Recommended Dosage of Myo- and D-Chiro-Inositol for PCOS
What's the right inositol dosage for PCOS? This guide covers the standard 2,000-4,000mg daily dose, the 40:1 ratio, and safety considerations for effective hormonal balance.
Clear, evidence-based dosing ranges for MI, DCI, and the 40:1 combo used in PCOS trials.
Key takeaways
- Most trials use myo-inositol 2 g twice daily; often with 200 µg folic acid twice daily.
- MI+DCI in a 40:1 ratio is widely studied; a common daily total is 4,000 mg MI + 100 mg DCI.
- High DCI dosing may impair ovarian parameters in PCOS; use combinations studied in trials.
Information is educational. Consult your clinician before starting supplements.
Evidence-based dosage at a glance
Study-style regimens and outcomes
| Regimen (per day) | Typical schedule | Setting/outcome highlights | Evidence strength |
|---|---|---|---|
| MI 4 g + folic acid 400 µg | 2 g MI + 200 µg folate, BID | Ovulation restored in large cohort; improved IVF parameters | ✔ Human studies (observational + RCT adjuncts) |
| MI+DCI 40:1 (≈ MI 4 g + DCI 100 mg) | Split doses BID | Better ovulation vs other ratios; hormonal and metabolic gains | ✔ RCTs and comparative studies |
| DCI alone (varied) | Varies | Mixed; high doses linked to worse ovarian markers in PCOS | ⚠ Narrative + animal + small human data |
If you’re researching basics first, start with an overview like PCOS supplements.
Myo-inositol alone: what trials actually used
Typical study dose
Most studies assessing menstrual regularity, ovulation, and metabolic markers use MI 2 g BID, frequently combined with folic acid 200 µg BID over ~10–12 weeks.
What it affects
Reports include restored ovulation, improved testosterone and progesterone profiles, and better IVF embryo quality when MI is used before stimulation.
Who it suits
General PCOS populations, including those pursuing IVF, appear to benefit.
Trials are heterogeneous. Individual response varies; medical guidance is advisable.
Myo + D-Chiro together: why the 40:1 ratio
Key points
- Physiologic 40:1 MI:DCI performs best for ovulation vs other ratios.
- Practical daily total used: MI 4,000 mg + DCI 100 mg, split BID.
What the ratio means
Comparative data suggest the 40:1 MI:DCI combination restores ovulation more reliably than mixes tilted toward DCI. Altering the ratio in favor of DCI reduces efficacy.
Outcomes to expect
Studies report improved ovulation and pregnancy rates and favorable hormonal and metabolic profiles with 40:1, including recent clinical data in phenotype-A PCOS.
How people take it
A common pattern is 2 g MI + 50 mg DCI twice daily (total 4 g MI + 100 mg DCI/day), often before meals.
Avoid high-DCI formulas unless specifically indicated by a clinician. See cautions below and PCOS basics.
D-Chiro-inositol alone: limits and cautions
Why caution exists
Narrative and experimental work indicates elevated DCI can increase androgens and down-regulate aromatase, undermining ovarian function in PCOS. Balance with MI seems key.
Counter-signals
Small ICSI studies report improved oocyte cytoplasm with higher DCI mixes, yet sample sizes are limited and not generalizable to all PCOS. Clinicians often prefer the 40:1 MI-DCI approach for ovulatory goals.
If you are already on metformin or fertility meds, coordinate dosing with your specialist. See PCOS treatment options.
How to take it: timing, duration, and formulation
Timing
Consumer medical resources advise taking inositols just before a meal for absorption; trials typically split doses morning/evening.
Duration
In a large cohort, mean use was ~10 weeks; many protocols reassess after 3 months and continue if responding.
Form matters
Powders allow precise MI:DCI ratios; combo products should disclose exact milligrams and ratio. Target 40:1 unless your clinician specifies otherwise.
Keep a simple log of cycle changes, ovulation tests, and any side effects to discuss at follow-up.
References
- Regidor PA et al. Horm Mol Biol Clin Investig. 2018. PMID: 29498933.
- Nordio M et al. Eur Rev Med Pharmacol Sci. 2019. “40:1 ratio…”
- Benelli E et al. Int J Endocrinol. 2016. Combined MI+DCI.
- Monastra G et al. Front Endocrinol. 2021. PCOS and inositols clarifications.
- Verywell Health. Updated Mar 28, 2025. Consumer dosing overview.
Frequently Asked Questions
4 g/day, usually 2 g twice daily, often with folic acid 200 µg twice daily.
A practical, studied target is MI 4,000 mg + DCI 100 mg per day (40:1), split into two doses.
Trials often report changes by 8–12 weeks. Track cycles and labs with your clinician.
Avoid high-dose DCI in PCOS unless directed; data link it to reduced aromatase and worse oocyte parameters.
Consumer guidance favors before meals; keep dosing consistent daily.
