Omeprazole belongs to a group of medications called proton pump inhibitors (PPIs). PPIs are used to treat conditions where the stomach produces too much acid, such as acid reflux and indigestion. Omeprazole comes in tablet or liquid form and helps to reduce the amount of acid in your stomach. It is available in both over-the-counter and prescription-only strengths.

Omeprazole is usually taken once or twice daily, with some people needing to take it for a few days, whereas others may need to take it for a few months or years.

Omeprazole is a proton pump inhibitor (PPI). Proton pumps are found in the lining of the stomach and make acid to help digest food. Omeprazole targets the proton pumps and blocks the enzymes responsible for producing acid. This reduces stomach acid, relieving acid reflux symptoms and treating the condition's cause.

How long does it take for omeprazole to work?

Omeprazole effectively reduces stomach acid production and works within 4 days of starting treatment, providing significant relief from symptoms like heartburn and acid reflux. Although it will reduce the amount of acid in the stomach shortly after the first dose, you will need to take it consistently to achieve the maximum benefit.

How effective is omeprazole?

Omeprazole is an effective medication that reduces stomach acid levels and is often used to treat acid reflux, indigestion, and other stomach problems. Research shows that a 20mg dose of omeprazole reduces 24-hour stomach acid levels by at least 80% in people with duodenal ulcers.

A study comparing omeprazole with lansoprazole found they were both equally effective at managing acid reflux. Research comparing omeprazole with the over-the-counter treatment Gaviscon found that, while both were effective at managing mild-to-moderate heartburn, the average number of heartburn-free days was higher in the omeprazole group.

Swallow omeprazole tablets whole with half a glass of water, with or without food. It’s usual to take omeprazole once a day for acid reflux, but for severe illness, such as ulcers caused by a bacterium called Helicobacter pylori, some people may need to take it twice a day – once in the morning and once at night.

If you have no damage to your oesophagus (food pipe), you will usually be prescribed a once daily 10mg dose of omeprazole to be taken in the morning. If there is damage to your oesophagus, then the usual dose is one 20mg omeprazole capsule per day, in the morning.

When should I take omeprazole?

Omeprazole for acid reflux is usually taken once per day. You should take omeprazole in the morning, either with food or on an empty stomach.

How long can I take omeprazole for?

You should only take omeprazole tablets for up to 4 weeks. Any longer, and you are at risk of having serious side effects.

How many omeprazole can I take a day?

You can take up to 2 omeprazole capsules a day, but this will depend on the dose you have been prescribed. If you have mild indigestion, you will likely only take one 20mg capsule a day.

Omeprazole is available in 3 doses – 10, 20, or 40mg. The dose you will be prescribed will depend on the condition it is being prescribed for and how severe it is. Your doctor will advise you on the best omeprazole dose for you and how you should take it.

Omeprazole 10mg

Omeprazole 10mg is a low-dose PPI that is used to reduce stomach acid in mild cases of heartburn, indigestion, and gastroesophageal reflux disease (GORD). It is available with a prescription from a doctor, but is also available over the counter.

Omeprazole 20mg

Omeprazole 20mg once per day for 4 to 8 weeks is the standard dose for treating acid reflux. It is available with a prescription, or you may be able to get it over the counter from a pharmacist.

Omeprazole 40mg

The highest dose of omeprazole is 40mg, and your doctor may advise you to take this dose for 8 weeks if the lower 20mg daily dose for 4 to 8 weeks has not healed your oesophagus. It is usually given for more severe cases of acid reflux and is only available with a prescription from a doctor.

Can I buy omeprazole online?

Yes, you can order omeprazole online through Superdrug Online Doctor. You will simply need to fill out a questionnaire, which is then reviewed by one of our doctors to make sure omeprazole is a suitable treatment for you. If your order is approved, your omeprazole will be sent directly to you, or to your local Superdrug Pharmacy for you to pick up.

Can I buy omeprazole over the counter?

Yes, both omeprazole 10mg and 20mg are available over the counter. They are intended to be used for a short period, usually no more than 14 days, without a prescription. If your symptoms have not improved or get worse after 2 weeks, you should speak to a doctor. They can prescribe omeprazole for longer, usually 4 to 8 weeks for acid reflux, and monitor your symptoms, or they may recommend a higher dose.

Can I get omeprazole on the NHS?

Yes, you can get omeprazole on the NHS, but you will need to make an appointment with your GP so that they can decide if it is safe and suitable for you. Depending on how severe your symptoms are, your GP will usually prescribe omeprazole for 4 to 8 weeks. If omeprazole is not right for you, they may prescribe an alternative PPI, such as lansoprazole.

Omeprazole is a very common medication that can cause side effects, although not everyone will get them.

You are more likely to have serious side effects if you are taking a high dose of omeprazole or have been taking omeprazole for a longer period of time.

Common side effects include:

• dizziness and sleepiness
• headaches
• stomach pain
• constipation
• flatulence (farting)
• nausea (feeling sick)

Uncommon side effects include:

• loss of appetite
• hair loss
• inflammation of the stomach
• taste changes

Rare side effects include:

• liver damage
• pancreatitis
• dermatological disorders

A full list of side effects can be found in the omeprazole patient information leaflet.

Why does omeprazole cause weight gain?

Omeprazole is not commonly associated with weight gain, and it is not listed as a potential side effect in the patient information leaflet. However, one study found that long-term omeprazole use (more than 2 years) resulted in an average weight increase of 6.2%. Making healthy lifestyle choices, such as getting regular exercise and eating a healthy, balanced diet, can help manage your weight while taking omeprazole and can also help reduce acid reflux. If you are concerned about weight gain and omeprazole, speak to your doctor for more advice.

Can omeprazole cause constipation?

Yes, omeprazole can cause constipation in some people. It is listed as a common side effect that can affect up to 1 in 10 people who take it.

What to do if you get side effects

Most people who take omeprazole do not get any side effects. If you do experience any of the common side effects, they usually go away when you stop taking omeprazole. If you get any serious side effects or notice that side effects continue even after you stop taking omeprazole, book an appointment to see your GP.

What are the side effects of long-term use of omeprazole?

The longer you take omeprazole, the more you are at risk of developing serious side effects. If you take omeprazole for more than 3 months, the levels of magnesium in your blood may fall. Taking omeprazole for over a year increases your chances of bone fractures, gut infections, and Vitamin B12 deficiencies.

Omeprazole may not be right for everyone. Certain conditions or medications can interact with omeprazole, making it less effective or potentially unsafe.

Omeprazole is known to interact with:

• heart medications like digoxin
• antifungal medications like itraconazole and voriconazole
• methotrexate
• HIV medications
• anti-epilepsy medications like phenytoin
• antibiotics like rifampicin
• blood thinning medications like clopidogrel and warfarin

Tell your doctor about any medication you are taking before starting your treatment with omeprazole.

Alternative acid reflux medications include:

• lansoprazole
• esomeprazole
• pantoprazole

Lansoprazole is another type of PPI that works by acting on the proton pumps in the stomach to reduce the amount of acid being produced. Lansoprazole and omeprazole are similarly effective at managing acid reflux, but lansoprazole may work slightly more quickly, with many people reporting symptom improvement within 2 to 3 days.

Esomeprazole is also available under the brand name Nexium. Esomeprazole is also a PPI with some research suggesting that it may provide a faster, stronger, and longer effect for acid reflux than omeprazole.

Pantoprazole is another example of a PPI that reduces stomach acid production to treat heartburn and indigestion. It may be the preferred choice if you are taking any medications that may interact with omeprazole, such as clopidogrel. Research shows that a once-daily 40mg dose of pantoprazole improved gastroesophageal reflux disease symptoms in 70% of people after 8 weeks.

Natural alternatives to omeprazole

If you have too much stomach acid, there are certain lifestyle and dietary changes you can make that may help without the need to take medication. These include:

• maintaining a healthy weight
• avoiding foods that make symptoms worse, like spicy and fatty foods
• avoiding caffeinated drinks, like tea and coffee
• stopping smoking
• avoiding eating at least 3 hours before going to sleep