Supplements and Methotrexate.
Methotrexate, sold under the brand names Maxtrex, Metoject, Nordimet, Zlatal, is a disease-modifying antirheumatic drug.
Methotrexate is a disease-modifying antirheumatic drug (DMARD). It is used at low doses (typically 15 to 25mg once weekly) for rheumatoid arthritis, psoriasis, and some inflammatory bowel indications. Higher doses are used for certain cancers. The dosing schedule is the most important safety point. Methotrexate is weekly, not daily. Daily dosing errors have caused fatalities. Folic acid 5mg taken on a different day reduces methotrexate side effects without blunting efficacy. This is NICE-endorsed and standard UK rheumatology practice. The interaction with NSAIDs is the one the BNF flags. Chronic NSAID use reduces methotrexate clearance and raises toxicity risk, particularly in patients with reduced renal function. Folate supplementation matters. Methylated folate at low daily doses is acceptable, but folate timing and form should be discussed with the rheumatology team. Alcohol intake is the other significant variable for hepatic safety. Pregnancy is contraindicated, with strict contraception requirements and a three to six month washout period before conception.
Below are the 3 documented pairs we have explicitly assessed against Methotrexate in the Distil database: 3 amber. The pairs cluster around 2 mechanisms: Antifolate antagonism and Immunosuppression caution. 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
Antifolate antagonism
This one depends entirely on why methotrexate is being taken, so do not change anything yourself. For rheumatoid arthritis, psoriasis or similar conditions, low weekly methotrexate is very often prescribed alongside folic acid on purpose: the folate reduces sickness, mouth ulcers and liver-enzyme problems without stopping the methotrexate from working, and it is usually taken on a different day from the methotrexate. The picture is different for high-dose methotrexate used in cancer treatment, where folate and a related rescue drug are timed precisely by the cancer team and you should never add or adjust folate around it. If you take methotrexate, let whoever prescribes it set your folate, rather than starting or stopping it on your own.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Immunosuppression caution
Bifidobacterium longum 1714 is a live bacterium, and for most people it is safe. Methotrexate dampens the immune system, and in people whose defences are significantly weakened there have been rare cases of a probiotic organism getting into the bloodstream and causing an infection. At the usual low weekly doses for arthritis or psoriasis this risk is small, but it is sensible to check with your specialist before starting this strain, and to avoid it if you are seriously unwell in hospital or have a central line or drip.
Probiotics are live bacteria or yeast, and for most people they are safe. Methotrexate dampens the immune system, and in people whose defences are significantly weakened there have been rare cases of the probiotic organism getting into the bloodstream and causing an infection. At the usual low weekly doses for arthritis or psoriasis this risk is small, but it is sensible to check with your specialist before starting a probiotic, and to avoid them if you are seriously unwell in hospital or have a central line or drip.
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.
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