Inositol is a natural sugar-like compound sold as a supplement for PCOS (now also called PMOS). Trials suggest it may improve some metabolic measures and period regularity, and myo-inositol likely causes fewer stomach side effects than metformin, but most of the evidence is low quality. The 2023 international PCOS guideline says it could be considered based on your preferences, but recommends no specific type or dose and calls it experimental for infertility. Trials commonly used 1 to 4 g of myo-inositol a day. This guide explains what the studies found, the types, study doses, side effects, how it compares with metformin, pregnancy and how to choose a product in Malaysia.
Ringkasan: Inositol untuk PCOS
- Inositol ialah sebatian semula jadi yang dijual sebagai suplemen untuk PCOS.
- Kajian menunjukkan ia mungkin membantu beberapa ukuran metabolik dan keteraturan haid, tetapi kebanyakan bukti berkualiti rendah.
- Garis panduan antarabangsa 2023: boleh dipertimbangkan mengikut pilihan anda, tetapi tiada jenis atau dos khusus yang disyorkan.
- Dos dalam kajian: myo-inositol 1 hingga 4 g sehari. Ini bukan preskripsi.
- Kesan sampingan paling biasa: perut tidak selesa.
- Jika anda hamil, menyusu atau mengambil ubat kencing manis, tanya doktor dahulu.
Sumber: International PCOS Guideline 2023; Fitz 2024; Greff 2023; WebMD.
Apa itu inositol?
Inositol is a naturally occurring sugar found in foods such as cereals, corn, legumes and meat (Cochrane 2023). Myo-inositol, the main type in supplements, is one of the messengers inside cells that carries the insulin signal (Cochrane 2023).
That is why it is studied for PCOS: insulin resistance is common in the condition, and inositol may help the body respond to insulin (Fitz 2024). Insulin resistance means the body needs more insulin to keep blood sugar normal.
You also get inositol from food. Fruits, beans, grains and nuts contain the most, and fresh produce contains more than frozen or canned (Clements 1980). Diets designed in that study provided 225 to 1,500 mg of myo-inositol a day, which is below the upper doses used in PCOS trials. We did not find trials testing a high-inositol diet for PCOS.
Kebaikan inositol: what the studies found
The largest recent review was written to inform the 2023 international PCOS guideline. It covered 30 trials with 2,230 women and concluded that the evidence is limited and inconclusive (Fitz 2024). This table shows the main results, with how confident researchers were in each.
| What you want to improve | What trials found | Certainty |
|---|---|---|
| Regular periods | More likely than with placebo (2 trials, 118 women; Greff 2023). No clear difference between myo-inositol and metformin (Fitz 2024). | Very low (placebo); moderate (metformin) |
| Insulin resistance | Myo-inositol with folic acid lowered the HOMA-IR score more than folic acid alone in 2 trials with 70 women (Fitz 2024). No significant change against placebo in another review (Greff 2023). No clear difference from metformin (Fitz 2024). | Very low to low |
| Male hormones | Lower total and free testosterone than placebo (Greff 2023). No clear difference in total testosterone between myo-inositol and metformin (Fitz 2024). | Moderate |
| Ovulation | D-chiro-inositol raised ovulation against placebo, but in only 2 small trials with 64 women. No clear difference between myo-inositol and metformin (Fitz 2024). | Low |
| Weight | BMI fell by 0.45 more than with placebo, about 1 kg for a woman 160 cm tall (Greff 2023). D-chiro-inositol trials favoured placebo for BMI (Fitz 2024). | Mixed |
| Excess hair | Metformin did better than myo-inositol (Fitz 2024). | Low |
| Acne | Adding inositol to metformin made no significant difference to acne in a review of 6 trials (Kelly 2025). We did not find strong evidence for inositol alone. | Limited |
| Pregnancy | Uncertain. See the section on pregnancy below (Cochrane 2018; Fitz 2024). | Mostly very low to low |
What the guideline says. The 2023 international PCOS guideline says inositol in any form could be considered based on your own preferences and values. It notes limited harm and possible improvement in metabolic measures, but limited clinical benefits for ovulation, excess hair and weight (Teede 2023).
Why reviews seem to disagree
You may see one review called “effective and safe” and another called “limited and inconclusive”. Both are real:
- Greff 2023 pooled 26 trials and 1,691 women. It concluded that inositol is effective and safe, and that it was not worse than metformin in most outcomes. Its authors listed small studies, mixed groups of women and different doses as limitations.
- Fitz 2024 covered 30 trials and rated most of the evidence as low or very low certainty. Its authors advise women and doctors to weigh that uncertainty together with personal values and preferences.
In practice, the findings overlap more than the headlines suggest. Inositol looks low risk in short trials and may help some measures, but no one can promise that it will fix your own symptoms.
Myo-inositol, D-chiro-inositol and the 40:1 ratio
| Type | What it is | What to know |
|---|---|---|
| Myo-inositol | The main type in most supplements and PCOS trials | Studied against folic acid, placebo and metformin (Fitz 2024) |
| D-chiro-inositol | A related form, also sold alone | Fewer trials. The placebo comparison came from 2 trials with 64 women (Fitz 2024) |
| Myo-inositol + D-chiro-inositol (40:1) | A combination often promoted as matching the body’s ratio | One trial compared 7 formulations with 8 women each and favoured 40:1 for ovulation, with weaker results when the mix held more D-chiro-inositol (Nordio 2019) |
The 40:1 trial is too small to settle the question. The international guideline says specific types, doses or combinations cannot currently be recommended in adults or teenagers with PCOS, because good evidence is lacking (Teede 2023).
Dos inositol dalam kajian
There is no official dose. These are the amounts used in trials, not a prescription:
| Form | Daily amount in trials | Source |
|---|---|---|
| Myo-inositol | 1 to 4 g, often with 200 to 400 mcg of folic acid | Fitz 2024 |
| D-chiro-inositol | 600 mg to 1.2 g | Fitz 2024 |
| Myo-inositol + D-chiro-inositol (40:1) | 550 mg + 13.8 mg, taken twice a day, in some trials | Fitz 2024 |
How long. Trials ran from about 7 weeks to 6 months (Greff 2023; Fitz 2024), so we know little about taking it for years. In one analysis, a rise in SHBG, a protein that binds testosterone, appeared only in studies lasting at least 24 weeks (Unfer 2017).
How to take it. Follow the product label or your doctor’s advice. WebMD advises taking it on an empty stomach with a full glass of water, and avoiding food for about 2 hours before and after, because it may bind minerals such as calcium, iron, magnesium and zinc.
Kesan sampingan inositol
- Stomach upset is the most common side effect (WebMD).
- Higher doses: one review found mild nausea, wind and diarrhoea only at the highest dose studied, 12 g a day (Carlomagno 2011).
- Allergic reactions can happen and may be serious (WebMD). Get urgent help if you have swelling of the face or throat, or trouble breathing.
- Unknowns: trials were mostly short. The international guideline says side effects and safety are not known when inositol is used for fertility (Teede 2023).
Who should ask a doctor or pharmacist first
- Pregnant or breastfeeding women. It is not known whether inositol could affect a pregnancy or harm a baby, or whether it passes into breast milk (WebMD).
- People taking diabetes medicine (WebMD). Ask whether you need to check your blood sugar more often.
- People taking calcium, iron, magnesium or zinc supplements (WebMD).
- People with bipolar disorder. A 1996 case report raised the question of whether inositol could trigger mania (Levine 1996). This is a single report, not proof, but speak to your psychiatrist first.
- Teenagers. The guideline does not recommend any specific type or dose for them (Teede 2023), so ask a doctor first.
Inositol vs metformin
| Inositol | Metformin | |
|---|---|---|
| What it is | Supplement | Prescription medicine |
| Guideline role | Could be considered based on your preferences | Should be considered for adults with a BMI of 25 or more, for metabolic results |
| Excess hair and waist | Less effective | Better in trials; the guideline prefers it |
| Periods, ovulation, pregnancy | No clear difference | No clear difference |
| Stomach side effects | Fewer | More, usually mild and short-lived |
Sources: Teede 2023; Fitz 2024.
The gap in side effects was large in one review: 7% with inositol against 53% with metformin across 4 trials (Greff 2023). But when Fitz 2024 looked only at the trials at low risk of bias, it found no difference in stomach side effects.
Can you take both? A review of 6 trials with 388 women found that metformin plus inositol improved period regularity and excess hair more than metformin alone, but not acne, BMI, fasting blood sugar or HOMA-IR. The authors said more studies are needed (Kelly 2025).
Do not stop a prescribed medicine on your own. The combined pill and metformin have clearer roles: the guideline says the pill could be recommended for excess hair or irregular periods, and metformin for metabolic results in women with a BMI of 25 or more (Teede 2023). Our PCOS guide covers these treatments along with diet and lifestyle.
Nak hamil dan semasa mengandung
Trying to conceive. The international guideline calls inositol, alone or with other treatments, an experimental therapy for infertility in PCOS, because its benefits and risks are too uncertain (Teede 2023). A Cochrane review of 13 trials with 1,472 women, mostly before IVF, was unsure whether myo-inositol improved live birth or pregnancy rates, and rated the evidence as low to very low quality (Cochrane 2018).
If you are having trouble getting pregnant, see a doctor rather than relying on a supplement. Our guide to cara cepat hamil explains when to get checked.
During pregnancy. A Cochrane review of 7 trials with 1,319 women found that myo-inositol may lower the risk of gestational diabetes (risk ratio 0.53). The certainty was low to very low. Six of the trials were in Italy and one in Ireland, so the results may not apply everywhere, and the reviewers asked for more studies in women of different ethnic backgrounds (Cochrane 2023). Do not start it in pregnancy without asking your doctor.
Folic acid is still needed. Many trials gave folic acid with inositol, and it does not replace the folic acid advised before and during early pregnancy.
Choosing a product in Malaysia
The international guideline warns that inositol products may be less tightly regulated than medicines, and that dose, quality and combinations can vary (Teede 2023). Before buying:
- Check for a MAL number from the National Pharmaceutical Regulatory Agency (NPRA). Our guide to checking KKM and halal status shows how.
- Read the label. It should state which type of inositol it contains and how much is in each serving. Some products need several capsules or sachets to reach the amount on the front of the pack.
- Be careful with big promises. Avoid anything claiming to cure PCOS or balance hormones quickly. Some slimming products sold in Malaysia have been found to contain banned drugs; see our guide to weight loss supplements.
- Tell your doctor you are taking it. The guideline encourages this for inositol and other complementary therapies (Teede 2023).
When to see a doctor
A supplement should not delay a proper check. See a doctor if:
- you have late or irregular periods, excess hair or persistent acne and have not been checked for PCOS;
- you are having trouble getting pregnant;
- you are pregnant, breastfeeding or taking regular medicine and want to try inositol;
- you have stomach symptoms that do not settle after starting it;
- your symptoms have not changed after the period you agreed with your doctor.
Get urgent help if you develop swelling of the face or throat, or trouble breathing, after taking it.
Frequently asked questions (FAQ)
Inositol untuk apa (what is inositol used for)?
Inositol is sold mainly for PCOS (now also called PMOS). It plays a part in how the body responds to insulin, and insulin resistance is common in PCOS, so it has been studied for periods, ovulation, hormones and blood sugar (Fitz 2024). It is a supplement, not a cure, and it is not a replacement for medicines your doctor has prescribed.
Adakah inositol berkesan untuk PCOS (does inositol work for PCOS)?
It may help some measures, but the evidence is weak. Trials suggest benefits for some metabolic measures, and one review found periods were more likely to become regular than with placebo, though that result was very low certainty (Fitz 2024; Greff 2023). The 2023 international PCOS guideline says it could be considered based on your preferences and values, while noting limited clinical benefits for ovulation, excess hair and weight.
Myo-inositol atau D-chiro-inositol, mana lebih baik (which type is better)?
No type has been shown to be clearly better. The 2023 international guideline says specific types, doses or combinations cannot currently be recommended because good evidence is lacking. Most trials used myo-inositol. The popular 40:1 ratio comes largely from small studies, including one trial with just 8 women in each group (Nordio 2019).
Berapa dos inositol untuk PCOS (what dose is used for PCOS)?
There is no officially recommended dose. Trials commonly used 1 to 4 g of myo-inositol a day, often with 200 to 400 mcg of folic acid, and 600 mg to 1.2 g a day of D-chiro-inositol (Fitz 2024). These are study doses, not a prescription. Follow the product label or your doctor’s advice.
Berapa lama baru nampak kesan inositol (how long does it take to work)?
No one can give a reliable timeline. Trials lasted from about 7 weeks to 6 months (Greff 2023; Fitz 2024). In one analysis, a rise in the hormone-binding protein SHBG was seen only in studies lasting at least 24 weeks (Unfer 2017). Agree with your doctor what you are hoping will change, and review it after a set period.
Apa kesan sampingan inositol (what are the side effects)?
An upset stomach is the most common side effect (WebMD). One review found mild nausea, wind and diarrhoea only at the highest dose studied, 12 g a day (Carlomagno 2011). Allergic reactions are possible but serious ones need urgent care. Long-term safety is not well studied, and the international guideline says side effects and safety are not known when inositol is used for fertility.
Boleh ke inositol ganti metformin (can inositol replace metformin)?
Do not swap on your own. Metformin did better than inositol for excess hair and waist-to-hip ratio, while inositol caused fewer stomach side effects (Fitz 2024). There was no clear difference for several other results, such as period regularity and ovulation. The 2023 guideline prefers metformin for excess hair and central fat. Talk to your doctor before stopping or changing any prescribed medicine.
Boleh makan inositol kalau nak hamil atau semasa mengandung (can I take it when trying to conceive or pregnant)?
Ask your doctor first. The international guideline calls inositol experimental for infertility in PCOS, because its benefits and risks are too uncertain. WebMD says it is not known whether inositol could affect a pregnancy or harm a baby. Trials in pregnancy suggest it may lower the risk of gestational diabetes, but the certainty is low to very low (Cochrane 2023). Folic acid is still needed before and during early pregnancy.
Inositol boleh kuruskan badan ke (does inositol help you lose weight)?
Do not expect much. One review found BMI fell by 0.45 more than with placebo, which is about 1 kg for a woman 160 cm tall (Greff 2023). Another found that D-chiro-inositol trials favoured placebo for BMI (Fitz 2024). The international guideline lists weight among the areas where inositol has limited clinical benefit.
Makanan apa ada inositol (which foods contain inositol)?
Fruits, beans, grains and nuts contain the most myo-inositol, and fresh produce contains more than frozen or canned (Clements 1980). The diets designed in that study provided 225 to 1,500 mg a day, which is below the upper doses used in PCOS trials. We did not find trials testing a high-inositol diet for PCOS.
Disclaimer
This article is for general information only and is not a substitute for advice, diagnosis or treatment from a doctor or pharmacist. Health supplements are not intended to diagnose, treat, cure or prevent any disease. Talk to a healthcare professional before starting, stopping or changing any supplement or medicine.
References
- Teede HJ, et al. Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. J Clin Endocrinol Metab. 2023;108(10):2447-2469.
- Fitz V, 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. J Clin Endocrinol Metab. 2024;109(6):1630-1655.
- Greff D, et al. 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;21(1):10.
- Kelly FA, et al. 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;87(2):389-399.
- Unfer V, et al. Myo-inositol effects in women with PCOS: a meta-analysis of randomized controlled trials. Endocr Connect. 2017;6(8):647-658.
- Nordio M, et al. The 40:1 myo-inositol/D-chiro-inositol plasma ratio is able to restore ovulation in PCOS patients: comparison with other ratios. Eur Rev Med Pharmacol Sci. 2019;23(12):5512-5521.
- Showell MG, et al. Inositol for subfertile women with polycystic ovary syndrome. Cochrane Database Syst Rev. 2018;12(12):CD012378.
- Motuhifonua SK, et al. Antenatal dietary supplementation with myo-inositol for preventing gestational diabetes. Cochrane Database Syst Rev. 2023;2(2):CD011507.
- Carlomagno G, Unfer V. Inositol safety: clinical evidences. Eur Rev Med Pharmacol Sci. 2011;15(8):931-936.
- Clements RS, Darnell B. Myo-inositol content of common foods: development of a high-myo-inositol diet. Am J Clin Nutr. 1980;33(9):1954-1967.
- Levine J, et al. Inositol-induced mania? Am J Psychiatry. 1996;153(6):839.
- Inositol: uses, side effects and more — WebMD
- National Pharmaceutical Regulatory Agency (NPRA), Ministry of Health Malaysia
