Supplements and Lansoprazole.
Lansoprazole, sold under the brand names Zoton, Prevacid, is a proton pump inhibitor (PPI): it suppresses gastric acid production by inhibiting the H+/K+ ATPase pump.
Lansoprazole is a proton pump inhibitor. It sits second in England's PPI prescribing volume, after omeprazole. The drug binds irreversibly to the H+/K+ ATPase in gastric parietal cells, suppressing acid secretion for around 24 hours per dose. What matters for supplement interactions is downstream. Sustained low gastric acid changes how four nutrients are absorbed. Vitamin B12 needs acid to dissociate from food protein. Magnesium drops slowly enough that hypomagnesaemia from PPI use is in NICE guidance and warrants annual electrolyte checks. Iron absorption falls, especially the non-haem iron in plant sources. And calcium has its own bone fracture signal in long observational cohorts. NICE recommends reviewing PPI indication annually and stepping down where possible. The interaction surface here is absorption, not CYP metabolism. If you have been on lansoprazole more than two years, ask for a B12 and magnesium check at your next blood draw.
Below are the 8 documented pairs we have explicitly assessed against Lansoprazole in the Distil database: 7 amber and 1 green. The pairs cluster around 1 mechanism: Absorption interference. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not on this list is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by supplement, and the missing-item form at the bottom of the page routes any uncatalogued supplement into our next curation pass.
Documented interactions
Absorption interference
Calcium carbonate, the most common supplement form, needs stomach acid to dissolve, so lansoprazole can reduce how much calcium you absorb from it. Calcium citrate does not depend on stomach acid and is the better choice on a long-term PPI. If you stay on carbonate, taking it with food rather than on an empty stomach also helps.
Non-haem iron from supplements absorbs less well in a low-acid stomach, so chronic lansoprazole use reduces iron uptake from a standard ferrous sulphate or ferrous fumarate tablet. Iron bisglycinate is less pH-dependent and a better choice on a long-term PPI. Taking iron in the morning on an empty stomach with vitamin C also helps. Always confirm ferritin is in the deficient range before supplementing iron.
Long-term lansoprazole use is associated with low blood magnesium in about 1 in 5 chronic users. Supplementing magnesium is generally helpful, but if you have heart, kidney, or muscle symptoms on long-term lansoprazole, ask your GP for a magnesium blood test.
Long-term lansoprazole use is associated with low blood magnesium in about 1 in 5 chronic users. Supplementing magnesium is generally helpful, but if you have heart, kidney, or muscle symptoms on long-term lansoprazole, ask your GP for a magnesium blood test.
Long-term lansoprazole use is associated with low blood magnesium in about 1 in 5 chronic users. Magnesium L-threonate is still elemental magnesium, so supplementing is generally helpful, but if you have heart, kidney, or muscle symptoms on long-term lansoprazole, ask your GP for a magnesium blood test.
A B complex contains vitamin B12, and long-term lansoprazole use reduces stomach acid and slows how well your body absorbs B12 from food. After about two years of daily use, B12 deficiency becomes notably more likely, and a standard B complex dose may not fully offset it. If you take lansoprazole long term, ask your GP about an annual B12 blood test.
Long-term lansoprazole use reduces stomach acid and slows how well your body absorbs vitamin B12 from food. After about two years of daily use, B12 deficiency becomes notably more likely. If you take lansoprazole long term, ask your GP about an annual B12 blood test.
This is worth knowing rather than a problem. Vitamin C is less stable when the stomach is less acidic, and acid-lowering medicines like lansoprazole modestly reduce the amount of vitamin C in your blood. The drop is small, it is the medicine affecting the vitamin rather than the other way round, and it does not stop you taking a vitamin C supplement. If anything, people on long-term acid-lowering treatment are the ones who may benefit most from keeping a good vitamin C intake.
What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope (food-supplement interactions only; for drug-drug interactions, the BNF is authoritative). Use the checker below to surface any supplement, and submit a missing item if you take something we have not catalogued.
How we grade severity, choose what's in scope, and what we exclude.
Every call on this page is reasoned. We publish the full rubric for severity tiers, the medication inclusion logic, the evidence grades we accept, and what we deliberately leave out. About three thousand words. Worth reading once if you use this tool more than occasionally.
Read the full methodologyWant this checked across everything you take?
This page checks the pairs you enter. The personalised Distil report goes further:
- the same graded, cited interaction check across your whole stack, not just the pairs you thought to type in
- where your current routine may be leaving you short of your goals
- the evidence-backed compounds worth adding, and the ones worth dropping
It's a paid report: £79, or £49 for the first 25 customers. The interactions check is one section of it, and you can read a real one in full before you buy.
See a real sample reportSomething missing?
If a supplement or medication you take isn't in our autocomplete, tell us. We go through what people flag every week and add what's missing.