problems, check with your GP before you take omeprazole.
Fertility and omeprazole
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 GP if you're trying to get pregnant. They may want to review your treatment.
When you start taking omeprazole
You should start to feel better within 2 to 3 days.
It may take up to 4 weeks for omeprazole to work properly. You may still have symptoms during this time.
Do not take omeprazole for longer than 14 days without checking with your GP. If you do not feel better or feel worse, talk to your GP.
How and when to take it
It's usual to take omeprazole once a day, first thing in the morning.
If you take omeprazole twice a day, take 1 dose in the morning and 1 dose in the evening.
You can take it with or without food.
Swallow tablets and capsules whole with water or juice. If you have problems swallowing, open the capsules and mix the granules with water or juice. You can also sprinkle them onto soft food.
Do not open capsules that have a special coating. Check with your pharmacist if you're not sure.
Liquid omeprazole is available on prescription for babies, children and those who cannot swallow pills.
Dose
The dose of your medicine depends on your condition.
Your GP may increase or decrease your dose to find what works best for you.
If you take too much
Emergency action required: Go to your nearest emergency department (ED) or phone a GP if:
- you have taken too much omeprazole and:
- feel dizzy or sleepy
- see double
- are slurring your words
- have diarrhoea
- pass out
If you forget to take it
If you take omeprazole once a day, take the missed dose as soon as you remember, unless it's less than 12 hours until your next dose. In that case, skip the missed dose.
If you take it twice a day, take the missed dose as soon as you remember, unless it's less than 4 hours until your next dose. In that case, skip the missed dose.
Do not take a double dose to make up for a forgotten dose.
How long you'll need to take omeprazole
Depending on your illness, you may only take omeprazole for a few weeks or months. Some people need to take it for longer, even for many years.
Long-term use
Levels of magnesium in your blood may fall if you take omeprazole for longer than 3 months.
This can make you feel tired, confused, dizzy and cause muscle twitches and an irregular heartbeat.
Taking omeprazole for more than 1 year can increase your chances of:
- bone fractures, especially if you have osteoporosis
- gut infections
- vitamin B12 deficiency
Contact your GP if you are on omeprazole for a long time and you are worried about any of these side effects.
If you've taken omeprazole for a long time, talk to your GP before you stop.
Stopping taking omeprazole
Talk to your GP if you've been taking omeprazole for a long time before you stop.
Stopping suddenly could make your stomach produce a lot more acid. It could make your symptoms come back. Reducing the dose gradually will prevent this happening.
Side effects
Most people who take omeprazole do not have any side effects.
If you do, they are usually mild and go away when you stop taking it.
Common side effects
There are things you can do to manage common side effects:
Headaches
Make sure you rest and drink fluids. Do not drink too much alcohol.
Ask your pharmacist to recommend a painkiller. Talk to your GP if the headaches last longer than a week or are severe.
Diarrhoea
Drink lots of fluids, such as water or squash, to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee.
Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.
If you take the combined contraceptive pill or the progestogen-only pill and you have severe diarrhoea for more than 24 hours, your contraception may not protect you from pregnancy. Check the pill packet for advice.
Stomach pain / Tummy cramps
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 GP.
Constipation
Try to get more fibre into your diet, 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 does not help, talk to your pharmacist or GP.
Wind
Avoid foods that cause wind, like lentils, peas, beans and onions. It might also help to eat smaller and more frequent meals, eat and drink slowly, and exercise regularly. Some pharmacy medicines, such as simeticone, may relieve the symptoms of wind.
Feeling sick or getting sick
Stick to simple meals and do not eat rich or spicy food if you feel sick (nausea) or are getting sick (vomiting).
Take omeprazole in the morning with some food. Try small, frequent sips of water if you're getting sick to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee.
If you take the combined contraceptive pill or the progestogen-only pill and you're getting sick, your contraception may not protect you from pregnancy. Check the pill packet for advice.
Feeling dizzy
Lie down until the dizziness passes, then get up slowly. Move slowly and carefully.
It's best to avoid coffee, cigarettes, alcohol and recreational drugs. If the dizziness does not get better within a couple of days, speak to your pharmacist or GP.
Tiredness
Do not drive, cycle or use tools or machinery if you're feeling this way. Try taking omeprazole 1 hour before bedtime. Cut down the amount of alcohol you drink as alcohol will make you feel more tired.
If the tiredness does not go away after 2 weeks, ask your GP for advice.
Sore mouth or throat
Paracetamol can help with the pain. For adults, gargling with warm, salty water may also help. This is not recommended for children.
Pharmacies and supermarkets sell other types of medicated lozenges that contain either a local anaesthetic or antiseptic. This may help with pain.
For a sore throat, see your GP if it does not improve after a week. You may need a different treatment.
Swollen ankles or feet
Raise your legs when you're sitting down.
Another common side effects can be itchy skin rashes. Talk to your GP or pharmacist if this or other side effects get worse or do not go away after a few days.
Serious side effects
Urgent advice: Tell your GP immediately if you have:
- joint pain and a rash on parts of your body exposed to the sun
- yellow skin, dark pee and tiredness
- skin that's red, blistering or peeling
- lost a lot of weight without trying
- dark pee or poo
- severe or constant diarrhoea
Serious allergic reaction
In rare cases omeprazole can cause a serious allergic reaction.
Emergency action required: Call 112 or 999 or go to your nearest emergency department (ED) if you:
- get a rash that's itchy, red, swollen or blistered
- are wheezing
- get tightness in your chest or throat
- have trouble breathing or talking
- have swelling in your mouth, face, lips, tongue or throat
See the patient information leaflet that comes with your medicine for a full list of side effects.
Non-urgent advice: Find your patient information leaflet
Your patient information leaflet is the leaflet that comes with your medicine. You can find a digital version of the leaflet online.
Report side effects
You can report any suspected side effects to the Health Products Regulatory Authority (HPRA): report an issue - hpra.ie
Similar medicines
If omeprazole does not work or agree with you, your GP may suggest you try another proton pump inhibitor.
These include:
- lansoprazole
- esomeprazole
- pantoprazole
- rabeprazole
These generally work in the same as omeprazole and have similar side effects.
Esomeprazole and pantoprazole are also available without a prescription from pharmacies.
Taking omeprazole with other medicines
Always tell your GP or pharmacist that you are on omeprazole before taking new medicines.
Also tell your GP or pharmacist if you are taking, have recently taken or might take any other medicines before you start taking omeprazole.
In particular, tell your GP if you're taking:
- digoxin (a heart medicine)
- other medicines that reduce the amount of acid in your stomach
- anti-fungal medicines such as itraconazole, ketoconazole or posaconazole
- methotrexate (for psoriasis and rheumatoid arthritis)
- HIV medicines
- phenytoin (an anti-epilepsy medicine)
- rifampicin (an antibiotic)
- blood thinners such as clopidogrel or warfarin
- medicines that reduce your immune system
- any cancer medicines
- antidepressants
Herbal remedies and supplements
St John's wort may stop omeprazole working as well as it should.
Tell your pharmacist or GP if you're taking herbal remedies, vitamins or supplements.
Painkillers
It's safe to take painkillers such as paracetamol or ibuprofen at the same time as omeprazole.
Talk to your GP or pharmacist or before using ibuprofen as it can upset your stomach.
Other heartburn medicines
You can take omeprazole with an antacid, for example Gaviscon.
Take the antacid 2 hours before or after your dose of omeprazole.
Food and drink
Avoid foods that make your indigestion worse, such as spicy and fatty foods.
You should also try to limit acidic foods, alcohol and drinks that contain caffeine, such as coffee, tea or cola.
If you have symptoms at night, try not to eat for at least 3 hours before you go to bed.
Fact check
This content was fact checked by a pharmacist, a GP, and the National Medication Safety Programme (Safermeds).
