Four serious side effects of omeprazole as NHS issues warning for common medicine

The NHS has issued a stark warning to anyone taking the medication omeprazole, over concerns around long-term use of the drug.

Omeprazole is the most commonly prescribed drug in the UK, with as many as 73 million NHS prescriptions being dispensed in England between 2022 and 2023.

It it mostly used to treat symptoms like heartburn and acid reflux, and is often prescribed alongside other medications that are known to come with a risk of stomach ulcers, like naproxen or ibuprofen.

The medication reduces the amount of stomach acid produced by the body by turning off the 'proton pumps' in the stomach's lining that release acid. This reduction in stomach acid can support in healing stomach ulcers and reduce symptoms like heartburn and reflux.

Around 15 percent of the UK population takes omeprazole (Jeffrey Greenberg/Universal Images Group via Getty Images)

Side effects of omeprazole

While omeprazole can be a lifeline for patients who need it, there are a number of possible side effects that must be considered before taking the drug.

Common side effects include stomach pain, headaches, nausea and vomiting. Users might also experience digestive issues, such as constipation or diarrhoea and excessive flatulation.

However, there are four significantly more serious side effects that are much less common that anyone taking the drug should be aware of.

One serious side effect is having very low levels of vitamin B12, which can lead to tiredness, dizziness, muscle twitches or weakness, according to the NHS. Another is weakened bones, which causes a higher risk of breaking if you suffer a fall or injury.

Users should also be wary of potential allergic reactions, which can cause a swollen tongue and throat, a raised itchy rash or difficulty breathing.

The NHS has issued a warning (Getty Stock Images)

Meanwhile, the fourth possible serious side effect is developing a type of lupus that causes rashes and joint pain.

While these side effects are relatively rare, your chance of developing them does increase if you take omeprazole for a long time, classed as a year or more by the NHS.

Omeprazole warning from the NHS

The NHS has now put out a warning to anyone who is using the drug for heartburn or reflux if they purchased the medication without a prescription.

They wrote: "Do not take omeprazole for longer than two weeks if you bought it without a prescription. See a GP if your symptoms get worse or do not get better."

In addition to the increased risk of side effects, there is also the concern that masking certain symptoms could prevent the diagnosis of certain illnesses that could be causing the symptoms.