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Supplements

Should I take inositol if I have PCOS?

Myo-inositol with D-chiro-inositol in a 40:1 ratio is among the better-studied non-prescription options for ovulatory function in PCOS.

Reviewed by Lunara Expert Advisory Panel · May 2026

Inositols act as second messengers in insulin signalling. In PCOS, where insulin resistance is common, randomised trials of myo-inositol have reported improved ovulation rates, more regular cycles and better insulin markers over three to six months.

The 40:1 myo to D-chiro ratio mirrors the ratio found in healthy human plasma and is the ratio used in most modern trials. Typical dosing is 2,000 mg of myo-inositol twice daily.

Inositol is not a substitute for a PCOS diagnosis or for prescription treatment where it is indicated. It sits alongside clinical care, not instead of it.

The short version

  • Most-studied protocol: 4,000 mg myo-inositol daily in a 40:1 ratio.
  • Reported effects on cycle regularity typically emerge around month three.
  • Mild GI upset is the most commonly reported side effect.

When to talk to a clinician

  • You suspect PCOS but have never been formally evaluated.
  • You take metformin or other insulin-sensitising medication.
  • Cycles remain absent after six months of consistent use.

Related answers

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Cycles shorter than 21 days, longer than 35 days, or varying by more than 7–9 days between cycles are generally considered irregular.

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Most fertility-related nutrients are studied over three months, matching the roughly 90-day maturation window for eggs and sperm.

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Educational information only. Ask Lunara is a search layer over expert-reviewed content and does not provide diagnosis or personal medical advice. These statements have not been evaluated by the FDA. Always talk with your healthcare provider about your own situation.