The NHS website has all the latest guidance about the medication on its website
09:15, 22 Jan 2026Updated 10:50, 22 Jan 2026
People taking the medication should be aware of the side effects (stock image)(Image: Getty)
The NHS website is filled with useful information for anyone with health concerns or who is taking certain medication. While it is always wise to read the leaflet that comes with all medication, it is also worthwhile checking the latest NHS guidance. One commonly prescribed medication in the UK is omeprazole, a proton pump inhibitor (PPI), which reduces the amount of acid in your stomach.
It is typically prescribed to patients who are suffering from stomach problems, such as acid reflux, heartburn and indigestion. There are some over-the-counter versions people can buy at the pharmacy, which can only be taken for a couple of weeks, but most types are prescription-only.
Omeprazole can also be used to treat gastro-oesophageal reflux disease (GORD) and a stomach infection called Helicobacter pylori (along with antibiotics). As with most other medications, omeprazole comes with side effects, some that are more common than others and a few that are serious that people should be aware of.
Common side effects of omeprazole include:a headachestomach painfeeling sick or being sickconstipation or diarrhoeafarting more than usual
The NHS says: “Omeprazole will not usually affect your ability to drive, ride a bike or use machinery. But if you feel dizzy or have problems with your vision after taking it, wait until you no longer have these side effects.”
Speak to a pharmacist or doctor if you have any side effects that bother you or do not go away. “They may be able to give you advice about how you can reduce the side effects. Keep taking your medicine unless you’re advised not to,” the NHS adds.
Most adults and children can take prescribed omeprazole(Image: )
Serious side effects of omeprazole include:
Although most of them are uncommon, omeprazole can also sometimes trigger more serious side effects. The NHS warns: “The chance of getting serious side effects can be higher if you take omeprazole for a long time (a year or more)”.
having a very low level of vitamin B12weakened bonesan allergic reactionrashes and joint pain
A vitamin B12 deficiency can cause symptoms such as tiredness, dizziness, or muscle twitches or weakness. Having weakened bones can put you at an increased risk of breaking them more easily if you have a fall or injury.
Meanwhile, an allergic reaction (anaphylaxis) can cause symptoms such as a swollen throat or tongue, a raised, itchy rash or difficulty breathing. The medication may also cause a type of lupus that can lead to rashes (particularly on parts of the body exposed to the sun) and joint pain.
The chance of getting serious side effects can be higher if you take omeprazole for a long time(Image: )
The NHS guidance regarding these side effects includes calling 111 if “you’re taking omeprazole and think you might be having serious side effects”. It is important to keep in mind that these are not all the side effects of omeprazole.
For a full list, see the leaflet that comes with your medicine or search for your medicine on the electronic medicines compendium website. You can report any side effects you get on the Yellow Card website.