Inositol
In PCOS, pooled trials found regular cycles and ovulation more often on inositol than placebo, and a guideline review called the evidence limited. Pooled pregnancy trials found less gestational diabetes, though a 464-woman PCOS trial found no drop in complications. Depression and anxiety did not change. In infants born before 28 weeks, a trial stopped early for higher mortality.
Add to Bio HackChecked 2026-11-09
- Status
- Dietary supplement in the US.
- Also called
- myo-inositol, D-chiro-inositol, DCI, MI, myo-inositol with D-chiro-inositol 40:1, vitamin B8, inositol hexaphosphate, IP6
- Taken for
- PCOS, irregular periods, ovulation, fertility, insulin resistance, gestational diabetes, weight loss, anxiety, panic attacks, depression, PMDD, OCD
Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on
Shown to help4
- StrongShown to lower gestational diabetes about 44% to 47% with myo-inositol in pregnant women. One trial in women with PCOS found no change in a combined outcome.
- ModerateShown to make a regular cycle about 1.8 times as likely as placebo in women with PCOS. The guideline review called the evidence limited.
- ModerateShown to lower free and total testosterone and glucose and raise SHBG in women with PCOS. Metformin did better on hirsutism.
- ModerateShown to lower BMI slightly, about 0.6 kg/m², and glucose, triglycerides and blood pressure in adults across several conditions, at low certainty for some.
Reported risks2
What people take it for, and what was found
Shown to help4
Menstrual cycles and ovulation in PCOS
Shown to make a regular cycle about 1.8 times as likely as placebo in women with PCOS. The guideline review called the evidence limited.
The numbers and sources
- Effect
- A regular cycle was 1.79 times as likely on inositol as on placebo (95% CI 1.13 to 2.85), and results did not differ from metformin [1]. In an earlier analysis, ovulation rate (RR 2.3, 95% CI 1.1 to 4.7) and cycle frequency (RR 6.8, 95% CI 2.8 to 16.6) were higher than placebo [2]. A review for the 2023 international PCOS guideline found possible ovulation benefits for D-chiro-inositol and called the overall evidence limited and inconclusive [3].
- Population
- 1,691 women in 26 trials [1]; 601 women in 10 trials [2]; 2,230 women in 30 trials [3].
- Sources
- [1], [2], [3]
- Caveats
- Sources disagree on certainty. Pregnancy rates came from single trials, and no trial reported live births or miscarriage [2]. Ovulation heterogeneity was high (I² 75%) [2].
Hormones and blood sugar in PCOS
Shown to lower free and total testosterone and glucose and raise SHBG in women with PCOS. Metformin did better on hirsutism.
The numbers and sources
- Effect
- Against placebo, inositol lowered BMI (MD -0.45), free testosterone (MD -0.41), total testosterone (MD -20.4) and glucose (MD -3.14), and raised sex-hormone-binding globulin (MD 32.1) [1]. The guideline review found benefits for some metabolic measures and none for others. Metformin did better on waist-hip ratio and hirsutism [3].
- Population
- 1,691 women in 26 trials [1]; 2,230 women in 30 trials [3].
- Sources
- [1], [3]
- Caveats
- Units are as reported in the abstract. The guideline review rated BMI evidence very uncertain [3].
Gestational diabetes prevention
Shown to lower gestational diabetes about 44% to 47% with myo-inositol in pregnant women. One trial in women with PCOS found no change in a combined outcome.
The numbers and sources
- Effect
- Myo-inositol lowered gestational diabetes (RR 0.53, 95% CI 0.31 to 0.90), hypertensive disorders of pregnancy (RR 0.34, 95% CI 0.19 to 0.61) and preterm birth (RR 0.35, 95% CI 0.17 to 0.70). Cesarean section did not differ [4]. A 2026 meta-analysis of 12 RCTs (4,765 women) found a 44% lower risk of gestational diabetes, with no significant difference in hypertensive disorders, cesarean delivery, macrosomia, preterm birth or newborn low blood sugar [5]. In one Italian trial in overweight women, gestational diabetes occurred in 11.6% on myo-inositol and 27.4% on placebo (OR 0.33, 95% CI 0.15 to 0.70) [6]. In a Dutch trial in pregnant women with PCOS, 2 g of myo-inositol twice a day did not lower a composite of gestational diabetes, preeclampsia or preterm birth (25.0% against 26.8%, RR 0.93, 95% CI 0.68 to 1.28) [7].
- Population
- 1,319 women in 7 trials, 6 in Italy and 1 in Ireland [4]; 4,765 pregnant women or women planning pregnancy, without diabetes, in 12 RCTs [5]; 220 overweight, non-obese pregnant women [6]; 464 pregnant women with PCOS at 13 hospitals [7].
- Sources
- [4], [5], [6], [7]
- Caveats
- The Cochrane authors rated the evidence low to very low certainty. No trial reported perinatal death [4]. The two reviews agree on gestational diabetes and differ on high blood pressure and preterm birth [4][5]. The overweight trial was open-label [6]. The PCOS trial reported a composite outcome, and the abstract does not give gestational diabetes alone [7].
Weight, blood sugar and lipids
Shown to lower BMI slightly, about 0.6 kg/m², and glucose, triglycerides and blood pressure in adults across several conditions, at low certainty for some.
The numbers and sources
- Effect
- In 18 RCTs (898 participants) of at least 4 weeks, inositol lowered BMI by 0.57 kg/m² (95% CI -1.10 to -0.03), waist circumference by 2.36 cm, glucose by 7.25 mg/dL, HOMA-IR by 1.21, triglycerides by 29.80 mg/dL, LDL cholesterol by 5.15 mg/dL, and systolic and diastolic pressure by 5.34 and 6.12 mm Hg [11].
- Population
- Adults in RCTs across several conditions [11].
- Sources
- [11]
- Caveats
- Certainty was low to very low for BMI, waist and blood pressure, and moderate for glucose, insulin and HOMA-IR. Heterogeneity was high for most outcomes, and the authors note a high risk of bias in the trials [11].
Mixed results1
Fertility treatment in PCOS
Mixed results: one review found higher clinical pregnancy rates in women with PCOS in fertility treatment, and a larger review found no effect.
The numbers and sources
- Effect
- In 17 intervention studies of women with PCOS undergoing assisted reproduction, myo-inositol or D-chiro-inositol raised the clinical pregnancy rate (RR 1.64, 95% CI 1.25 to 2.15) and top-grade embryos (RR 1.12), and lowered antral follicle count and anti-Mullerian hormone [8]. In 11 studies (981 women undergoing IVF), myo-inositol raised the mature (MII) oocyte rate (OR 1.55, 95% CI 1.04 to 2.31) and the fertilization rate (OR 1.62, 95% CI 1.21 to 2.16). The MII oocyte rate did not rise in poor responders [9]. A 2026 meta-analysis of 39 studies found fewer irregular periods on myo-inositol (RR 0.78, 95% CI 0.68 to 0.89) and no significant effect on clinical pregnancy rate [10].
- Population
- Women with PCOS in assisted reproduction [8][10]. Women undergoing IVF, with and without PCOS [9].
- Sources
- [8], [9], [10]
- Caveats
- The reviews disagree on clinical pregnancy [8][10]. None of the abstracts reports live births for inositol. Heterogeneity was high for several outcomes [8][10].
Not shown to help1
Depression and anxiety
Not shown to change depression, anxiety or obsessive-compulsive symptoms. One small trial found fewer panic attacks on 12 g a day.
The numbers and sources
- Effect
- Inositol did not significantly change depressive, anxiety or obsessive-compulsive symptoms against placebo. Responders in depression were marginally more common (P = 0.06) [12]. In a 4-week crossover trial, panic attack frequency and severity fell more on 12 g a day than placebo [13].
- Population
- 242 people in 7 depression trials and 70 in 4 anxiety trials [12]; 21 people with panic disorder [13].
- Sources
- [12], [13]
- Caveats
- Trials were few and small [12]. The panic trial is one of four pooled anxiety trials [12][13].
Doses studied
The overweight pregnancy trial used 2 g of myo-inositol twice a day [6], as did the PCOS pregnancy trial, with 0.2 mg of folic acid [7]. The panic disorder trial used 12 g a day [13]. The preterm infant trial gave 40 mg per kg every 12 hours, first IV and then by mouth, for up to 10 weeks [14].
Risks
Reported risks2
Death in extremely preterm infants
One trial, stopped early, found more deaths in extremely preterm infants given myo-inositol, 18% against 11% on placebo.
The numbers and sources
- How common
- Very common: more than 1 in 10 people.
- Effect
- The trial stopped early. Death or severe retinopathy of prematurity occurred in 29% on myo-inositol and 21% on placebo (adjusted RR 1.41, 95% CI 1.08 to 1.83). Death before 55 weeks' postmenstrual age occurred in 18% and 11% (adjusted RR 1.66, 95% CI 1.14 to 2.43) [14].
- Population
- 638 infants born before 28 weeks' gestation at 18 US neonatal centers [14].
- Sources
- [14]
- Caveats
- One trial, stopped early. It used IV and enteral doses in newborns, not adult supplements [14].
Stomach side effects
Gut upset was slightly more common than on placebo in mood disorder trials, and less common than on metformin in PCOS.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- Gastrointestinal upset was marginally more common on inositol than placebo (P = 0.06) [12]. Against metformin, myo-inositol likely caused fewer gastrointestinal adverse events [3].
- Population
- 11 trials in mood and anxiety disorders [12]; 30 trials in PCOS [3].
- Sources
- [3], [12]
- Caveats
- The guideline review describes the events as typically mild and self-limited [3].
Claims tested and not found
Sources
- Greff D, Juhász AE, Váncsa S, et al. Inositol is an effective and safe treatment in polycystic ovary syndrome: a systematic review and meta-analysis of randomized controlled trials. Reproductive Biology and Endocrinology. 2023. https://doi.org/10.1186/s12958-023-01055-z
- Pundir J, Psaroudakis D, Savnur P, et al. Inositol treatment of anovulation in women with polycystic ovary syndrome: a meta-analysis of randomised trials. BJOG. 2018. https://doi.org/10.1111/1471-0528.14754
- Fitz V, Graca S, Mahalingaiah S, et al. Inositol for Polycystic Ovary Syndrome: A Systematic Review and Meta-analysis to Inform the 2023 Update of the International Evidence-based PCOS Guidelines. The Journal of Clinical Endocrinology & Metabolism. 2024. https://doi.org/10.1210/clinem/dgad762
- Motuhifonua SK, Lin L, Alsweiler J, et al. Antenatal dietary supplementation with myo-inositol for preventing gestational diabetes. Cochrane Database of Systematic Reviews. 2023. https://doi.org/10.1002/14651858.CD011507.pub3
- Poyatos-León R, Martínez-Vizcaíno V, Sequí-Domínguez I, et al. The effect of myo-inositol supplementation on gestational diabetes mellitus prevention: a systematic review and meta-analysis. American Journal of Obstetrics and Gynecology. 2026. https://doi.org/10.1016/j.ajog.2026.05.020
- Santamaria A, Di Benedetto A, Petrella E, et al. Myo-inositol may prevent gestational diabetes onset in overweight women: a randomized, controlled trial. The Journal of Maternal-Fetal & Neonatal Medicine. 2016. https://doi.org/10.3109/14767058.2015.1121478
- van der Wel AWT, Frank CMC, Bout-Rebel R, et al. Myo-inositol Supplementation to Prevent Pregnancy Complications in Polycystic Ovary Syndrome: A Randomized Clinical Trial. JAMA. 2025. https://doi.org/10.1001/jama.2025.13668
- Sene AA, Saeedzarandi M, Yazdizadeh M, et al. The effect of myo-inositol on assisted reproductive technology outcomes in women with polycystic ovarian syndrome: A systematic review and meta-analysis of randomized clinical trial studies. International Journal of Reproductive BioMedicine. 2025. https://doi.org/10.18502/ijrm.v23i5.19260
- Zhang J, Zhang H, Zhou W, et al. Effect of myo-inositol supplementation in mixed ovarian response IVF cohort: a systematic review and meta-analysis. Frontiers in Endocrinology. 2025. https://doi.org/10.3389/fendo.2025.1520362
- Zia MT, Barkat-Ullah Z, Aqueel M, et al. Enhancing fertility outcomes in PMOS: The impact of metformin and myo-inositol on assisted reproductive technology success, a systematic review and meta-analysis. Journal of Gynecology Obstetrics and Human Reproduction. 2026. https://doi.org/10.1016/j.jogoh.2026.103295
- Delavar MA, Mirabi P, Rosenkranz SK, et al. Inositol supplementation efficacy in improving key cardiometabolic and anthropometric indices: a GRADE-assessed systematic review and meta-analysis of randomized controlled trials. Diabetology & Metabolic Syndrome. 2025. https://doi.org/10.1186/s13098-025-01980-6
- Mukai T, Kishi T, Matsuda Y, et al. A meta-analysis of inositol for depression and anxiety disorders. Human Psychopharmacology. 2014. https://doi.org/10.1002/hup.2369
- Benjamin J, Levine J, Fux M, et al. Double-blind, placebo-controlled, crossover trial of inositol treatment for panic disorder. American Journal of Psychiatry. 1995. https://doi.org/10.1176/ajp.152.7.1084
- Phelps DL, Watterberg KL, Nolen TL, et al. Effects of Myo-inositol on Type 1 Retinopathy of Prematurity Among Preterm Infants <28 Weeks' Gestational Age: A Randomized Clinical Trial. JAMA. 2018. https://doi.org/10.1001/jama.2018.14996