Medication · other antisecretory drugs and mucosal protectants

Supplements and Famotidine.

Every documented pair, every citation. Below: 3 documented pairs grouped by mechanism.

Famotidine, sold under the brand names Pepcid, Pepcidtwo, is classified under "antisecretory drugs and mucosal protectants" in the BNF.

Famotidine (UK brand names Pepcid, Pepcidtwo) sits at NHSBSA prescribing rank 71 in the 2024/25 PCA statistics. The BNF classifies it under "antisecretory drugs and mucosal protectants". This means it sits outside the high-volume therapeutic classes (statins, PPIs, ACE inhibitors, SSRIs) where supplement-interaction surfaces are densely studied, and the published evidence base for specific supplement pairs is correspondingly thinner. Where interactions are documented in the Distil database, they are listed below with their clinical-reference citation; where pairs have not been explicitly assessed, the missing-item form at the bottom of the page routes them into our next curation pass. Anyone combining Famotidine with a regular supplement stack benefits from explicit GP or pharmacist awareness rather than assuming no interaction exists by default.

Below are the 3 documented pairs we have explicitly assessed against Famotidine in the Distil database: 3 amber. 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

Amber Iron

Famotidine reduces stomach acid, and non-haem iron absorbs less well in a low-acid stomach, so it can lower iron uptake from a standard ferrous sulphate or ferrous fumarate tablet. The effect tends to be less marked than with a PPI like omeprazole, because famotidine suppresses acid less completely. Iron bisglycinate is less pH-dependent, and taking iron in the morning on an empty stomach with vitamin C helps. Always confirm ferritin is in the deficient range before supplementing iron.

PMID 41060063 · BNF: Famotidine · BNF: Ferrous-sulphate

Amber Vitamin B Complex

A B complex contains vitamin B12, and long-term famotidine (an acid-reducing H2 blocker) lowers stomach acid and can slow how well your body absorbs B12 from food. The effect is smaller than with stronger acid-blockers, but over years it can add up. If you take famotidine long term, it is reasonable to ask your GP about checking your B12 occasionally.

PMID 24327038 · BNF: Famotidine

Amber Vitamin B12

Long-term famotidine reduces stomach acid, which slows how well your body pulls vitamin B12 out of food. The effect is smaller than with stronger acid blockers like omeprazole, and it only matters after a couple of years of daily use. Good to know: a B12 supplement gets around this entirely, because supplement B12 does not need stomach acid to be absorbed. If you take famotidine daily for years, it is worth asking your GP for a B12 blood test.

PMID 24327038 · BNF: Famotidine

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.

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For adults over 18. This tool gives evidence-graded information, not medical advice. Always discuss changes with your GP, especially if you take any medication, are pregnant, breastfeeding, or have a serious health condition.

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Distil's interactions database is reviewed and updated every quarter. We grade evidence transparently and publish our methodology, including every database change, at /about/methodology. This tool is information, not a substitute for clinical judgement. If you take medication and supplements together, your GP or pharmacist can review your full regimen against your medical history. If you want a full personalised stack reasoned against this same database, the Distil report is the next step up.