Acid reflux is one of the most common digestive complaints in the UK. For many people it's an occasional nuisance, but when symptoms become frequent or persistent, a proton pump inhibitor like omeprazole is often the treatment that brings lasting relief. It's one of the most widely used acid-reducing medicines in the country, available both over the counter and on prescription.
This guide explains how omeprazole works for acid reflux, how long it takes to have an effect, and when and how to take it. It also covers side effects, longer-term use, the alternatives worth knowing about, and the symptoms that mean you should speak to a pharmacist or GP rather than self-treat.
What Is Acid Reflux, and When Is Omeprazole Used?
Acid reflux happens when acid from your stomach travels back up into your oesophagus, the tube that connects your throat to your stomach. The most familiar symptom is heartburn, a burning feeling in the chest, often after eating or when lying down. You might also notice an unpleasant sour taste, a sensation of food coming back up, or a persistent cough.
When reflux happens regularly over a longer period, it's known as gastro-oesophageal reflux disease, or GORD. Omeprazole is commonly used for frequent or persistent reflux and heartburn, for GORD, and to help heal inflammation of the oesophagus caused by acid. It's also used for stomach and duodenal ulcers, and alongside antibiotics to treat ulcers linked to Helicobacter pylori infection. Occasional, mild heartburn can usually be managed with an antacid rather than omeprazole.
How Does Omeprazole Work?
Omeprazole belongs to a group of medicines called proton pump inhibitors (PPIs). Your stomach lining contains cells with tiny "pumps", known as proton pumps, that release the acid your stomach uses to digest food. Omeprazole works by blocking these pumps, which reduces the amount of acid your stomach produces.1
Lowering stomach acid does two things. It eases the symptoms that acid causes, such as heartburn and a sour taste, and it gives an irritated or inflamed oesophagus the chance to heal. Omeprazole doesn't neutralise acid that's already there in the way an antacid does, which is why it isn't designed for instant relief. Instead, it reduces how much acid is made in the first place.
How Long Does Omeprazole Take to Work?
Omeprazole doesn't work straight away. Most people start to notice an improvement in their symptoms within one to four days of starting treatment, and it can take a few days of regular dosing to feel the full effect.1 This is normal and isn't a sign that the medicine isn't working.
Because the effect builds gradually, omeprazole is best taken consistently every day rather than only when symptoms flare. Clinical trials have found that a daily dose provides early and sustained relief of heartburn in people with reflux.2 If you're using omeprazole bought from a pharmacy and your symptoms haven't improved after two weeks, you should speak to a pharmacist or GP rather than continuing on your own.
When and How to Take Omeprazole
Omeprazole is usually taken once a day. The best time to take it is in the morning, around 30 to 60 minutes before breakfast, as it works most effectively when taken before food.1 Capsules and tablets should be swallowed whole with a drink of water.
Doses commonly come in 10mg, 20mg and 40mg strengths. The 20mg dose is the usual starting point for adults with reflux, while higher doses may be prescribed for more severe symptoms or to heal oesophagitis. The lower-strength versions you can buy from a pharmacy are intended for short-term use, whereas a prescription allows for a longer, supervised course where it's needed. Always follow the dose on the label or the advice given by your prescriber.
Omeprazole Side Effects
Most people tolerate omeprazole well, and many experience no side effects at all. When they do occur, the common ones (affecting up to 1 in 10 people) are usually mild and tend to settle as your body adjusts. These include:
- Headache
- Diarrhoea or constipation
- Stomach pain or wind
- Feeling or being sick
Serious side effects are uncommon, but it's worth being aware of the risks linked to longer-term use. Taking omeprazole for an extended period can lower the level of magnesium in your blood, which the MHRA has highlighted as a recognised effect of PPIs.3 Long-term use has also been associated with low vitamin B12 levels and a small increase in the risk of bone fractures.1 If you develop symptoms that concern you, such as muscle twitching, persistent tiredness, or a rash, speak to your GP or pharmacist.
How Long Can You Take Omeprazole?
This depends on why you're taking it. Omeprazole bought without a prescription is intended for short-term use only, generally no more than 14 days. If your symptoms persist beyond that, it's important to see a GP so the cause can be looked into properly.5
When prescribed, omeprazole is often given as a course of four to eight weeks for reflux or GORD, after which treatment is reviewed.4 If symptoms return, the guidance is to use the lowest dose that keeps them under control, and some people use it only when they need it. Anyone taking omeprazole for a long time should have their treatment reviewed regularly. It's also best not to stop suddenly after prolonged use, as symptoms can temporarily rebound; your prescriber can advise on reducing the dose gradually.
Are There Alternatives to Omeprazole?
Omeprazole is one of several options for managing acid-related symptoms:
- Antacids neutralise stomach acid that's already present, giving fast but short-lived relief. Some, such as those containing alginates, form a protective barrier that helps stop acid splashing up. They're well suited to occasional heartburn.5
- H2 blockers (for example, famotidine) reduce acid production in a different way to PPIs and can be an option where a PPI isn't suitable.5
- Other PPIs, such as pantoprazole, work in the same way as omeprazole and may be tried if one PPI doesn't agree with you. Omeprazole is also sold over the counter as Pyrocalm.
- Lifestyle measures can make a real difference alongside treatment, including eating smaller meals, avoiding known trigger foods, not eating late at night, and maintaining a healthy weight.
You can find the full range of treatments on our acid reflux page, including omeprazole.
When to Seek Advice
Omeprazole is suitable for managing many cases of reflux, but some symptoms need to be checked by a healthcare professional first. Speak to a GP, or seek urgent advice, if you:
- Have difficulty or pain when swallowing
- Are losing weight without trying to
- Vomit blood, or pass black or tarry stools (seek urgent medical attention)
- Keep getting symptoms despite a course of treatment
- Are over 55 and experiencing persistent indigestion or reflux for the first time
These can sometimes point to a condition that needs investigation rather than self-treatment, and current guidance recommends referral in these situations.4
Frequently Asked Questions
How long does omeprazole take to work?
Omeprazole isn't a fast-acting medicine. Most people notice their symptoms easing within one to four days, and it can take a few days of taking it regularly to feel the full benefit. If you're using omeprazole bought from a pharmacy and there's no improvement after two weeks, speak to a pharmacist or GP.
When is the best time to take omeprazole?
Omeprazole is usually taken once a day in the morning, around 30 to 60 minutes before breakfast, as it works best when taken before food. Swallow the capsule or tablet whole with a drink of water rather than chewing it.
Can you take omeprazole long term?
It depends on why you're taking it. Omeprazole bought without a prescription is meant for short-term use only, usually no more than 14 days. When prescribed, it's often given as a course of a few weeks and then reviewed, and anyone using it long term should have their treatment checked regularly, as extended use is linked to lower magnesium and vitamin B12 levels and a small increase in fracture risk.
Can you take antacids with omeprazole?
Antacids work differently to omeprazole and act much faster, so some people use one for occasional breakthrough symptoms while omeprazole builds up its effect. If you plan to use both regularly, check with a pharmacist about how best to space them.
Can you drink alcohol while taking omeprazole?
Alcohol doesn't directly interact with omeprazole, but it can irritate the stomach and make heartburn and reflux worse. Cutting back may help your symptoms settle more quickly.
Is omeprazole safe to take during pregnancy?
Omeprazole is generally considered suitable during pregnancy when it's needed, but you should always speak to your GP or pharmacist before starting it so they can advise on the most appropriate option for you.
What is the difference between omeprazole and lansoprazole?
Both are proton pump inhibitors that reduce stomach acid in the same way, and they're similarly effective for reflux and heartburn. If one doesn't suit you, a prescriber may suggest trying the other. Pharmica stocks both omeprazole and lansoprazole.
What should I do if omeprazole isn't working?
If your symptoms haven't improved after a two-week over-the-counter course, or they return once you stop, see a GP rather than continuing to self-treat. They can check the cause, review the dose, and rule out anything that needs further investigation. Do not ignore symptoms such as difficulty swallowing, unintended weight loss, or vomiting blood, which need prompt medical attention.
References
- NHS. Omeprazole: a medicine to treat heartburn and indigestion. nhs.uk/medicines/omeprazole
- Efficacy of omeprazole for the treatment of symptomatic acid reflux disease without oesophagitis. PubMed. 2000. PMID:10871975
- Medicines and Healthcare products Regulatory Agency (MHRA). Drug Safety Update: Proton pump inhibitors in long-term use, reports of hypomagnesaemia. gov.uk/drug-safety-update
- National Institute for Health and Care Excellence (NICE). Gastro-oesophageal reflux disease and dyspepsia in adults: investigation and management. CG184. nice.org.uk/guidance/cg184
- NHS. Common questions about omeprazole. nhs.uk/medicines/omeprazole
This article is intended for informational purposes only and does not replace professional medical advice. Always read the patient information leaflet supplied with your medication and speak to a healthcare professional if you have specific concerns.