Supplement · Grade A

Myo-Inositol and medications.

Every documented pair, every citation. Below: 2 documented pairs grouped by mechanism.

Myo-Inositol is in the Distil supplement database, evidence Grade A. The page below lists every medication we have explicitly assessed it against.

Myo-inositol is a sugar alcohol your cells use as a messenger in insulin and hormone signalling, which is why it has become a mainstay for polycystic ovary syndrome. This is one of the few supplements here at Grade A, specifically for PCOS, with Grade B evidence for anxiety and insulin sensitivity on top. For PCOS the studied approach is 1,800 to 4,000mg myo-inositol combined with d-chiro-inositol in a 40:1 ratio, which works better than myo-inositol alone; general use sits around 2 to 4g daily. Benefits extend to insulin sensitivity, female fertility and egg quality, and some trials put its anxiety effect in the range of low-dose SSRIs, though that comparison should be read cautiously. On interactions it is clean: no significant drug interactions are documented. The main side effect is stomach upset, easily managed by splitting the dose. A practical note: give it three months of consistent use, since hormonal and metabolic changes are gradual.

Below are the 2 documented pairs we have explicitly assessed for Myo-Inositol: 2 amber. The pairs cluster around 2 mechanisms: Additive glucose lowering and Reduced mood-stabiliser effect. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not listed here is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by medication, and the missing-item form at the bottom of the page routes any uncatalogued medication into our next curation pass.

Documented interactions

Last reviewed 14 June 2026. Each interaction below is assessed against PubMed-indexed evidence.

Additive glucose lowering

Amber Does interact with Metformin?

Myo-inositol may improve how your body responds to insulin and gently lower blood sugar. Metformin also lowers blood sugar, so taking the two together may add up. The combination is generally manageable and is sometimes used on purpose, but it is sensible to monitor your blood glucose when you start myo-inositol or change the dose, and your doctor may adjust the metformin if needed.

Evidence: Limited human data, based on case reports and a known mechanism.

PMID 27808588 · PMID 36703143 · PMID 23764390 · BNF: Metformin

Reviewer-flagged: awaiting clinical-reviewer sign-off.

Reduced mood-stabiliser effect

Amber Does interact with Lithium carbonate?

One of the leading explanations for how lithium steadies mood is that it lowers myo-inositol levels in the brain. Taking supplemental myo-inositol could in theory work against this and may reduce how well lithium controls mood, and there is a published report of mania in a person taking inositol. If you take lithium, do not start myo-inositol without discussing it with the doctor who manages your lithium first.

Evidence: Based on an established mechanism, with no direct study of this exact combination yet.

PMID 12826261 · PMID 29339929 · PMID 18256615 · PMID 8633705 · BNF: Lithium

Reviewer-flagged: awaiting clinical-reviewer sign-off.

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. Use the checker below to surface any medication, and submit a missing item if you take something we have not catalogued.

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