Metformin for PCOS: Dosage, usage, side effects

Metformin is a medication doctors typically prescribe as a first-line treatment for diabetes. But, sometimes, they may also prescribe it for treating PCOS because the medication acts to lower blood insulin levels and can stimulate ovulation in people with PCOS. Learn more about metformin for PCOS treatment. 

Black woman sitting on a coach taking a pill with a glass of water

Key takeaway

  • Metformin is one of the medications used for treating type 2 diabetes and gestational diabetes. But one of its “off-label” uses is for managing insulin resistance and treating hormonal imbalances in people with PCOS.
  • The dosage of metformin for PCOS varies depending on your needs and is typically started at a low dose and gradually increased to reduce possible side effects.
  • Proper usage of metformin involves taking it with meals to reduce gastrointestinal side effects and adhering to the prescribed treatment plan as directed by a healthcare professional.
  • While metformin is generally tolerated, common side effects may include gastrointestinal symptoms such as nausea, diarrhea, and abdominal discomfort.

Polycystic ovary syndrome (PCOS) is a common hormonal disorder that affects 4–12% of women in their reproductive years. This condition can cause hormonal imbalances, irregular periods, excess levels of androgen, and cysts in the ovaries. Irregular periods with a lack of ovulation can sometimes make it difficult to become pregnant.

PCOS is a challenging condition for people who have been diagnosed with it, not only because of the different discomforts and symptoms it causes but also because its treatment can be complicated. Some treatments focus on reducing some of its symptoms, while others aim to target its root cause. Metformin is one of the medications that healthcare professionals sometimes prescribe to manage this condition.

What is metformin?

Metformin is a drug that was approved by the U.S. Food and Drug Administration (FDA) primarily for treating type 2 diabetes. It belongs to the class of drugs called biguanides, and it works by helping you manage your blood sugar levels.

Metformin works mainly by reducing the amount of glucose produced by your liver and increasing your body's response to insulin, a hormone that helps the cells of the body take in sugar (a breakdown of carbohydrate foods) and use it as a source of energy. 

Notably, metformin does not increase insulin levels in your body, but rather, it improves insulin sensitivity, allowing your body to use insulin more effectively.

In addition to its use in diabetes management, metformin has been studied for its potential benefits in other areas, such as polycystic ovary syndrome (PCOS) and metabolic syndrome.

While it is not licensed for use in treating PCOS in some countries, like the UK, healthcare professionals sometimes use it as an “off-label” treatment to help with fertility and symptom improvement in people with PCOS.

The role of metformin in treating PCOS

Metformin acts in different ways to help treat conditions like PCOS, and one prominent way it does this is by reducing insulin levels in individuals. 

Different studies have linked PCOS to insulin resistance, with strong evidence suggesting that people with PCOS have a high chance of having insulin resistance—a condition whereby the cells of the body don’t respond to insulin, making it hard for the cells to use insulin.

The pancreas in people with this condition keeps making insulin to help manage blood glucose. The result of this is that insulin starts circulating in high amounts in the body. And a high amount of insulin stimulates the excess production of androgen hormones, which is one of the major contributors to PCOS development.

So, by taking metformin, people with PCOS may be able to manage their insulin sensitivity, causing their cells to take in more glucose and reducing the amount of insulin circulating in the blood.

Here is a breakdown of the role metformin plays in treating PCOS:

1. Improves insulin sensitivity

Since insulin resistance is common in people with PCOS and contributes to the development of this condition, metformin can help manage the syndrome by helping the body use insulin more effectively. Its action can treat the issue of insulin resistance.

2. Regulates menstrual cycle

One major symptom of PCOS is irregular menstrual cycles or even the absence of menstruation (amenorrhea). Metformin plays a significant role in restoring regular menstrual cycles as well as promoting ovulation.

3. Enhances fertility

When metformin is used in combination with lifestyle changes such as exercise, dieting, and fertility medications, it can improve fertility outcomes in women with PCOS who want to get pregnant.

PCOS is associated with an increased risk of developing metabolic complications, such as type 2 diabetes and heart disease. Metformin can help reduce these risks by improving glucose metabolism, reducing insulin resistance, and aiding in weight loss.

Dosage of metformin for PCOS (and how to use it)

When you start taking the immediate-release oral form of metformin, the usual recommendation for people with PCOS is to begin with a dose of 500 mg once or twice a day. This helps your body get used to the medication and reduces the chances of experiencing stomach-related side effects.

As you continue taking metformin, your doctor may increase the dose gradually. Every week, they may raise the dose by 500 mg. For example, in the second week, you might take 1,000 mg per day (500 mg twice a day). In the third week, the dose might be increased to 1,500 mg per day (500 mg three times a day), and so on.

The purpose of this gradual increase is to give your body time to adjust to the medication and minimize any stomach-related side effects like nausea or diarrhea.

Does metformin increase fertility?

Yes, metformin does improve fertility. One of the main effects is that it regulates hormone levels in women with PCOS. It significantly works by reducing insulin levels in the body.

When your insulin levels are high, it can cause imbalances in other hormones like luteinizing hormone (LH) and androgens (male hormones). These imbalances can affect the menstrual cycle and contribute to fertility problems. Metformin helps bring these hormone levels back to normal.

When hormone levels are normalized, the menstrual cycle often becomes more regular. This means that women with PCOS who were having irregular periods may start having periods at predictable intervals. This is important because regular menstrual cycles are necessary for ovulation and the potential for pregnancy.

So, when women with PCOS take metformin, it helps regulate their menstrual cycles and increases their chances of getting pregnant.

It's important to note that metformin alone may not work for all women with PCOS to achieve pregnancy. Other medications, like clomiphene citrate, when combined with metformin, may better increase the fertility success rate. 

Can metformin help you lose weight with PCOS?

Yes, metformin can help you lose weight if you have PCOS.

Research shows a significant decrease in body weight in obese and severely obese women treated with metformin, independent of lifestyle modifications such as diet and exercise.

It also suggests that metformin may have a positive impact on belly fat reduction when combined with a low-calorie diet. While metformin may have some potential for modest weight loss in some people with PCOS, the evidence is not consistent, and lifestyle changes remain an important part of managing weight with PCOS.

How much weight can you lose on metformin with PCOS?

There is not much available information on the exact amount of weight you can lose if you have PCOS and are on metformin.

However, researchers in a study found out that people who take metformin lost at least 5% of their body weight in the first year, and they also maintained their weight loss over six to fifteen years. This percentage is a general review of the amount of weight people who take metformin can lose and is not specific to women with PCOS.

How long does it take to see results from metformin medication?

The duration of time it takes for you to see results when taking metformin for PCOS is unclear and depends on several factors, including weight and other co-existing health conditions. 

However, a study shows that metformin is likely to take longer to induce ovulation in people with PCOS if taken alone as compared to when combined with clomiphene citrate.

Side effects of taking metformin for PCOS

The major side effects associated with metformin treatment are related to the gastrointestinal system. They include:

Diarrhea, nausea, and vomiting are common side effects that can occur when you start taking metformin, but they are likely to stop with time. You can reduce the risk of having these side effects by taking metformin with food. You can also speak to your doctor about making adjustments to the dosage you are taking.

The extreme side effects of metformin may include lactic acidosis. This rarely occurs, but when it does, it is often serious and is considered a medical emergency. Symptoms of lactic acidosis include trouble breathing, dizziness, lightheadedness, a fast or slow heart rate, a cold feeling, or muscle pain. If you notice any of this while taking metformin, consult your doctor immediately.

Metformin alternatives: Other treatment options for PCOS

While metformin can help manage PCOS, there are other alternative treatment options available, such as:

  • Lifestyle modifications: A balanced, nutritious diet (which includes whole grains, lean protein, and vegetables) and regular physical activity can help regulate hormones, improve insulin sensitivity, and promote weight loss.
  • Oral contraceptives: Birth control pills are also prescribed to regulate menstrual cycles and reduce androgen levels in PCOS. They help control symptoms such as irregular periods, excess hair growth, and acne.
  • Anti-androgen medications: This medication blocks the effects of androgens (male hormones) and can be prescribed to manage symptoms like excessive hair growth, which is a common symptom in people with PCOS. Spironolactone and flutamide are examples of anti-androgen drugs commonly used in PCOS treatment.
  • Ovulation induction: For women trying to conceive, medications such as clomiphene citrate (Clomid) may be prescribed to stimulate ovulation.
  • Surgery: In certain cases, surgical procedures like ovarian drilling or ovarian cyst removal may be considered to improve fertility or alleviate symptoms.
  • Insulin-sensitizing agents: Besides metformin, other medications like thiazolidinediones (pioglitazone, rosiglitazone) may be prescribed to improve insulin sensitivity in women with PCOS.

Final thoughts

Metformin is a treatment option for PCOS that works by addressing insulin resistance and regulating hormonal levels. 

By understanding the appropriate dosage, usage guidelines, and potential side effects, you will be able to work closely with a healthcare professional to utilize the benefits of metformin as part of your treatment plan.

If you notice any of the side effects mentioned above while taking metformin, consult a doctor immediately for proper management.