AEMPS Identifies New Side Effect of Omeprazole

The December AEMPS report updated undesirable reactions of omeprazole. Which patients will have to be more careful?
AEMPS Identifies New Side Effect of Omeprazole
Leonardo Biolatto

Written and verified by the doctor Leonardo Biolatto.

Last update: 28 February, 2023

The Spanish Agency of Medicines and Health Products or AEMPS announced a new side effect of omeprazole, one of the most widely consumed drugs worldwide. It should also be noted that, beyond mass consumption, there’s a tendency for people to take it for many months. According to some surveys, the average time of consumption among patients is 2 years, at a rate of 20 mg per day.

Like any drug, omeprazole is not free of side effects. Some are better known and more expected than others, but with the passage of time and its presence in pharmacies, it’s possible to discover new undesirable effects.

In its December 2022 Monthly Safety Bulletin (article in Spanish) the AEMPS reported that tubulointerstitial nephritis is a new recognized side effect of omeprazole. The problem is that this condition can progress to kidney failure. Here’s an article in English for you.

What is omeprazole used for?

Omeprazole is a proton pump inhibitor in the stomach. Therefore, its action is to reduce the production of hydrochloric acid within the digestive system.

By inhibiting the proton pump, the pH rises and the environment becomes less acidic. It isn’t the same as other drugs considered antacids, which block the acidity already produced. In this case, the active ingredient reduces its production from the beginning.

That’s why omeprazole is considered to be very effective in treating gastritis, peptic ulcers, some cases of functional dyspepsia, and even the Helicobacter pylori infection. In itself, it’s very safe, but the prescription should not exceed 8 weeks. For two months it is still reasonably safe, but there are some consequences associated with continued and unsupervised use.

As we have already mentioned, the tendency is towards excessive consumption, even up to 2 years of daily intake. Therefore, many of the undesired reactions may be due to abuse and not to the approved use endorsed by scientific guidelines.

Automedicación con omeprazol aumenta los efectos secundarios.
Self-medication is a public health problem. It doesn’t doesn’t happen only with antacids.

Common adverse effects of omeprazole

The legal package inserts of the commercial brands that manufacture omeprazole mention the following as frequent unwanted reactions:

  • Headaches
  • Diarrhea or constipation
  • Nausea and vomiting
  • Flatulence

All these symptoms are to be expected and, although they don’t always appear, their presence is recognized by research on omeprazole. When faced with them, it’s best to consult with the doctor who prescribed the active ingredient, in order to evaluate options.

Side effects due to chronic use of the drug

The adverse effects that could appear due to the abuse of omeprazole have also been investigated. Here we include the excessive use that a large part of the population practices, through self-medication.

A 2016 report mentioned that the following are reactions attributable to chronic use:

  • Reduced effectiveness of anticoagulant and antiplatelet drugs. So it would increase cardiovascular risk.
  • Increased risk of pneumonia. As there’s less stomach acidity, bacteria face a weakened barrier that allows them to reproduce easily.
  • Hypovitaminosis. Above all, vitamin B12 deficiency is seen in chronic users who are elderly or who have concomitant diabetes mellitus.
  • Hypomagnesemia. Circulating magnesium concentration is reduced in patients taking the drug for more than 1 year.

Adverse effects not recorded in package inserts

Finally, a 2018 review found some adverse effects of the drug that aren’t listed in most package inserts, but that researchers attributed to the active ingredient:

What is the new side effect of omeprazole recognized by the AEMPS?

The AEMPS reported that tubulointerstitial nephritis is a side effect of omeprazole that we should consider. Therefore, there should be increased precaution when prescribing this drug to patients who already have a renal history.

This nephritis is an inflammation that occurs in the part of the kidney tissue between the tubules, that is, between the units responsible for forming urine. Those who suffer from it may have an increase in the amount of urine, a desire to urinate at night, lumbar pain, and blood in the urine.

Although there are other causes, in recent times it has been found that 70% of the cases are secondary to a medication. Nonsteroidal anti-inflammatory drugs are the main culprits, as well as some antibiotics (beta-lactams and ciprofloxacin).

As for omeprazole and its possibility of generating tubulointerstitial nephritis, it is expected that about 20 consumers of the drug per 100,000 suffer from it. Some have the lesion after only 15 days of use, while in others it can take 18 months for it to manifest itself.

Side effect of omeprazole.
The side effect of omeprazole on the kidneys can manifest itself with blood in the urine and pain in the regions near these organs.

How should I take the drug to prevent this effect?

The most important thing is that we shouldn’t self-medicate. Using it without medical supervision increases the chances of having adverse effects.

Therefore, even though in many countries it’s available over the counter, it’s preferable to have a prescription. In addition, the treatment plan should be limited to what is recommended by scientific guidelines. And this, in most cases, is restricted to no more than 8 weeks.

Some adverse effects are unavoidable. However, having the precautions of scientifically proven use, the risk is reduced.

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The Consequences of Excessively Taking Omeprazole
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The Consequences of Excessively Taking Omeprazole

Excessively taking omeprazole omeprazole and other proton pump inhibitors results in a number of mild adverse effects. Learn more about it!


All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.


  • Cardona-Ospina, J. A., Medina-Morales, D. A., Rodríguez-Morales, A. J., & Machado-Alba, J. E. (2016). Efectos adversos a largo plazo de los inhibidores de la bomba de protones: Perspectiva desde la medicina basada en la evidencia. Revista colombiana de Gastroenterología31(4), 403-408.
  • Forgerini, M., Mieli, S., & Mastroianni, P. D. C. (2018). Safety assessment of omeprazole use: a review. Sao Paulo Medical Journal136, 557-570.
  • Gordillo García, A. (2015). Omeprazol,¿ el opresor gástrico?.
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  • Nieto-Ríos, J. F., Ruiz-Velásquez, L. M., Álvarez, L., & Serna-Higuita, L. M. (2020). Acute interstitial nephritis. Literature review. Iatreia33(2), 155-166.
  • Perazella, M. A., & Markowitz, G. S. (2010). Drug-induced acute interstitial nephritis. Nature Reviews Nephrology6(8), 461-470.
  • Shah, N., & Gossman, W. (2019). Omeprazole.

The contents of this publication are for informational purposes only. At no time can they serve to facilitate or replace the diagnoses, treatments, or recommendations of a professional. Consult with your trusted specialist if you have any doubts and seek their approval before beginning any procedure.