§.01What inositol does in the body.
Inositol is a sugar alcohol that acts as a secondary messenger in cellular signaling. Two stereoisomers matter clinically:
- Myo-inositol (MI): insulin signaling, ovarian function, neurotransmitter modulation.
- D-chiro-inositol (DCI): a derivative of MI, more involved in glycogen synthesis. Smaller body pool.
The body normally maintains MI:DCI at roughly 40:1. In PCOS and insulin resistance, this ratio is often disturbed. The trial-supported PCOS supplementation protocol restores the 40:1 ratio externally (Unfer et al., 2017).
§.02PCOS: the trial-supported protocol.
The most consistent human trial evidence for inositol is in polycystic ovary syndrome (PCOS) with insulin resistance:
- Dose: 4 grams myo-inositol + 100 mg d-chiro-inositol per day (the 40:1 ratio).
- Split: 2 grams MI + 50 mg DCI twice daily, morning and evening.
- Duration: 12 to 16 weeks for first results; many protocols continue 6+ months.
- Outcomes documented: improved insulin sensitivity, more regular menstrual cycles, reduced androgen levels, modest improvements in ovulation and fertility outcomes.
Effect sizes are modest but clinically meaningful for many women with PCOS-related insulin resistance, and the safety profile is excellent.
§.03Panic disorder: a different (higher) dose.
The other reasonably-evidenced use case is panic disorder, where the trial protocol uses 12 to 18 grams of myo-inositol daily — substantially higher than the PCOS protocol (Benjamin et al., 1995, replicated since).
At this dose, effects on panic frequency and severity have been comparable to fluvoxamine in head-to-head small trials. This is not a self-supplementation protocol. If panic disorder is your goal, work with a psychiatrist; the high doses, the duration, and the integration with any prescription anxiety treatment require supervision.
§.04What inositol is NOT documented for.
- Generalized anxiety at PCOS doses. The panic-disorder evidence at high doses does not extend to "anxious mood" in general.
- Depression. Small mixed trials; no consistent positive signal.
- Weight loss beyond what improved insulin sensitivity provides in PCOS.
- Sleep. Some users report drowsiness at high doses; not a primary sleep aid.
- Fertility in non-PCOS women. The PCOS-specific mechanism does not generalize.
§.05Side effects and interactions.
Inositol is one of the better-tolerated supplements:
- Mild GI discomfort (nausea, loose stools) at doses above 6 grams per day. Split dosing reduces this.
- Possible mild hypoglycemia in adults on insulin or sulfonylureas (because it improves insulin sensitivity). Monitor blood sugar if you are on these medications.
- Pregnancy: increasingly used in PCOS during pregnancy under clinician guidance; otherwise default to coordinating with your OB.
- Lithium: theoretical interaction (lithium and inositol both affect the same signaling pathway). Avoid combining without psychiatric oversight.
§.99The bottom line.
For PCOS-related insulin resistance, the trial-supported protocol is 4 grams of myo-inositol + 100 mg of d-chiro-inositol per day (the 40:1 ratio) for 12 to 16 weeks. For panic disorder, the dose is higher (12 to 18 grams of myo-inositol daily) and should be supervised. For general "anxiety" or "mood support," the evidence is thin. PuraVigor sells the PCOS-protocol formulation; if you have panic disorder, work with a psychiatrist on the supervised protocol.
Inositol 4g (myo + d-chiro 40:1) — at the apothecary.
Reviewed by Dr. Marthe Janssen, PharmD. Last updated May 19, 2026.
Disclaimer: this article is educational and does not substitute for advice from your prescriber. Statements have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease.