How much inositol per day should I take?

November 16, 2025 •

4 min read

While the average dietary intake of inositol is around 1 gram per day from foods like fruits, nuts, and grains, supplemental amounts are often much higher and depend entirely on the health condition being addressed. Knowing how much inositol per day should I take is crucial for potentially maximizing benefits and minimizing possible side effects.

Quick Summary

This article explains how to determine the appropriate inositol amount for specific health conditions, including PCOS, anxiety, and metabolic syndrome. It details the common amounts used in studies for myo-inositol and d-chiro-inositol, safety considerations, and how to start supplementing.

Key Points

Amount Varies Greatly: The right amount of inositol depends on the specific health condition, with amounts ranging from 2 to 18 grams daily used in studies.
Mental Health Considerations: For conditions like anxiety, OCD, and depression, research suggests higher amounts (12–18g of myo-inositol) are typically considered, but with caution.
PCOS Amounts: A common amount for polycystic ovary syndrome is 2–4 grams of myo-inositol per day, often paired with folic acid.
Mind the Myo-Inositol/D-Chiro Ratio: For PCOS, a physiological ratio of 40:1 myo-inositol to D-chiro-inositol has shown promising results in some studies.
Start Low and Monitor: It is generally recommended to begin with a low amount and gradually increase it, especially with higher amounts, to potentially minimize side effects like nausea and gas.
Consult a Doctor: Always talk to a healthcare professional before taking inositol, especially for higher amounts, during pregnancy, or if you have pre-existing conditions like diabetes or bipolar disorder.

Understanding Inositol: The Basics

Inositol, often called vitamin B8, is not a true vitamin but a sugar-like compound with a crucial role in the body's cellular functions. It helps provide structure to cell membranes and is involved in modulating insulin and key neurotransmitters like serotonin and dopamine. In supplement form, the two most common types are myo-inositol (MI) and D-chiro-inositol (DCI). While the body produces inositol naturally and it is found in many foods, supplemental intake is often considered when addressing specific conditions.

The Importance of Appropriate Amount

There is no single recommended daily allowance (RDA) for inositol, as the optimal amount is highly dependent on the condition being considered. Inadequate amounts may render the supplement ineffective, while excessively high amounts, particularly above 12 grams daily, can increase the risk of mild side effects such as nausea, gas, and stomach discomfort. Therefore, it is critical to consult a healthcare provider and start with a lower amount to assess tolerance, especially for higher regimens.

Condition-Specific Inositol Amounts

Recommended daily amounts of inositol vary significantly based on the health goal. The following figures are based on clinical research and are general information, not a substitute for professional medical advice.

Polycystic Ovary Syndrome (PCOS)

PCOS is one of the most widely studied conditions for inositol supplementation. Research supports a daily amount of myo-inositol, often combined with folic acid, to potentially improve insulin sensitivity, regulate menstrual cycles, and support fertility. A specific ratio of myo-inositol to D-chiro-inositol, typically 40:1, has been shown to be particularly considered in improving ovarian function and metabolic markers in women with PCOS. This amount is commonly split into two daily administrations.

Mental Health Conditions (Anxiety, Depression, OCD)

For mental health applications such as panic disorder, depression, and obsessive-compulsive disorder (OCD), significantly higher amounts are sometimes used compared to PCOS. Studies have shown potential benefits with a daily amount of myo-inositol. Due to the higher amount, this is typically taken in divided administrations throughout the day to minimize gastrointestinal discomfort. It is vital to increase the amount gradually and be supervised by a healthcare provider, especially for individuals with bipolar disorder, as higher amounts may trigger manic episodes.

Metabolic Syndrome and Insulin Resistance

Inositol has demonstrated efficacy in potentially improving insulin sensitivity and controlling metabolic syndrome risk factors, including high triglycerides, cholesterol, blood pressure, and blood sugar. An amount of myo-inositol twice daily for one year has been shown to potentially improve these markers in clinical studies. For managing type 2 diabetes, research suggests a daily amount of D-chiro-inositol with 400 mcg of folic acid over six months.

Other Uses: Gestational Diabetes and Fertility

Inositol has also been studied for its potential to prevent gestational diabetes during pregnancy. A combination of myo-inositol and 400 mcg of folic acid twice daily has shown promise in reducing the incidence of this condition in at-risk women. For general fertility support outside of PCOS, amounts often align with the amounts used for PCOS, focusing on potentially improving egg quality and regulating ovulation.

Comparison of Amounts for Different Conditions


Condition	Form of Inositol	Typical Daily Amount Used in Studies	Duration	Common Administration
PCOS	Myo-inositol (MI), often with D-chiro-inositol (DCI) in a 40:1 ratio	2–4 grams of MI (split)	6+ months	Divided administrations (e.g., twice daily)
Mental Health (Anxiety, OCD)	Myo-inositol (MI)	12–18 grams	4–6 weeks for studies	Divided administrations (2–3 times daily)
Metabolic Syndrome	Myo-inositol (MI)	2 grams twice daily	1 year	Twice daily
Gestational Diabetes	Myo-inositol (MI) + Folic Acid	2 grams of MI twice daily	Throughout pregnancy	Twice daily

Potential Side Effects and Safety Considerations

Inositol is generally well-tolerated, with side effects primarily linked to high amounts (over 12 grams daily). Mild gastrointestinal issues like nausea, diarrhea, and gas are the most common. Other less frequent side effects can include fatigue and dizziness. Given inositol's potential effect on blood sugar, individuals with diabetes should monitor their levels closely when considering supplementation. Those with bipolar disorder should only consider inositol under strict medical supervision due to the potential risk of triggering manic episodes. The long-term safety of high-amount inositol is not yet fully established, as most studies have been relatively short.

For more detailed scientific data on the efficacy and mechanisms of inositols, consult academic databases such as PubMed Central.

Conclusion: Finding the Appropriate Amount for You

Determining the appropriate inositol amount is not a one-size-fits-all process. It requires a clear understanding of the specific health condition you are targeting. For hormonal and metabolic issues like PCOS and metabolic syndrome, lower to moderate daily amounts are common and well-researched. For mental health concerns, much higher amounts of myo-inositol have been studied, though these require a more cautious approach and medical guidance. Given the variable nature of individual responses and the potential for drug interactions, it is always recommended to consult with a qualified healthcare provider before beginning any new supplement regimen. By considering the amount based on your needs and paying attention to your body's response, you can potentially use inositol safely and effectively.

Frequently Asked Questions

For PCOS, amounts of myo-inositol used in studies are typically around 4 grams (4,000 mg) per day, often split into two administrations. It is frequently combined with folic acid.

While some lower amounts are used, clinical studies on anxiety disorders like panic disorder have explored higher amounts, typically 12–18 grams of myo-inositol per day, under medical supervision.

Studies on metabolic syndrome have used an amount of 2 grams of myo-inositol taken twice daily for one year to potentially help with insulin sensitivity, blood pressure, and cholesterol levels.

Side effects are typically mild and not common, especially at lower amounts. At amounts over 12 grams per day, some people may experience gastrointestinal issues like nausea, gas, and diarrhea.

The time it might take to see effects varies by condition. Some studies on mental health and PCOS suggest potential benefits appearing within 4–6 weeks, but longer use (3–6 months or more) is often considered for more significant results.

Inositol may be possibly safe for short-term use during pregnancy under a doctor's supervision. Amounts up to 4,000 mg of myo-inositol have been used in studies without apparent adverse effects, often combined with folic acid to potentially help prevent gestational diabetes.

The form often considered depends on the condition. For PCOS, a combination of myo-inositol and D-chiro-inositol in a 40:1 ratio is often recommended in studies. For mental health, myo-inositol is a more commonly studied form.