Omeprazole: uses, how to take, side effects

March 18, 2021
6 minute read

Proton Pump Inhibitors (PPIs) are some of the most commonly prescribed drugs around the world, including the UK. Chances are that you’ve already taken a PPI or will at some point in your life.

In this blog post, we turn our attention to the original, and most widely prescribed PPI – omeprazole. Roughly 31.5 million items of omeprazole were prescribed in England in 2019 alone. Educating yourself on this common drug is always recommended to ensure that you use it safely and effectively.

Before we get started, if you're in need of medication and you're struggling to get to the nearest pharmacy, or you'd simply prefer to do something better with your time, check out our blog to learn how to use Phlo to get medication delivered quickly and for free to your doorstep: Struggling to get to the nearest pharmacy?

What is Omeprazole, and What is Omeprazole Used For?

Introduced in clinical practice in 1989, omeprazole is the original Proton Pump Inhibitor. Since then, decades of clinical use have established omeprazole, as well as related drugs in this class, as safe, tolerable and effective medicines.

Omeprazole is primarily used to treat acid-related conditions, such as acid reflux and heartburn, indigestion and stomach ulcers.

Causes of Acid-Related Conditions

Let’s take a quick look at what causes acid-related conditions. As we know, the stomach produces acidic fluid, which serves a multitude of purposes: aids with digestion, absorption of nutrients, and sterilises bacteria contained in the foods we eat.

While useful, the acidic fluid produced by our stomach can also be damaging to the gastrointestinal tract, and for this reason, the human body has deployed several means of protection.

However, an excessive production of acid can overpower our protective mechanisms, which can lead to damage, unpleasant symptoms and even disease.

Acid-related conditions include:

  1. Acid reflux and heartburn. This condition is caused by stomach acid rising from the stomach and travelling up to the stomach, which can cause irritation (heartburn). Occasional acid reflux can occur after heavy or spicy meals, however if this happens repeatedly over a longer term, it’s called Gastro-Oesophageal Reflux Disease (GORD).

  1. Indigestion (Functional Dyspepsia). This is another condition that results from acid reflux or GORD. Too much acid production by the stomach can irritate your stomach lining, leading to indigestion, resulting in symptoms such as nausea, pain, an uncomfortable sensation of fullness.

  1. Ulcers (gastroduodenal ulcers). These are another consequence of oversecreting acid, which can severely damage your stomach, resulting in open sores. Ulcers can also appear in the upper intestine area called the duodenum; in which case they are referred to as duodenal ulcers.

How Does Omeprazole Work?

Omeprazole works to treat acid-related diseases by reducing the amount of acid that our stomach produces.

PPIs such as omeprazole are susceptible to being broken down by the acidic environment of the stomach, and as such, they are generally packaged in a protective way. These protective delivery mechanisms (e.g. enteric coating – a barrier that prevents disintegration in the stomach), allow a PPI such as omeprazole to travel safely through the stomach, and reach the small intestine.

Another mechanism for protection against the acidic environment of the stomach is gastro-resistant granules.

Once in the small intestine, omeprazole is absorbed, and circulated back into the stomach, where it binds directly to the source of gastric acid – the proton pumps located on activated parietal cells.

Omeprazole binds to the proton pump and inhibits further acid secretion – hence the name “Proton Pump Inhibitor”.

This inhibition is irreversible, meaning that acid secretion can be suppressed for up to 36 hours, until the body produces new proton pumps.

How to Take Omeprazole

How you take omeprazole depends on the reason why you’re taking it. Generally, omeprazole is taken once a day in the morning, and it can be taken with or without food. In other situations, your GP might recommend that you take omeprazole twice daily, in which case you should take it once in the morning, and once at night.

Different dosages of omeprazole are appropriate depending on the condition that is being treated:

  • For indigestion, common dosages are 10-20mg of omeprazole a day.
  • For acid reflux and heartburn, common dosages are 20-40mg of omeprazole a day.
  • For stomach ulcers, common dosages are 20-40mg of omeprazole a day.

In some cases, your GP might recommend that you start taking a higher dosage of omeprazole initially for a few weeks, after which your dosage will decrease. Alternatively, you might start taking omeprazole twice a day, then after a few weeks only take it once a day.

While omeprazole rarely produces side effects, you may experience stomach aches and nausea

Side Effects of Omeprazole

Omeprazole is regarded as a highly tolerable and safe medicine to take. However, omeprazole is still a medicine, and like most other medicines, will come with some side effects.  

The good news is that the side effects produced by omeprazole are rare, and most people will not experience them. Even if you do happen to experience side effects from taking omeprazole, these will most likely be mild, and will cease after you stop taking the medicine.  

Side effects of omeprazole can include:

Nausea and feeling sick- If you experience nausea, try taking omeprazole with food.  

Vomiting or diarrhoea - Speak to your pharmacist or doctor first and try to drink more fluids to replenish what you have lost.  

Stomach pain – Speak to your pharmacist or doctor, and try to eat more slowly, and have smaller and more frequent meals.  

Flatulence – reduce foods that might cause wind and try to have smaller, more frequent meals.

Constipation – Get more fibre into your diet and try to exercise more .

Headaches – Rest and get plenty of fluids, and speak to your GP or pharmacist if symptoms persistpersist.  

In addition, some people might also experience dizziness or sleepiness, while others might struggle to fall asleep.  

Omeprazole with Other Medicines, Pregnancy and Alcohol

It’s important to let your GP and pharmacist know that you are taking omeprazole, as it can interact with, or be affected by several other medicines. These include heart medication (digoxin), antifungal medicines, HIV medicines, anti-epileptic medicines (phenytoin), blood thinners (warfarin, clopidogrel), antibiotics such as rifampicin.  

A common herbal remedy that interacts with many medicines is St. John’s Wort, which can stop omeprazole from working as well as it should.  

If you are pregnant or breastfeeding, omeprazole is still safe to take, but it’s generally a good idea to try to manage your symptoms without resorting to taking omeprazole.  

Alcohol doesn’t interact with or affect the way in which omeprazole works, but it’s a good idea to not drink too much if you’re taking omeprazole. Alcohol consumption stimulates further acid secretion from your stomach, which can worsen your symptoms.

For more information on omeprazole, please visit the NHS page.  

Got a question about omeprazole? Get in touch with our friendly and helpful pharmacy team for free advice and guidance!

Content last reviewed on:
August 15, 2023
Next review date:
August 15, 2025
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