Inositol

Inositol supplementation · Myo-Inositol · D-Chiro-Inositol

Snapshot

Indications	Contraindications
Polycystic ovary syndrome¹ Insulin resistance¹ Ovulation rate¹ Menstrual regularity^1–6 Gestational diabetes prevention⁷ Autoimmune thyroiditis with selenium⁸ Acne and hirsutism in PCOS⁹	Bipolar disorder¹⁰ Under 18 years of age¹⁰

Inositol is a vitamin-like sugar alcohol found in cereals, corn, legumes, and meat, and myo-inositol acts as an intracellular mediator of the insulin signal⁷. Supplementation rests on that insulin-sensitizing effect.^{1, 2, 7, 11} Its uses follow: polycystic ovary syndrome (PCOS), where the typical patient is a woman with insulin resistance^{1, 2}; prevention of gestational diabetes^{7, 11}; autoimmune thyroiditis alongside selenium⁸; and acne and hirsutism in PCOS. People also take it for mood, though a guideline taskforce did not support monotherapy for unipolar depression¹².

In PCOS, an umbrella review of meta-analyses found moderate-quality evidence for lower testosterone and insulin resistance and for more ovulation, with no high-quality evidence¹. Compared with metformin, a meta-analysis found no significant difference in body mass index, fasting insulin, or the insulin resistance index¹³. Gestational diabetes prevention rests on low-to-very-low certainty evidence from small trials, mostly in Italy⁷. In assisted reproduction, meta-analyses disagree: one found no benefit for oocyte and embryo quality¹⁴, another found higher mature-oocyte and fertilization rates¹⁵. A 2026 international Delphi consensus endorsed myo-inositol for acne and hirsutism in PCOS, but this is expert agreement, not a trial result¹⁶. Many products list inositol, mainly as powders and capsules, as myo-inositol alone or combined with D-chiro-inositol; see Form comparison.

Trials have studied myo-inositol in pregnancy for gestational diabetes prevention, even though some product labels advise against use in pregnancy⁷.

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

99 sources, 79 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources