Myo-Inositol and medications.
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 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. We do not recommend it for fertility or for general hormone balance, because no study we cite measures ovulation, conception, pregnancy or egg quality at all, and the meta-analysis behind the PCOS grade reports the testosterone reduction as a non-significant trend and androstenedione as unaffected. What that meta-analysis does establish is metabolic: fasting insulin and insulin resistance both fell. We no longer recommend it for anxiety: when the placebo-controlled trials in anxiety disorders were pooled, no significant effect was found, and the trials that did show promise used 12 to 18 grams a day, far above the usual supplement range. Two interactions are worth knowing. Myo-inositol gently lowers blood sugar, so if you take metformin or another glucose-lowering medicine it is sensible to monitor your levels when you start or change the dose. And it may work against lithium, since lithium's mood effect is thought to run partly through inositol depletion, so anyone taking lithium should treat myo-inositol as a decision for their prescriber. 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 lists the evidence its assessment drew on: some rest on studies of the exact pair, others on mechanism evidence, where a citation may support one part of the reasoning rather than the exact combination. The evidence line on each entry says which.
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, from small studies or case reports, alongside a known mechanism.
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.
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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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.
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The free checker answers one interaction question at a time. A Distil report reviews the bigger picture: your goals, diet, medications, current supplements and any blood results you provide, then shows what appears worth keeping, changing, adding or leaving out.
- what your diet already covers, so you are not adding a capsule for something food is already handling
- which evidence-graded compounds are worth considering for your goals, and which were considered but left out
- what to keep, change or stop from what you already take, plus the order to introduce anything new
- how your medications and complete supplement stack fit together, with daily timing and a clear point for reassessment
The interaction check is one section of the full report. You also get the reasoning behind each recommendation and the evidence references used.
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