Omeprazole 20mg (Generic Losec)

What is omeprazole?

Omeprazole is a medication that reduces the amount of acid your stomach produces. It belongs to a group of treatments called proton pump inhibitors (PPIs) and is one of the most widely prescribed medicines in the UK.

What is omeprazole used for?

Omeprazole is often used to treat conditions like persistent acid reflux, heartburn, indigestion, and gastro-oesophageal reflux disease (GORD). This is a common, chronic condition where stomach acid repeatedly rises into your food pipe (oesophagus), causing symptoms like acid reflux and heartburn.

It can also be used for gastroprotection if you’re taking non-steroidal anti-inflammatory drugs (NSAIDs), like aspirin, ibuprofen, and naproxen.

While omeprazole can also be used to treat things like stomach ulcers, we’re unable to prescribe it for this reason from our clinic.

How does omeprazole work?

Your stomach lining contains tiny pumps called proton pumps, which release acid to help digest food. When too much acid is produced, it can irritate the stomach lining, the food pipe, and the gut, causing symptoms like acid reflux.

Omeprazole works by blocking these pumps, directly reducing how much acid your stomach makes. This gives the lining of your stomach and food pipe time to heal, helping to relieve symptoms.

How long does it take for omeprazole to work?

Omeprazole starts reducing acid within one to two hours of your first dose. Most people notice an improvement in their symptoms within two to three days of taking it regularly. For conditions like GORD, it can take longer to feel the full benefit.

How effective is omeprazole?

Omeprazole is very effective at relieving the symptoms of acid reflux and GORD.

In a large clinical trial, nearly half of patients taking omeprazole 20mg once a day had complete heartburn relief within just one week, rising to 74% reporting no heartburn by day 27. This was significantly better than lower doses and far more effective than a placebo.

What is the maximum dose of omeprazole in 24 hours?

The standard dose is 20mg (one capsule) once a day. Although the dose can sometimes be increased for certain medical conditions, this is outside the scope of our clinic. Don’t take more than your prescribed dose without speaking to a medical professional first.

How to use omeprazole

Always take omeprazole exactly as your doctor or pharmacist has told you. Your dose and how long you take it for will depend on what you’re treating. As a general guide:

• If you’re taking omeprazole for persistent acid reflux, heartburn, indigestion, or GORD, take one 20mg capsule once a day, in the morning.
• If you’re taking omeprazole for gastroprotection from NSAIDs, take one 20mg capsule per day, in the morning, for four to eight weeks.

Tips for taking omeprazole

When taking omeprazole, keep in mind:

• You can take it with food or on an empty stomach.
• Swallow the capsule whole with half a glass of water. Don’t chew or crush it, as this can stop the medicine from working properly.
• Take it at the same time each day to keep levels consistent.
• If you miss a dose, take it as soon as you remember. If it’s nearly time for your next dose, skip the missed one and carry on as normal. Don’t take two doses at once.
• Keep taking omeprazole for the full course, even if you feel better. Stopping early can allow symptoms to return.

Omeprazole side effects

Like all medicines, omeprazole can cause side effects, though not everyone gets them. Common side effects (may affect up to one in 10 people) include:

• headaches
• diarrhoea
• stomach pain
• constipation
• wind
• nausea or vomiting
• benign (non-harmful) growths in the stomach lining

How long do omeprazole side effects last?

Most common side effects are temporary and tend to improve within a few days to a week. If side effects persist or become bothersome, speak to your doctor or pharmacist. They may adjust your dose or suggest a suitable alternative.

How to manage omeprazole side effects

• Headaches: Rest and stay hydrated. Painkillers like paracetamol can help if needed.
• Diarrhoea: Drink plenty of fluids to stay hydrated. If it's severe or lasts more than a few days, speak to your pharmacist.
• Stomach pain: Try taking omeprazole with food if the pain is bothering you and avoid rich or spicy meals.
• Constipation: Drink more water and eat a diet rich in fibre. Regular light exercise can also help.
• Wind: Eat slowly, avoid fizzy drinks, and try not to eat large meals late in the evening.
• Feeling or being sick: Take omeprazole before a light meal and avoid lying down straight after eating.
• Benign growths in the stomach lining: These aren't harmful and typically go away on their own. Your doctor will monitor them if needed.

When to avoid omeprazole

Don’t take omeprazole if you’re allergic to omeprazole, other proton pump inhibitors like pantoprazole, lansoprazole, rabeprazole, or esomeprazole, or any of the other listed ingredients.

Omeprazole interactions

Don’t take omeprazole if you’re taking nelfinavir (a medicine used to treat HIV).

Omeprazole can also interact with other medicines. Let your doctor or prescriber know if you’re taking any of the following:

• clopidogrel (a blood thinner)
• methotrexate
• warfarin and other anticoagulants
• antifungals like ketoconazole, itraconazole, or voriconazole
• HIV medicines
• digoxin
• rifampicin
• St John's Wort

Is it safe to use omeprazole long-term?

Omeprazole is generally intended for short-term use. Most people will start on a higher dose which is then reduced or stopped once symptoms have improved. There are some conditions that require longer-term treatment, but your prescriber will advise you on this.

If you do need to take omeprazole for an extended period, it’s worth knowing that long-term use may:

• increase the risk of a gut infection called Clostridioides difficile, which can cause severe diarrhoea
• mask the symptoms of stomach cancer, which is why it’s important to have any persistent or unusual symptoms investigated before starting treatment
• increase the risk of bone fractures, particularly in older people
• increase the risk of pneumonia
• lower magnesium levels in the body, which can cause tiredness, muscle weakness, dizziness, and in some cases, more serious effects like convulsions or an irregular heartbeat

If you have any concerns about taking omeprazole long-term, speak to your GP or prescriber. Never stop taking it without their guidance, as symptoms can return quickly.

How to get omeprazole

If you’re interested in omeprazole to help with your acid reflux, heartburn, indigestion, GORD, or for gastroprotection if you’re taking NSAID medication, simply complete a short online consultation with us.

You’ll answer some questions about your symptoms and medical history, which will then be reviewed by our expert clinicians. If you’re suitable, we’ll deliver your treatment quickly and discreetly straight to your door, completely hassle-free.

Can you buy omeprazole over the counter?

Omeprazole 10mg is available to buy over-the-counter at pharmacies without a prescription. The 20mg and 40mg strengths are prescription-only.

Can you get omeprazole on the NHS?

Yes, omeprazole is available on the NHS, and it’s one of the most prescribed NHS medications in the UK.

If your GP has prescribed omeprazole, Chemist4U can make getting your repeat prescriptions easier than ever. Simply nominate us as your pharmacy and we'll deliver your medication straight to your door, discreetly and completely free of charge.

Download the Chemist4U app today and never miss a prescription again.

Alternatives to omeprazole

If omeprazole isn't suitable for you, there are several alternatives worth discussing with your GP or pharmacist.

Other proton pump inhibitors (PPIs):

• lansoprazole
• pantoprazole
• esomeprazole
• rabeprazole

Antacids:

• aluminium hydroxide
• magnesium carbonate
• magnesium trisilicate
• magnesium hydroxide
• calcium carbonate
• sodium alginate
• sodium bicarbonate

Brands like Gaviscon usually contain sodium alginate, calcium carbonate, and sodium bicarbonate. Rennie contains calcium carbonate and magnesium carbonate.

While they can provide quick relief for mild heartburn and indigestion, they don't treat underlying conditions the way PPIs do.

The right choice depends on your condition, how severe your symptoms are, and any other medicines you take. Speak to your GP, pharmacist, or use our online consultation service to find the best option for you.

Frequently asked questions about omeprazole

Does omeprazole cause constipation?

Constipation is a common side effect of omeprazole. If you notice changes to your bowel habits while taking it, drinking more water and making sure you include fibre-rich foods in your diet can help.

If your constipation is severe or isn’t improving, speak to your pharmacist for advice.

Does omeprazole cause weight gain?

Omeprazole can potentially cause weight gain, but only with long-term use. A study found that people taking PPIs like omeprazole, rabeprazole, or lansoprazole for a long time were linked to weight gain.

The study looked at two groups of people: those with GORD who were taking PPIs and those without GORD who were not. People in the PPI group had been taking their medication for around two years on average. Both body weight and body mass index (BMI) increased in this group.

Can you take omeprazole when you’re pregnant?

Omeprazole is generally considered safe to take during pregnancy, but like all medications, you should always check with your GP, midwife, or pharmacist first.

Can you drink alcohol on omeprazole?

You should avoid drinking alcohol while taking omeprazole, as it can increase stomach acid and make your symptoms worse.

Are omeprazole and lansoprazole the same?

Omeprazole and lansoprazole aren’t the same medicine, but they work in a very similar way. Both are proton pump inhibitors that reduce stomach acid, and both are used to treat the same range of conditions.

Some people respond better to one over the other, so if one doesn’t work well for you, it’s worth asking about switching.

Does omeprazole help with bloating?

There isn't much evidence to suggest that omeprazole can help with bloating. That said, if your bloating is caused by excess stomach acid, like with acid reflux or indigestion, it may offer some relief.

But if your bloating is linked to other causes, like irritable bowel syndrome (IBS) or a food intolerance, omeprazole is unlikely to help.

Is omeprazole a proton pump inhibitor?

Yes, omeprazole is a proton pump inhibitor, or PPI.

Sources

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