What are the adverse effects of Omeprazole (Proton Pump Inhibitor)?

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Last updated: March 8, 2025View editorial policy

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From the Guidelines

Omeprazole can cause several negative effects with both short and long-term use, including increased risk of vitamin B12, magnesium, and calcium deficiencies, kidney disease, dementia, and certain infections, and it is recommended to use the lowest effective dose for the shortest duration necessary, typically not exceeding 8 weeks without medical supervision, as supported by recent studies 1.

Adverse Effects of Omeprazole

The adverse effects of omeprazole can be categorized into short-term and long-term effects. Common short-term side effects include:

  • Headache
  • Nausea
  • Diarrhea
  • Stomach pain
  • Flatulence These side effects typically resolve as the body adjusts to the medication.

Long-term Effects

More concerning are the potential long-term effects of omeprazole, which include:

  • Increased risk of vitamin B12, magnesium, and calcium deficiencies that can lead to anemia, muscle weakness, and bone fractures
  • Increased risk of kidney disease
  • Increased risk of dementia
  • Increased risk of certain infections like Clostridium difficile and pneumonia due to reduced stomach acid allowing bacterial overgrowth Omeprazole can also interact with other medications, reducing their effectiveness.

Recommendations

When stopping omeprazole after long-term use, acid rebound can occur, where stomach acid production temporarily increases above normal levels. To minimize the risks associated with omeprazole, it is recommended to use the lowest effective dose for the shortest duration necessary, typically not exceeding 8 weeks without medical supervision, as supported by recent studies 1. It is also essential to discuss any concerns about side effects with a healthcare provider.

Interactions with Other Medications

Omeprazole can interact with other medications, such as clopidogrel, and reduce their effectiveness. The FDA advises that healthcare providers avoid the use of clopidogrel in patients with impaired CYP2C19 function due to known genetic variation or due to drugs that inhibit CYP2C19 activity, such as omeprazole 1. Consideration may be given to the use of H2 antagonists as an alternative to PPIs in the setting of dual-antiplatelet therapy.

From the FDA Drug Label

Omeprazole delayed-release capsules can cause serious side effects, including: • A type of kidney problem (tubulointerstitial nephritis). • Diarrhea. • Bone fractures. • Certain types of lupus erythematosus.

The adverse effects of Omeprazole (Proton Pump Inhibitor) include:

  • Kidney problems: A type of kidney problem called tubulointerstitial nephritis
  • Diarrhea: Increased risk of getting severe diarrhea, which may be caused by an infection (Clostridium difficile) in the intestines
  • Bone fractures: Increased risk of fractures of the hip, wrist, or spine with long-term use
  • Lupus erythematosus: Certain types of lupus erythematosus or worsening of existing lupus 2

From the Research

Adverse Effects of Omeprazole

The adverse effects of omeprazole are reported in several studies, including:

  • Gastrointestinal complaints such as nausea and diarrhea 3
  • Elevation of serum aspartate aminotransferase and alanine aminotransferase concentrations 3
  • Diarrhea, headache, dizziness, flatulence, abdominal pain, and constipation 4

Common Adverse Effects

Some common adverse effects associated with omeprazole therapy include:

  • Gastrointestinal symptoms such as nausea and diarrhea
  • Laboratory abnormalities such as elevation of serum aspartate aminotransferase and alanine aminotransferase concentrations

Comparison with Other Treatments

Omeprazole is compared with other treatments in terms of adverse effects, including:

  • Omeprazole plus amoxicillin appears to be better tolerated than triple therapy 5
  • Omeprazole is similar to misoprostol and superior to ranitidine in its ability to heal NSAID-induced peptic ulcers and erosions, and superior to misoprostol, ranitidine or placebo in its ability to prevent relapse 4

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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