Omeprazole

Sounds like 'oh-mep-ra-zole'

Key points about omeprazole

Omeprazole is used to treat and prevent problems affecting your stomach and gut, such as indigestion, reflux and ulcers.
It works by reducing stomach acid.
Omeprazole belongs to a group of medicines known as proton pump inhibitors.
It's also called Losec®.

HN 0914 young woman being counselled over the counter in pharmacy 950x690

Omeprazole reduces the amount of acid produced in your stomach. It belongs to a group of medicines known as proton pump inhibitors (PPIs).

Omeprazole is used to treat conditions associated with high levels of stomach acid, such as indigestion, reflux and ulcers. It can prevent ulcers from forming or help the healing process where damage has already occurred.
Omeprazole can be used to prevent ulcers caused by medicines such as non-steroidal anti-inflammatory drugs (NSAIDs). Examples of NSAIDs are diclofenac, ibuprofen, and naproxen.
It can also be given together with certain antibiotics to get rid of Helicobacter pylori, a bacteria found in your stomach that can cause ulcers.
For information on omeprazole in children, see omeprazole information for parents and carers.(external link)

In Aotearoa New Zealand omeprazole is available on a prescription, written by a prescriber for:

capsules (10 mg, 20 mg, 40 mg)
injection (usually used in hospital)
a liquid suspension (2 mg in 1 mL) that your pharmacy can make for you.

Small packs of enteric-coated tablets (10 mg, 20 mg) and capsules (20 mg) are available to buy over the counter at a pharmacy. Read more about getting omeprazole without a prescription.

March 2025 update: The Teva brand of omeprazole capsules will look different.

The 20 mg and 40 mg capsules were changed in October 2024. The 10 mg capsules will change over in March 2025. The bottle and label will also look slightly different.

The company that makes the product is the same and the capsules have the same amount of active ingredients and will work in your body the same way.

Image credit: Omeprazole new look(external link), Pharmac

Avoid long-term use of omeprazole

If you’ve bought the medicine from a pharmacy or supermarket you can take it for up to 14 days. If the symptoms return or you don’t feel any better after taking omeprazole, talk to your healthcare provider to find out what’s causing your symptoms. There are usually other medicines you can try.

If you don’t need it, omeprazole shouldn't be taken long term because of the possible side effects. There may be a small increased risk of bone fractures, chest infection, gut infection and nutrient deficiencies such as low magnesium and vitamin B12.

If you’ve been prescribed omeprazole for reflux by your healthcare provider, have been taking it for longer than 4 to 8 weeks, and your symptoms seem to be well managed, talk to your healthcare provider about reviewing your medicine. They may recommend reducing your treatment. This could include:

reducing your daily dose of omeprazole
taking omeprazole only when you experience the symptoms of heartburn and reflux (also known as on-demand therapy)
stopping treatment completely, as your symptoms may not return – it may be best to reduce the dose over a few weeks before stopping.

Other information

Having an endoscopy: Ask your healthcare provider 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.
Other medicines: Omeprazole interacts with some medicines, herbal supplements and rongoā Māori, so check with your healthcare provider before starting omeprazole and before starting any new products.
Pregnancy or breastfeeding: Talk to your healthcare provider if you're pregnant, planning a pregnancy or want to breastfeed.
Liquid omeprazole: Store liquid omeprazole in the fridge. If you notice any change in the appearance of the liquid (eg, cloudiness, particles, precipitation, changes in colour to orange or black, changes in smell or taste) ask your pharmacist for advice.

Like all medicines omeprazole can cause side effects, although not everyone gets them. Often side effects improve as your body adjusts to the new medicine.

Rebound acid secretion when stopping

When omeprazole is stopped, a common side effect is rebound acid secretion, where the acid secretion in your stomach increases significantly. This should return to normal within 2 weeks. Because the symptoms of rebound acid secretion are the same as for reflux (eg, indigestion, discomfort and pain in your upper stomach and chest, feeling sick and an acid taste in your mouth), it can form an ongoing loop where stopping omeprazole treatment creates the need to start it again.

Rather than restarting omeprazole, your healthcare provider may advise you to use antacids such as Acidex, Mylanta or Gaviscon. These can be effective for treating rebound acid secretion so talk to your healthcare provider if you experience it.

If you’ve been taking omeprazole long term, talk to your healthcare provider about whether they recommend you slowly reduce your dose before stopping.

Other side effects

Stomach upset, feeling sick Feeling bloated, gas in your abdomen (tummy), farting Loose stool (mild diarrhoea) Constipation	These are common when you first start omeprazole. If you feel sick, try taking omeprazole with or after a meal or snack. Tell your healthcare provider if these side effects bother you.
Signs of low magnesium, such as muscle cramps, weakness, tiredness, feeling irritable and tingling or numbness	If you take omeprazole for more than 3 months, the levels of magnesium in your blood may fall. Tell your healthcare provider if you get these side effects.
Signs of low vitamin B12 such as feeling very tired, a sore and red tongue, mouth ulcers and pins and needles.	This is most likely if you take omeprazole long term, on an ongoing basis. Tell your healthcare provider if you get these side effects.
Severe or ongoing diarrhoea (loose, watery, frequent stools)	This can be a sign of an inflamed bowel. Tell your healthcare provider immediately or phone Healthline 0800 611 116.
Fever and joint pain along with a red skin rash. Rash on parts of your body exposed to the sun, such as your arms, cheeks and nose.	Omeprazole can cause rare conditions called subacute cutaneous lupus erythematosus and drug-induced photo-sensitivity reactions. They can happen even if you have been taking omeprazole for a long time. Tell your healthcare provider immediately or phone Healthline 0800 611 116.