Conditions
You started taking a PPI for reflux. That was years ago. You’re still on it, and you’re not sure what your stomach is actually doing at this point. The Heidelberg test can show you.
Written by Michael D. Erdman, MBBS · Reviewed May 2026
You started the PPI for a few weeks. That was five years ago. Every time you try to stop, the symptoms come back worse than before. So you keep taking it. Nobody has measured whether you actually need it. Nobody has checked what your stomach is doing underneath the suppression.
PPIs work by shutting down the proton pumps in your parietal cells. These are the mechanisms that produce hydrochloric acid. When you take a PPI every day for months or years, your stomach’s acid output drops to a fraction of what it would normally be.
Your body notices. It responds by producing more gastrin, the hormone that signals the stomach to make acid. Gastrin levels rise. The parietal cells that aren’t being suppressed try to compensate. When you eventually stop the PPI, those elevated gastrin levels can cause a rebound surge of acid that feels worse than what you started with. Many people interpret this as proof they still need the medication. In reality, it’s a temporary withdrawal effect.
After years on PPIs, the question becomes: what is my stomach actually doing? Is it still overproducing acid? Has it adapted to the suppression? Have the parietal cells been affected by years of reduced activity? Is the original problem even still present?
These are important questions, and they don’t have easy answers without a direct measurement. Blood tests and symptoms can’t tell you what your acid output actually is. The only way to know is to measure it.
In 2022, the American Gastroenterological Association published a formal Clinical Practice Update on de-prescribing proton pump inhibitors. The core principle: patients should not use any medication when there is not a reasonable expectation of benefit. The update recommends regular review of ongoing PPI need, trials of dose reduction or discontinuation where no definitive indication exists, and step-down from twice-daily to once-daily dosing for most patients.
Studies consistently find that 25 to 70 percent of PPI prescriptions lack a documented clinical indication. In hospital settings, 40 to 70 percent of inpatient PPI initiations are non-guideline-concordant, and a significant proportion continue at discharge without reassessment. The American Geriatrics Society advises against scheduled PPI use beyond eight weeks in older adults.
The question these guidelines raise but do not answer: how do you determine who actually needs continued acid suppression and who does not, without ever measuring their acid?
A growing body of evidence links acid suppression to the development of allergic disease. When gastric acid is reduced, dietary proteins survive the stomach intact and can trigger immune responses in the small intestine. A study of 792,130 children found that infants exposed to acid-suppressing medication had significantly higher rates of food allergy, drug allergy, and allergic rhinitis. An analysis of eight million insurance records in Austria found that patients prescribed acid inhibitors were nearly twice as likely to subsequently need anti-allergy medication.
The mechanism is the same whether acid is suppressed by a drug or absent due to disease: without adequate acid, the stomach’s role as a digestive immune filter is compromised. For more on this connection, see our page on food sensitivities and stomach acid.
The Heidelberg test measures your stomach acid in real time. For someone who has been on long-term PPIs, this provides something nothing else can: a clear picture of what your stomach is actually doing right now.
The test shows whether your acid production is normal, reduced, or absent. It shows whether your stomach can respond to a challenge and recover. It gives you and your practitioner real data to make informed decisions about whether to continue, taper, or change course.
If you’ve been on PPIs for a long time and you’re wondering what’s actually happening in your stomach, a Heidelberg test can give you a definitive answer. About an hour, no sedation, results the same day.
See if the Heidelberg test is your next step.