What are the common side effects of omeprazole, particularly in adults and older adults with a history of gastrointestinal issues or impaired renal (kidney) or liver function?

Common Side Effects of Omeprazole

The most common side effects of omeprazole are gastrointestinal symptoms including headache, diarrhea, nausea, abdominal pain, and vomiting, which occur in up to 14% of patients and are generally mild and transient. 1, 2

Gastrointestinal Side Effects

• Headache, diarrhea, constipation, and nausea are the most frequently reported adverse effects, occurring in up to 14% of older children and adults prescribed PPIs 1
• Nausea, dizziness, headache, and diarrhea are typically mild and transient, rarely requiring dose reduction or cessation of therapy 3
• These gastrointestinal complaints represent the most commonly reported adverse effects in clinical practice 4

Serious but Less Common Side Effects

Kidney Problems

• Acute tubulointerstitial nephritis (TIN) can occur at any point during PPI therapy, presenting with decreased renal function, malaise, nausea, or anorexia 2
• Patients may present without classic extra-renal manifestations (fever, rash, arthralgia), making diagnosis challenging 2
• Discontinue omeprazole immediately if acute TIN is suspected 2

Infection Risk

• Clostridium difficile-associated diarrhea risk is increased with PPI therapy, particularly in hospitalized patients 2
• Consider this diagnosis for any diarrhea that does not improve during omeprazole therapy 2
• PPIs may increase risk of community-acquired pneumonia, gastroenteritis, and candidemia in pediatric patients 1

Bone Fractures

• Increased risk of osteoporosis-related fractures of the hip, wrist, or spine occurs with multiple daily doses taken for a year or longer 2
• Use the lowest effective dose for the shortest duration necessary 2

Autoimmune Complications

• Cutaneous and systemic lupus erythematosus have been reported, occurring as new onset or exacerbation of existing disease 2
• Subacute cutaneous lupus erythematosus (SCLE) is the most common form, typically occurring within weeks to years of continuous therapy 2
• Discontinue omeprazole if new or worsening joint pain or photosensitive rash develops 2

Laboratory Abnormalities

• Elevation of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) concentrations is the most frequently reported laboratory abnormality 4

Special Population Considerations

Elderly and Renal/Hepatic Impairment

• The frequency and spectrum of adverse events are the same in patients over 65 years as in younger patients 3
• No drug-related adverse events have been found specifically in patients with renal insufficiency 3
• Patients with severe liver failure show no unique adverse event profile, though dose reduction to 10 mg daily is recommended for hepatic impairment 3, 2

Critical Clinical Pitfalls to Avoid

• Do not use omeprazole longer than medically indicated, as risk of serious complications increases with duration of therapy 2
• Do not ignore decreased urination or blood in urine, as these may indicate tubulointerstitial nephritis requiring immediate discontinuation 2
• Do not dismiss persistent diarrhea without evaluating for C. difficile infection 2
• Monitor for neuropsychiatric symptoms in pediatric patients, as overuse in infants is particularly concerning given lack of superiority over placebo for irritability 1