GradedHealth

Does Inositol Help PCOS and Fertility?

Trials suggest myo-inositol can restore regular cycles and improve hormones in PCOS; proof of more pregnancies is still thin.

Published October 2026

Short answer

Limited but real promise: inositol likely improves cycle regularity and hormone and insulin markers in PCOS, and is gentler than metformin; pregnancy benefits remain uncertain. Evidence grade C (Limited). Meta-analyses of many small RCTs; downgraded for inconsistency across reviews and low to very-low certainty from risk of bias.

Key takeaways

  • Women with PCOS taking inositol were about 80% more likely to return to a regular cycle than those taking placebo [1].
  • Across trials, inositol lowered testosterone and fasting insulin and raised SHBG, working roughly as well as metformin [1][2].
  • For hard fertility outcomes the evidence is thin: a Cochrane review could not confirm more live births or pregnancies with inositol [3].
  • Inositol caused far fewer gut side effects than metformin; only a very high dose of 12 grams a day caused mild nausea or diarrhoea [4][5].

The short version

Inositol, studied mostly as myo-inositol, looks genuinely helpful for polycystic ovary syndrome (PCOS), though the clearest gains are in cycle regularity and hormone levels rather than in having a baby [6][7].

Across 26 randomised trials with 1,691 women, those taking inositol were about 80% more likely to return to a regular cycle than those taking placebo [1].

Whether that translates into more pregnancies or live births is still uncertain: a Cochrane review of 13 trials rated the evidence low to very low quality and could not confirm a benefit [3].

What the studies show

A 2023 review of 26 trials found inositol improved cycle regularity, trimmed body mass slightly, reduced free and total testosterone, and raised SHBG, the protein that binds testosterone [1].

The same review found lower fasting glucose and insulin levels with inositol, and judged it roughly equal to metformin for restoring regular cycles [1].

A 2026 umbrella review of 13 meta-analyses agreed, reporting lower luteinising hormone, lower testosterone, higher SHBG and better insulin sensitivity, plus nearly triple the ovulation rate and more than double the live-birth rate -- but it rated none of the evidence high quality [6].

Not every review is so positive: one analysis of 17 trials found almost no change in weight, glucose, insulin or most hormones, apart from androstenedione and prolactin, with wide variation between trials [8].

The review behind the 2023 international PCOS guidelines likewise called the evidence limited and inconclusive, noting possible metabolic and ovulation benefits but no clear difference from metformin for reproductive outcomes [7].

On fertility directly, the Cochrane review found a live-birth odds ratio of 2.42 with myo-inositol before IVF, but the range (0.75 to 7.83) included no effect and only 84 women contributed to that result [3].

Clinical pregnancy results were similarly inconclusive, and one apparent drop in miscarriages rested almost entirely on a single unusual trial [3].

Another review of assisted reproduction found no clear pregnancy-rate gain from inositol versus no treatment, though inositol beat metformin head-to-head for clinical pregnancy [9].

Smaller bright spots exist: myo-inositol improved egg maturity and fertilisation rates in IVF [10], and one trial of 196 women having ovulation induction with insemination reported clinical pregnancy in 18.6% with inositol versus 12.2% without, alongside lower hormone-injection doses [11].

The nuances

Trials typically used 2 to 4 grams a day of myo-inositol, often with folic acid, for three to six months [11][12][13].

The myo form, alone or with folic acid, looked better than D-chiro-inositol alone, which one umbrella review said should be used with caution [6].

Combining inositol with metformin restored regular cycles more often than metformin alone and lowered a hirsutism score in a review of six trials [13].

But metformin may have the edge for excess hair growth and waist-to-hip ratio, and one trial found inositol worked best in women of normal weight [7][12].

For tolerability, inositol wins clearly: head-to-head trials reported about five times more adverse events with metformin, mostly gut complaints, while only a very high inositol dose of 12 grams a day caused mild nausea, gas or diarrhoea [4][5].

What this means for you

If PCOS disrupts your cycles, the evidence gives real -- though still limited -- reason to discuss inositol with your doctor, especially if metformin's stomach effects bother you [1][4].

If the goal is pregnancy, go in clear-eyed: inositol may improve ovulation and related markers, but no review proves more babies yet, so it is best seen as one option within proper fertility care rather than a guaranteed fix [3][9].

People who are pregnant, breastfeeding or taking glucose-lowering medicines should talk to a doctor first. A review of inositol in pregnancy found no serious adverse events but rated the evidence low certainty, and interaction data are sparse [14].

Go deeper

  • Inositol — Myo-inositol likely helps restore regular cycles and improve testosterone and insulin markers in PCOS, with fewer gut side effects than metformin.

References

  1. Inositol is an effective and safe treatment in polycystic ovary syndrome: a systematic review and meta-analysis of randomized controlled trials.. Reprod Biol Endocrinol, 2023.
  2. Effects of myo-inositol vs. metformin on hormonal and metabolic parameters in women with PCOS: a meta-analysis.. Ir J Med Sci, 2023.
  3. Inositol for subfertile women with polycystic ovary syndrome.. Cochrane Database Syst Rev, 2018.
  4. Short-term effects of metformin and myo-inositol in women with polycystic ovarian syndrome (PCOS): a meta-analysis of randomized clinical trials.. Gynecol Endocrinol, 2019.
  5. Inositol safety: clinical evidences.. Eur Rev Med Pharmacol Sci, 2011.
  6. Effects of inositol in women with polycystic ovary syndrome: an umbrella review of meta-analyses from randomized controlled trials.. Front Endocrinol (Lausanne), 2026.
  7. Inositol for Polycystic Ovary Syndrome: A Systematic Review and Meta-analysis to Inform the 2023 Update of the International Evidence-based PCOS Guidelines.. J Clin Endocrinol Metab, 2024.
  8. Efficacy of Myo-inositol on Anthropometric, Metabolic, and Endocrine Outcomes in PCOS Patients: a Meta-analysis of Randomized Controlled Trial.. Reprod Sci, 2022.
  9. Effectiveness of inositol, metformin and their combination in women with PCOS undergoing assisted reproduction: systematic review and meta-analysis.. Gynecol Endocrinol, 2022.
  10. Effect of myo-inositol supplementation in mixed ovarian response IVF cohort: a systematic review and meta-analysis.. Front Endocrinol (Lausanne), 2025.
  11. Myo-inositol administration positively effects ovulation induction and intrauterine insemination in patients with polycystic ovary syndrome: a prospective, controlled, randomized trial.. Gynecol Endocrinol, 2017.
  12. The effectiveness of inositol and metformin on infertile polycystic ovary syndrome women with resistant to letrozole.. Arch Gynecol Obstet, 2019.
  13. Comparison of metformin with inositol versus metformin alone in women with polycystic ovary syndrome: a systematic review and meta-analysis of randomized controlled trials.. Endocrine, 2025.
  14. The Efficacy and Safety of Myo-inositol Supplementation for the Prevention of Gestational Diabetes Mellitus in Overweight and Obese Pregnant Women: A Systematic Review and Meta-Analysis.. J ASEAN Fed Endocr Soc, 2023.