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Drug Info

How much metformin should you take for PCOS?

The starting dose of metformin for PCOS is 500 mg three times daily
Karen Berger medical writer and reviewer headshot
By | Sep. 11, 2024
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Key takeaways

  • Metformin is used for Type 2 diabetes but is also used off-label for managing polycystic ovary syndrome (PCOS).

  • The usual dose of metformin for PCOS is 500 mg by mouth three times daily.

  • Common side effects of metformin include nausea, vomiting, diarrhea, gas, and stomach discomfort.

  • Consult your healthcare provider for more information about your condition and treatment.

In this article:

Metformin is a prescription medication approved by the U.S. Food and Drug Administration (FDA) for controlling blood sugar in people with Type 2 diabetes mellitus. It is often the first-line treatment alongside lifestyle changes such as diet and exercise. Metformin is also sometimes used off-label for polycystic ovarian syndrome (PCOS). For PCOS patients, the usual dose of metformin is 500 mg by mouth three times daily, although the dosage is individualized for each patient. Continue reading to learn more about metformin for PCOS. 

How does metformin work?

Metformin, known by the brand name Glucophage, helps improve the body’s use of insulin. It decreases the amount of glucose the liver makes, reduces glucose absorption from the digestive system, and improves insulin sensitivity, helping the body’s cells use glucose more effectively. Metformin also helps regulate insulin secretion but does not increase the amount of insulin the pancreas produces. This leads to lower fasting insulin levels and a reduced overall insulin response.

Polycystic ovary syndrome (PCOS) is a common endocrine disorder that affects the metabolic system. PCOS causes irregular periods, high levels of male hormones (serum androgens), and ovulation issues. It is often linked to insulin resistance, where the body’s cells do not respond well to insulin, resulting in higher insulin levels.

Metformin can improve insulin sensitivity, lower insulin levels, and address insulin resistance in PCOS. It may also reduce serum androgen levels, help regulate menstrual cycles, and stimulate ovulation. While metformin can aid with infertility by helping women with PCOS conceive, it is not the first choice for those having difficulty getting pregnant. In such cases, medications like letrozole or clomiphene are usually more effective. Metformin may also aid in reducing gestational diabetes during pregnancy.

Additionally, for concerns like excessive hair growth (hirsutism), metformin use is generally not recommended; instead, oral contraceptives or antiandrogen medications may be better options.

RELATED: How the diabetic drug Metformin can be used to treat PCOS

According to the Prescriber’s Digital Reference (PDR), a typical dose of metformin for PCOS is 500 mg by mouth three times a day. However, doses may range from 500 mg per day to 3,000 mg per day. Another common dose is 850 mg twice a day.

The dosage provided above is for metformin’s immediate-release (IR) formulation. There is also a once-daily extended-release (ER) formulation of metformin, which may be prescribed for patients who experience stomach problems with the immediate-release (IR) formulation—or for various other reasons. If you have side effects from the IR formulation, discussing the possibility of switching to the ER formulation with your healthcare provider may be helpful.

When combined with clomiphene citrate (a medicine that helps with ovulation), metformin increases the chances of ovulation to about 86%, much higher than the 8% with clomiphene alone. 

Metformin treatment helps manage menstrual cycles and lower hormone levels. Still, it may be less effective in people with a higher body mass index (BMI), so weight loss and dietary changes are recommended.

RELATED: Metformin dosage, forms, and strengths

What is the lowest dose of metformin you can take for PCOS?

The general recommended dose of metformin for PCOS is 500 mg three times daily. However, healthcare providers often start with a lower dose to help the body adjust to the medication and minimize side effects. This gradual approach allows patients to build up to the recommended dose of 500 mg three times a day. It’s important to note that the exact dose may vary based on individual needs and responses to the medication. Follow the dosing recommended by your healthcare provider.

What are the side effects of metformin?

The most common side effects of metformin therapy are related to the stomach and intestines and include nausea, vomiting, diarrhea, gas, indigestion, and stomach discomfort. Headache and weakness are also common side effects. 

Serious side effects may also occur, requiring emergency or urgent medical care. These may include but are not limited to, allergic reactions, lactic acidosis (a buildup of lactic acid in the blood), and vitamin B12 deficiency. 

RELATED: Metformin side effects and how to avoid them

How to take metformin for PCOS

Here are some tips on taking metformin IR for PCOS. 

  • Before starting metformin for PCOS, tell your healthcare provider about your medical history and any conditions you have, including pregnancy, plans to become pregnant, or breastfeeding.
  • Tell your healthcare provider about your medications, including prescription and over-the-counter drugs, vitamins, and supplements.
  • Take metformin exactly as directed by your healthcare provider. Do not take more or less than recommended.
  • Take metformin with meals. This helps to reduce stomach problems.
  • Follow any dietary, exercise, and lifestyle recommendations your healthcare professional provides, especially if obesity is a medical concern. Weight reduction can be beneficial in the treatment of PCOS.
  • Avoid drinking alcohol during the use of metformin. Consult your healthcare provider for advice if you do consume alcohol.
  • Keep all follow-up appointments with your healthcare provider, as they may need to adjust your medication dose, and ensure you attend appointments for necessary blood work.
  • Occasionally, you may notice a soft mass in your stools that resembles metformin tablets; this is normal.
  • Notify your healthcare provider if you develop a fever infection, are scheduled for surgery, or have experienced any significant trauma, such as a car accident.
  • Ask your healthcare provider about checking your blood sugar levels, as metformin lowers blood sugar. If your blood sugar is too low, follow their instructions, such as consuming a specific amount of fast-acting carbohydrates like glucose tablets or juice.
  • If you take the extended-release (ER) form of metformin, swallow the tablet whole and do not chew or crush it.
  • For the liquid form of metformin, use a medicine-measuring device to ensure accurate dosing. Household measuring devices like kitchen teaspoons are unreliable and could lead to incorrect dosing.

What happens if you miss a dose?

If you miss a metformin dose, take it as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and return to your regular dosing schedule. Do not take a double dose to make up for a missed one.

The bottom line

Metformin is often used to manage Type 2 diabetes but is sometimes prescribed off-label for polycystic ovary syndrome (PCOS). It helps improve insulin sensitivity, regulate menstrual cycles, and may assist with ovulation. The usual dose for PCOS is 500 mg, taken three times daily, but dosage may vary. Consult your healthcare provider to develop a personalized treatment plan for your medical condition.