Metformin For PCOS – 7 Reasons Why You May Want To Avoid It


Kym Campbell

Key Takeaways

Experts recommend against the use of metformin for PCOS.

It has limited benefits for both weight loss and fertility. Yet it has significant side effects and depletes nutrients.

There are better alternatives to metformin for all purposes related to PCOS. These include supplements, other drugs, and a PCOS diet.

Metformin is one of the most commonly prescribed treatments for PCOS. But it shouldn’t be. In this article, I describe the failures and shortcomings of metformin for PCOS. I also describe better alternatives. Chief among them are dietary interventions.

This is an evidence-driven perspective. But you can see how the consequences play out among women that take part in my free 30-Day PCOS Diet Challenge.

Experts recommend against the use of metformin for PCOS without diabetes. Even if you have glucose intolerance and are prediabetic. It’s only supposed to be for patients with type 2 diabetes.

In 2003, Dr. Robert Barbieri authored a guide on the use of metformin therapy to treat PCOS [1]. Many prescribing physicians may still rely on this guidance.

But, by 2018, Barberi and his colleagues had changed their recommendations. Based on more recent data, they no longer recommend the use of metformin as a first-line therapy for, “any indication” [2].

You can refer your doctor to their review of the literature here.

2. It’s Only a Band-Aid for Polycystic Ovary Syndrome

Metformin is a band-aid solution for preventing diabetes. The same is true in the treatment of PCOS. It only lowers your insulin levels as long as you’re taking it daily.

In 2002, the Diabetes Prevention Program Research Group quantified these benefits. They found that over 3 years, metformin reduced the incidence of newly developed diabetes cases by 31% [3]. But in a follow-up study, the majority of the benefit didn’t persist when the treatment was stopped [4]. This means that unless you make other changes, you’ll need to take metformin for life.

The same researchers compared metformin to a diet and lifestyle intervention. Their “lifestyle group” enrolled in a 24-week program focusing on diet and exercise. This group reduced their risk of type 2 diabetes by 58% [3]. This was significantly better than the 31% achieved by the metformin group. After 15 years, the lifestyle program still proved to be better than metformin at preventing diabetes [5]. For women in this study, the lifestyle program was also better at reducing microvascular complications.

This supports what I see within my PCOS support group. Many women that take part in my free 30-Day PCOS Diet Challenge take metformin. For those that can adapt to a PCOS diet, their insulin sensitivity improves dramatically. Over time, many of these women get key biomarkers back within normal ranges and stop taking this unnecessary drug.

3. It Doesn’t Help with Weight Loss

Many women are told that metformin helps with weight loss. That’s why “metformin PCOS weight loss” and “PCOS belly fat metformin” are such heavily searched terms on Google. A quick look at the scientific literature though shows that any weight loss benefits of metformin for PCOS are small at best.

Metformin can cause weight loss in non-diabetic people. In one study, people with severe insulin resistance lost more weight than insulin-sensitive people [6]. These benefits were independent of age, sex, and BMI. But the results are different for women with PCOS.

In a 2017 meta-analysis, Morely and colleagues reviewed 42 metformin studies in women with PCOS. They found that metformin had a slight improvement in the distribution of excess body fat. This led to a small improvement in waist to hip ratio. But there was no effect on body weight [7].

Meta-analyses like these are the most powerful assessments of scientific evidence. Smaller (and older) metformin weight loss PCOS studies have shown a slight benefit [8]. But the size of the effect was small. When considering the entire body of evidence, metformin is unlikely to help you lose weight.

The impact of dietary change overshadows any potential gains. This is because managing your diet is the best way to reverse insulin resistance. The right diet can also address chronic inflammation. This is another underlying mechanism driving PCOS weight gain. You can see this at play when PCOS women lose weight during my free 30-Day PCOS Diet Challenge. Many of their other symptoms go away too.

Learn more about how to lose weight with PCOS here.

4. It Doesn’t Help Much with Fertility

Metformin is often used for treating anovulatory infertility in women with PCOS. It’s really common and I include myself in this cohort.

But the benefits of metformin for fertility are unclear. A 2019 review investigated the effectiveness of metformin for fertility treatment in women with PCOS. They found that for a live birth rate of 19% with no treatment, adding metformin could raise this rate by 0 to 18% [9]. This large range reflects the paucity of good data. It means that metformin therapy on it’s could have no benefit at all for fertility.

The potential benefits also seem to depend on your body weight. The quality of evidence is poor on this point too. But it appears that metformin is more likely to help non-obese PCOS women than those that are overweight [9].

The Endocrine Society Clinical Practice Guidelines state that “[metformin] has limited or no benefit in treating hirsutism, acne, or infertility [10].”

These statements would be more definitive if metformin improved PCOS infertility in a meaningful way. Given the alternatives, it’s likely that metformin will be seldom used for fertility treatment in the future.

The women from my PCOS community provide powerful testimony to the use of diet over metformin. Here are some examples from my free 30-Day PCOS Diet Challenge.

5. Metformin Depletes Nutrients

There’s a lot of evidence showing that metformin use is associated with decreased vitamin B12 status.

A study on older adults found that metformin use was the best predictor of vitamin B12 deficiency [11]. The larger the dose and the longer you use metformin, the lower your serum B12 levels are likely to be [12, 13]. This is because metformin impairs B12 absorption [14-18]. Given the importance of B12, this is bad news for women with PCOS. A sub-clinical deficiency can affect pregnancy outcomes, vascular, cognitive, bone, and eye health [19, 20].

Unfortunately, many women are not informed of this risk.

Metformin can also affect other vitamins and minerals. This includes vitamin B1, folic acid, vitamin D, and magnesium [21]. Nutrient supplements may be required especially if you’re trying to conceive.

Learn more about the importance of magnesium for PCOS here. This article on vitamin D for PCOS explains why this nutrient, in particular, should be at the top of the list for most people.

6. Side Effects Are Common

In one study, approximately 88% of people experienced metformin side effects [22]. The most common side effects include diarrhea, heartburn, nausea, abdominal pain, bloating, and retching [23].

When I polled my PCOS support Facebook group, 78% reported adverse effects. If you’re looking for metformin for PCOS reviews, here’s what some of the respondents said.

“I was violently sick and couldn’t eat, everyone thought I had morning sickness so I had to stop taking it”.

“It made me super sick and it was a terrible experience”.

“I was always sick to my stomach on it”.

“I had numerous side effects, tiredness, nauseous, headaches, pain in my abdomen.”

“the metformin I started taking for fertility made me bleed for over 20 days and I had to go to urgent care due to anemia.”

Metformin also has other less common side effects. Lactic acidosis is a rare but serious side effect [24]. There have been many case studies of metformin causing liver injury [25-27]. Studies on rats also suggest an increased risk of Alzheimer’s disease [28].

The take home here is that metformin may be a safer drug, but it’s not without its risks.

7. There Are Better Alternatives for Insulin Resistance

The effectiveness of alternatives to metformin for PCOS is one of the biggest reasons not to take this drug.

Inositol supplements show the most promise for PCOS. For example, inositol supplements are more effective than metformin at improving menstrual frequency [29].

A 2019 meta-analysis compared the insulin-sensitizing effects of myo-inositol and metformin. Again, myo-inositol was found to be as good as metformin. Myo-inositol also performed as well as metformin when it came to improving testosterone levels, body mass index, and more [30].

One argument in favor of metformin use is for reducing the risk of ovarian hyperstimulation syndrome during IVF [31]. But inositol supplements also offer this protection [32, 33].

The natural herb, berberine, also shows great potential in patients with PCOS. Trials show that it can improve insulin resistance, blood lipids, and ovulation [34-37]. Meta-analysis suggests that berberine is as effective as metformin for improving insulin sensitivity [38].

Like inositol supplements, berberine is generally well-tolerated. This means fewer side effects and less disruption to your everyday life. It’s important to keep in mind though, that berberine is not safe during pregnancy.

Metformin was first approved for us in 1994. This was back when PCOS was known as polycystic ovarian disease. Since then, many other insulin-sensitizing drugs have come to market. New treatments like Ozempic, Wegovy, and Mounjaro may be suitable alternatives. Especially for patients that can’t tolerate the side effects of metformin.

Of course, the best alternative to metformin for PCOS is changing how you eat. Metformin’s health benefits come from its anti-inflammatory and antioxidant properties [39]. Its alteration of the gut microbiome is also key to its effectiveness [40-42]. Both of these mechanisms depend on your diet.

A PCOS diet reduces inflammation and improves gut health. It can also reverse insulin resistance. By addressing the underlying causes of PCOS, the right diet can displace the need for metformin. It also improves other PCOS symptoms at the same time.

The Bottom Line

It’s hard to justify metformin treatment for PCOS. Experts in the field no longer recommend its use as a first-line therapy for PCOS patients. Even for PCOS women with diabetes, metformin is a band-aid solution with better alternatives.

Metformin doesn’t provide meaningful weight loss results. Its cost/benefit as a fertility treatment is also tenuous given the alternatives. Metformin depletes important nutrients and has significant side effects. Ovasitol and berberine perform just as well but are much better tolerated.

A PCOS diet is the most important step for improving insulin regulation and fertility. A PCOS diet can displace the need for metformin and can further improve other PCOS symptoms.

Start your journey to better health and fertility by signing up for my free 30-Day PCOS Diet Challenge. If you aren’t ready to commit to 30 days try this free 3-Day Meal Plan instead.

FAQ

Are there any foods to avoid when taking metformin for PCOS? Anyone with PCOS should reduce or avoid refined carbohydrates, sugar, and processed foods. But there’s no specific dietary change needed to take metformin. Learn more about the foods to avoid with PCOS here.

What does metformin do for PCOS? Insulin resistance causes or exacerbates symptoms in the majority of PCOS patients. Metformin is an insulin-sensitizing drug that works to reverse insulin resistance. But metformin has shown limited benefits in numerous studies of PCOS women. There are now many good alternatives to metformin for PCOS.

What about metformin for PCOS acne? Metformin is an effective treatment for PCOS acne [43]. But given the side effects, many people will prefer alternatives. Learn more about treating PCOS acne here.

Metformin vs birth control for PCOS. Metformin may be a suitable alternative to oral contraceptives for lowering androgen levels in PCOS patients [44]. This can help with hirsutism and acne. The relative risk differences regarding diabetes, cardiovascular disease, or endometrial cancer remain unknown [45].

How long does it take for metformin to work for PCOS? Metformin takes 2-3 months to work, although some changes may happen sooner. Early signs metformin is working for PCOS include more energy and reduced sugar cravings. Improvements in menstruation and acne are often also observed.

How long to take metformin for PCOS? Metformin is often used as a long-term treatment. That could mean many decades for some people. The diabetes prevention program has followed patients for more than 15 years [5].

What is the typical metformin dosage for PCOS? As well as getting the dose right it’s important to understand how to take metformin for PCOS. The starting dose for metformin is typically 250 mg taken twice a day. This should be gradually increased every 2 weeks to reach the desired therapeutic dose. The target dose for effectiveness is between 1500 -2500 mg/day. There’s no specific metformin dosage for PCOS weight loss.

What is the lowest dose of metformin you can take for PCOS? 1500 mg per day is the most common metformin dosage for PCOS used in clinical trials. Doses of 1000 mg per day have been used in trials when taking metformin and clomid together [46].

What happens if you miss a dose of metformin for PCOS? Provided your blood sugar levels are being managed, missing one dose shouldn’t matter too much. If it’s been less than a few hours since you missed the dose, take the missed dose right away. Otherwise, skip the dose and continue on your regular schedule at the next dose. Don’t take a double dose.

What to expect when taking metformin for PCOS. It’s common to experience side effects when starting metformin. Nausea and gut discomfort are particularly common.

Ready to Take Action?

  • Join my free 30-Day PCOS Diet Challenge here. This is a unique program where you’ll receive weekly meal plans, shopping lists, and helpful video lessons. You’ll also be part of a motivated and inspiring community of like-minded women.
  • Download my free 3-Day PCOS Diet Meal Plan here. This is perfect for getting started if you aren’t ready to commit to 30 days.
  • Join my PCOS Monthly Meal Planning Service here. This service includes hundreds of PCOS recipes within a pre-populated, yet customizable meal plan. It’s designed to save you time and help you apply a PCOS diet.
  • Sign up for my Beat PCOS 10-Week Program. This is a comprehensive program that covers diet, PCOS-centric emotional eating, exercise, stress management, and much more. All within a support group environment. The 10-Week Program includes the same recipes and meal plan as my monthly meal planning service.

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References

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