Metformin for PCOS: How Does It Work?

What is Polycystic Ovary Syndrome (PCOS)?

Polycystic ovary syndrome (PCOS) affects about 8% to 13% of women, yet it often goes undiagnosed for years. This is largely because its symptoms vary from person to person and often overlap with other hormonal and metabolic conditions. And unfortunately, PCOS is also very misunderstood among the general public and even some physicians.

This condition is characterized by:

• Irregular or absent menstrual cycles
• Elevated androgen levels (such as testosterone)
• Polycystic ovarian morphology (multiple small follicles on ultrasound)

Not every woman with PCOS will have all three of these features, which is partially why getting a diagnosis can be difficult.

However, some research indicates that insulin resistance may contribute to or worsen PCOS. In fact, many women with PCOS experience insulin resistance, meaning their bodies don’t respond to insulin as efficiently as they should. This can lead to increased insulin levels, which, in turn, can worsen hormonal imbalances (including increased androgen production) and increase the risk of developing type 2 diabetes. As a result, weight gain, difficulty losing weight, infertility, acne, and excess hair growth (hirutism) are commonly associated with PCOS.

As such, your healthcare provider may focus on improving the body’s response to insulin. And metformin sometimes comes up in this context. 

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Benefits of Metformin for PCOS

Metformin was originally developed as a treatment for type 2 diabetes. However, clinicians noticed it could also benefit women with PCOS, particularly those dealing with insulin resistance. 

Today, it’s one of the more commonly prescribed medications for PCOS, even though it’s not specifically FDA-approved for this indication.

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Blood Sugar & Insulin Regulation

Metformin primarily works by improving how the body responds to insulin. It helps reduce the amount of glucose the liver produces and allows your cells to use insulin more effectively. In women with PCOS, this may lead to lower circulating insulin levels, which are closely linked to hormonal regulation.

Additionally, some studies suggest that metformin may reduce fasting insulin levels in some women with PCOS. Lower insulin levels are often associated with reduced androgen levels, which may be linked to improvements in symptoms such as irregular periods, acne, or excess hair growth. Yet, these associations don’t mean metformin will improve symptoms for every individual.

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Weight Management

Metformin is not FDA-approved for weight loss. However, some research suggests it may be associated with modest changes in body weight in women with PCOS. Larger clinical trials have shown mixed results, and metformin is generally considered more effective when used alongside lifestyle measures such as balanced nutrition and regular physical activity.

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Diabetes Risk

Insulin resistance is common in PCOS and is associated with an increased risk of developing type 2 diabetes. By improving insulin sensitivity, metformin may help support blood sugar control in some individuals. It’s also sometimes prescribed for individuals with PCOS and prediabetes to potentially delay it from developing into type 2 diabetes.

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How to Use Metformin for PCOS

Metformin is a prescription medication, meaning a licensed healthcare provider must determine if it’s appropriate for you. It’s worth noting that while metformin is FDA-approved for treating type 2 diabetes, it’s not specifically approved for PCOS. With that said, off-label use, particularly for PCOS, is common and well-documented.

Dosing depends on various individual factors, yet metformin is often started at a low dose, such as 500 mg once daily, and gradually increased over several weeks if needed. This gradual increase may help reduce gastrointestinal side effects, which are common when starting metformin.

In some cases, metformin may be used alongside other treatments. For women trying to conceive, it’s sometimes combined with ovulation-inducing medications such as clomiphene citrate. Research suggests that this combination may improve ovulation rates in some individuals, though outcomes can vary.

If pregnancy occurs, many healthcare providers recommend reassessing whether to continue metformin, as it isn’t FDA-approved for use during pregnancy. Evidence on continuing metformin in pregnancy varies by individual and clinical context, and decisions about continuing or stopping the medication should always be made by a licensed healthcare provider.

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Side Effects

Common metformin side effects include:

• Nausea
• Diarrhea
• Bloating
• Stomach discomfort

These are especially common when starting the medication or increasing your dose. 

More serious side effects are rare but can include lactic acidosis, a potentially dangerous buildup of lactic acid in the blood. However, this risk is generally higher for individuals with kidney or liver problems.

Thus, metformin is not recommended for those with significant kidney impairment, liver disease, or a history of lactic acidosis. If you have any underlying health conditions or are taking any other medications, these are important aspects to bring up with your provider before taking metformin.

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Final Thoughts

Living with PCOS can feel frustrating and uncertain, especially when your symptoms don’t follow a predictable or clear pattern. As such, management often takes time and a personalized approach. While metformin isn’t FDA-approved specifically for PCOS, it’s sometimes discussed as one option for addressing associated insulin resistance.

At the end of the day, however, the right approach is different for everyone. Working with a licensed healthcare provider can help you explore your options and determine the best next step for you and your health.