Metformin for PCOS: Health Benefits, Risks, and Alternatives

Updated 09 January 2023

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Reviewed by Irina Ilyich, Flo lead medical advisor, Lithuania

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Polycystic ovary syndrome (PCOS) remains one of the most common disorders of the endocrine system, affecting between 4 and 12 percent of women worldwide. Though metformin is an “off-label” treatment for PCOS, it’s still popular among people who have the condition. But is taking metformin for PCOS safe? Let’s find out.

How does metformin help PCOS treatment?

PCOS is a hormonal disorder that commonly occurs in females of reproductive or childbearing age. It can cause prolonged or infrequent periods or raised levels of androgens (the male hormones). Small follicles or cysts (fluid-filled sacs) can develop in the ovaries, which prevents the regular release of eggs (ovulation).

One of the possible factors that may play a role in developing PCOS is an excess amount of insulin in the body. Insulin helps the cells of the body use glucose, or sugar. If the body cells become insulin resistant, blood glucose levels may rise, causing more insulin to be secreted.

Metformin works as a treatment for PCOS by enhancing the body’s sensitivity to insulin. This decreases the levels of circulating insulin and also produces a positive effect on adipose (fat) tissue.

Doctors traditionally recommend metformin as a PCOS treatment for women who have a raised BMI (body mass index). However, according to the growing evidence, the response of metformin for PCOS is even better in people with a lower BMI.

The drug also appears to be effective as ovulation induction treatment in non-obese females who have anovulatory PCOS.

Metformin may also produce several other positive effects in women with PCOS such as it helps in reducing weight and their risk of developing diabetes mellitus. It also reduces levels of circulating androgen; thereby, relieving hyperandrogenic symptoms such as hirsutism and acne. Intake of metformin may also reduce the risk of developing ovarian hyperstimulation syndrome in females with PCOS who are undergoing IVF (in vitro fertilization).

Is metformin safe? Potential side effects to consider

Metformin is a relatively safe drug for PCOS. The main adverse effects that may occur while taking metformin for PCOS include various gastrointestinal symptoms. Some of these symptoms are nausea, flatulence, diarrhea, bloating, metallic taste, abdominal pain, and anorexia. Metformin may also result in malabsorption of vitamin B12 in your small intestine. In rare cases, particularly in diabetic patients, lactic acidosis may occur.

Metformin is a relatively safe drug for PCOS. The main adverse effects that may occur while taking metformin for PCOS include various gastrointestinal symptoms.

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The severity of the side effects varies from patient to patient, but in the majority of cases, symptoms get better on their own. It’s possible to begin taking metformin for PCOS gradually to reduce the severity of the adverse effects and increase the dose according to the severity of your symptoms.

The use of metformin for PCOS is contraindicated if you have any of the following conditions:

• Kidney dysfunction
• Hypersensitivity to the drug (metformin)
• Congestive heart failure
• Impaired liver function
• Chronic or acute metabolic acidosis

Metformin alternatives: other ways to treat PCOS

The main focus of treating PCOS is to manage symptoms such as hirsutism, infertility, obesity, and acne. Specific treatment may involve taking medication such as metformin or making lifestyle changes.

Lifestyle changes: Making lifestyle changes is the primary treatment modality recommended by doctors and may include losing excess weight through diet and exercise. Even losing just five percent of total body weight can help improve the condition. Weight loss may also make medicine more effective and improve menstrual regularity. 

Making lifestyle changes is the primary PCOS treatment modality recommended by doctors.

Weight loss may help in reducing the levels of androgens and insulin and in restoring ovulation. A diet rich in carbohydrates and low in fat may increase your insulin levels. There are specific diets recommended for people with PCOS. A doctor or nutritionist can advise you on which is best for you.

Medication: To regulate the menstrual cycle, your doctor may recommend the following medicines:

• Birth control pills that contain both progestin and estrogen help in decreasing the production of androgen and regulating estrogen. Regulating the hormones may help in reducing your risk of developing endometrial cancer and treating excess growth of hair, acne, and abnormal bleeding.
• Consuming progestin for a duration of 10 to 14 days every one or two months may help in regulating your menses and in protecting from endometrial cancer.
• Your doctor may prescribe metformin for PCOS to induce ovulation, but they usually prescribe clomiphene, which is an oral anti-estrogen medicine that is consumed during the first phase of the menstrual cycle.

These are some other metformin alternatives:

• Letrozole: This is a treatment for breast cancer and may help in stimulating the ovaries.
• Gonadotropins: These hormonal medicines are injected into the body.
• IVF and laparoscopic ovarian drilling may also be done as an alternative to metformin.

To decrease the excessive growth of hair, your doctor may recommend:

• Spironolactone: This medicine may block the effect of androgens on your skin. It can cause birth defects; hence, you shouldn’t take it if you are planning a pregnancy or already pregnant.
• Eflornithine: This cream may help in reducing the growth of facial hair in women.

On a final note

Metformin for PCOS is generally recommended for decreasing weight and also reducing the risk of developing gestational diabetes mellitus. It may also be effective in treating anovulatory infertility in non-obese people with PCOS.

People with PCOS who are undergoing IVF may take metformin to reduce their risk of developing ovarian hyperstimulation syndrome.

Consult your physician to determine your best options for managing PCOS.

Metformin may be an alternative to birth control pills for relieving hyperandrogenic symptoms of PCOS, such as acne and hirsutism. Consult your physician to determine your best options for managing PCOS.

If you have PCOS, you can safely take metformin under the supervision of your doctor. An oral medicine to treat type 2 diabetes, metformin helps reduce insulin levels and improves insulin resistance. Your doctor may prescribe metformin for PCOS if you don’t conceive while taking clomiphene. It also helps in losing weight and slowing the progression of prediabetes to type 2 diabetes.

History of updates

Current version (09 January 2023)

Reviewed by Irina Ilyich, Flo lead medical advisor, Lithuania

Published (04 November 2019)