OMEPRAZOLE: WHY IT WORKS BRILLIANTLY FOR SOME AND NOT FOR OTHERS
Omeprazole is one of the most commonly prescribed medications in the UK. It’s used to reduce stomach acid and is widely given for reflux, indigestion, gastritis and ulcer prevention.
For many people, it brings rapid relief. For others, symptoms linger, return quickly when treatment stops, or never fully resolve.
What’s less often discussed is that people process Omeprazole very differently, and that difference isn’t random.
Why Response to Omeprazole Varies So Much
Omeprazole belongs to a group of medications called proton pump inhibitors (PPIs). These drugs reduce acid production by acting on acid-secreting cells in the stomach.
To do this effectively, Omeprazole must be:
Absorbed properly
Metabolised at the right speed
Maintained at a therapeutic level
Genetic differences in drug metabolism can significantly influence this process.
As a result, the same dose can be:
Highly effective for one person
Too weak or too strong for another
This helps explain why symptom control and side effects vary so widely.
When Omeprazole Doesn’t Fully Do the Job
Omeprazole may not feel effective if you:
Still experience reflux or heartburn despite daily use
Need increasing doses for the same relief
Relapse quickly when you stop
Take it long-term without a clear plan
In some cases, the issue isn’t the diagnosis or adherence – it’s how your body handles the drug.
Side Effects and Long-Term Use
PPIs are generally well tolerated, but long-term use has raised questions around:
Digestive changes
Nutrient absorption
Rebound acid symptoms when stopping
Some people also report headaches, bloating or a “heavy” stomach feeling. These effects may be influenced by how slowly or quickly the drug is broken down.
How Pharmacogenomic (PGx) Testing Fits In
Pharmacogenomic (PGx) testing looks at genes involved in drug metabolism, including those relevant to proton pump inhibitors like Omeprazole.
Certain genetic variants can result in:
Faster breakdown of Omeprazole, reducing effectiveness
Slower breakdown, increasing exposure and side effects
Understanding this can help explain why standard dosing doesn’t suit everyone.
For Clinicians
Clinical Considerations
Omeprazole is primarily metabolised by CYP2C19
Genetic variation in this enzyme affects plasma levels and acid suppression
Rapid metabolisers may experience reduced symptom control
Poor metabolisers may have higher exposure at standard doses
PGx-informed dosing and PPI selection is supported by international guidelines
Why PGx Is Useful in Practice
Helps explain incomplete response or treatment failure
Supports rational dose adjustment or alternative PPI selection
Particularly useful in long-term PPI users
Can reduce unnecessary dose escalation
For Patients
Why This Matters for You
If Omeprazole hasn’t worked as expected, it doesn’t mean your symptoms aren’t real – and it doesn’t mean you need to stay on a medication that isn’t helping properly.
PGx testing can help you and your clinician:
Understand how your body processes PPIs
Decide whether Omeprazole is the right choice
Explore alternatives with more confidence
When to Consider PGx Testing
You may want to consider testing if:
Omeprazole hasn’t relieved your symptoms
You’ve been on PPIs long-term
Symptoms return quickly when you stop
You want a more personalised approach to treatment
A More Individual Approach to Acid Suppression
Omeprazole is a highly effective medication – when it’s the right fit.
But standard dosing doesn’t account for individual biology.
Mantara’s Pharmacogenomic (PGx) test supports a more personalised approach, helping patients and clinicians make informed decisions about PPI choice, dosing and long-term use.