Is metformin safe while breastfeeding?

In this article:

• Metformin while breastfeeding
• Timing
• Side effects
• How to take it
• The bottom line

In this article

• Metformin while breastfeeding
• Timing
• Side effects
• How to take it
• The bottom line

Millions of people take prescription medications every day without a second thought. But once you become pregnant or are planning to breastfeed, you may start putting everything you take into your body under a microscope—even drugs as common as metformin—for fear that it may not be safe for your baby. So, can you take metformin to treat diabetes while breastfeeding?

“Metformin is an oral medication commonly used to manage Type 2 diabetes,” says primary care provider and women’s health expert Navya Mysore, MD. “It works by improving insulin sensitivity, decreasing glucose production in the liver (hepatic glucose production), and enhancing glucose uptake by our body’s cells.” Since hardly any metformin passes into breast milk, it is generally safe to take while breastfeeding. Here’s everything you need to know to keep you and your baby safe and healthy while taking metformin and nursing.

Can you take metformin while breastfeeding?

“While it’s always important to consult your healthcare provider to discuss your specific situation, metformin is generally considered safe to use while breastfeeding,” says Dr. Mysore. Studies that looked at levels of metformin in breastfeeding women who were taking different doses and at various frequencies determined that breastfeeding infants would receive less than 0.5% of their mother’s dosage of metformin—well below the 10% level that would be of concern for breastfed infants.

Metformin, also known by the brand name Glucophage XR, belongs to a pharmacologic class of drugs called biguanides that work by reducing glucose absorption from food in the intestines, decreasing glucose production in the liver, and increasing the body’s sensitivity to insulin. It is the most commonly prescribed medication antidiabetic agent for Type 2 diabetes mellitus. Why? It works. According to research published in Diabetes Spectrum, metformin alone reduces the progression of Type 2 diabetes by 31%. It is particularly effective in patients who are obese, have higher fasting blood glucose levels, have a history of gestational diabetes, or are on the younger side. So, while metformin is highly effective for the majority of people with Type 2 diabetes, it’s also a top choice treatment for Type 2 diabetics who are breastfeeding.

To put any metformin nursing considerations further into perspective, multiple studies also looked at the growth and development of breastfed infants whose mothers were taking metformin, finding no adverse effects. This was true for babies in whom metformin was undetectable as well as those in whom tiny amounts of metformin did come up on blood tests.

How long should I wait to breastfeed after taking metformin?

“There is such a tiny amount of metformin that passes into breast milk that there is not a need to wait a certain amount of time after taking metformin to breastfeed or pump,” says Jessica Madden, MD, a board-certified pediatrician and neonatologist, International Board-Certified Lactation Consultant (IBCLC) and Medical Director of Aeroflow Breastpumps. The minuscule amount of metformin found in breast milk is just one of two reasons that you don’t need to time breastfeeding around taking the medicine—the other is that the tiny amount of metformin in breast milk does not really change over the day.

Metformin comes as a tablet taken two or three times a day, an oral solution taken one or two times a day, or an extended-release tablet taken once daily. All of these are meant to maintain steady blood sugar levels throughout the day. As such, research has shown that levels of metformin in breast milk vary little over 24 hours, so there’s no need to adjust your medication or breastfeeding schedule.

Side effects of metformin while breastfeeding

“The main side effects of metformin are nausea, vomiting, abdominal pain, bloating, dizziness, headache, hypoglycemia (low blood sugar levels), and symptoms of lactic acidosis (high lactate levels in the blood),” says Dr. Madden. These are the primary side effects to look out for whether you are breastfeeding or not. According to the National Library of Medicine, you should talk to your healthcare provider if any of these symptoms are severe, don’t go away, or go away and come back.

Likewise, it’s worth giving your provider a call if you don’t experience any side effects at all for a time after you begin taking metformin. Since metformin will likely cause changes in your blood sugar levels as it starts working, at least mild side effects are common. If you don’t have any, it could be a sign that you are not on the correct dose.

Certain health problems are contraindications of metformin:

• Individuals with severe renal dysfunction
• Those with hepatic impairment
• Patients with unstable heart failure
• Older adults over 80 with renal impairment

While unlikely, you should look out for potential adverse reactions in your breastfed baby as well. “No adverse effects have been reported in breastfed infants whose mothers are taking metformin,” says Dr. Mysore. “But as a precaution, monitoring the infant for signs of hypoglycemia, such as drowsiness, pallor, sweating, or shakiness, is recommended, especially in infants with risk factors such as kidney problems or a premature infant.”

Then of course, there are the benefits you can expect to see from the use of metformin. “The main benefits to breastfeeding moms are that it helps to stabilize blood sugar levels and prevent complications from diabetes,” says Dr. Madden. There are a few additional potential perks for breastfeeding women. Dr. Mysore notes that metformin therapy is sometimes used to treat polycystic ovary syndrome (PCOS), which has been linked to low milk supply in mothers attempting to breastfeed. According to one study in Endocrinology, Oncology, and Metabolism, insulin resistance may be the key driver of low milk supply in women with PCOS, a problem that metformin could potentially improve—though more research is needed to confirm how much.

How to take metformin while breastfeeding

“Since metformin is a medication that’s compatible with breastfeeding, there are not any extra precautions that need to be taken,” Dr. Madden says. So, if you were taking metformin before you started breastfeeding, you should continue to take it the same way and with the same precautions and considerations in mind, the biggest of which is adherence to a set dosing schedule. If you miss a dose, you should take it as soon as you remember unless it is almost time for your next dose (or closer to your next dose than to the time you were supposed to take it). If it’s nearly time for your next dose, simply skip the missed one as opposed to taking a double dose.

As with any medication, it’s also important to talk to your healthcare provider about how you are feeling on the medication. You want to be at your best and healthiest when taking care of a new baby, and no medication should prevent you from doing so.

The bottom line

Metformin, one of the most commonly prescribed medications for Type 2 diabetes, is safe to take while breastfeeding. Studies have shown that minimal amounts pass into breast milk, and levels in breastfed infants are equally tiny or undetectable, with no adverse effects. There are no additional precautions you need to take if you are using metformin while breastfeeding, though it is important to look out for the most common side effects, both in yourself and your baby, and make sure you’re sticking to your dosing schedule.