I THREW UP thousands of times when I was pregnant. This is not an exaggeration—for nine months, I vomited every day. On the good days, it was only two or three times. On the bad days, it was 10 or more. I threw up in the passenger seat of cars and kneeling on my bathroom floor and, once, in a trash can at a public park. I carried emesis bags everywhere I went, though I didn’t actually go very many places. I vomited after drinking water; I vomited after ingesting nothing at all.
For the first 12 weeks, I thought I was experiencing morning sickness. After all, up to 80 percent of women get morning sickness during pregnancy, with symptoms usually ebbing after the first trimester. But the vomiting didn’t end as I passed into the second trimester. I began to lose weight; my mother fretted over the gray pallor of my skin. I took work calls from the bathroom floor, muting myself to throw up.
I didn’t have morning sickness. I had hyperemesis gravidarum: severe and prolonged vomiting during pregnancy that can lead to weight loss and dehydration.
Hyperemesis gravidarum, known colloquially among sufferers as HG, affects between 0.3 and 3 percent of pregnancies, according to research. Some mothers-to-be are hospitalized for their symptoms, as I was several times during my pregnancy. Moms who suffer from HG are more likely to experience suicidal ideation, anxiety, and postpartum depression. Children born to mothers with HG are more likely to be born prematurely, be on the autism spectrum, or have learning disabilities.
Women with HG are often treated with the same drugs used for morning sickness, like Zofran, Diclegis, and Compazine, but for many, these drugs don’t put a meaningful dent in their symptoms. (I tried every medication I was offered. Nothing helped.) But now, there’s new hope on the horizon for HG sufferers, and it’s coming in the form of metformin, a 100-year-old drug used mainly to treat type 2 diabetes in the U.S.
Surprising Solutions, Found
Personal experience coupled with expertise is what led to this new focus on metformin for HG. One of the experts leading the charge is Marlena Fejzo, PhD, a clinical assistant professor at the Keck School of Medicine of USC. Fejzo herself had two pregnancies beset by severe HG: During her first, she lost 15 pounds, missed eight weeks of work, and was hospitalized twice before her symptoms eased halfway through the pregnancy. In her second, Fejzo was reduced to lying in bed with a catheter inserted into a vein in her collarbone in order to get her nutrition via a nutrient mix, before ultimately losing the pregnancy at 15 weeks.
While tragic, her familiarity with the condition is what motivated her to do this research. “There’s a silver lining,” she says.
First, Fejzo looked into what was known about HG at the time but came up with little information. It took decades of research for her to get to the idea that metformin may help prevent HG in women. The catalyst: While curating a list of things that had been shown to increase the hormone GDF15 (we’ll get to why this hormone is key), of which metformin is one, she decided to dive in and devote a significant portion of her research to investigating whether this medication for diabetes could be a real fix for HG.
So why did metformin jump out as an area for research in the first place? To make the connection, it’s important to understand why experts think HG exists, and it all comes down to that aforementioned hormone: GDF15. Present in all people—male, female, pregnant or not—GDF15 has long been recognized as a major contributing factor in nausea and vomiting during pregnancy. Fejzo and her fellow researchers posit that hypersensitivity to the hormone can result in HG (and published that thesis as part of a study that appeared in the journal Nature).
Metformin, however, increases the level of GDF15 in the blood. That might sound like a bad thing until you grasp what happens in early pregnancy: During that phase, the levels of GDF15 in an expecting mother rapidly increase (which is not great for someone who’s hypersensitive to it). So the idea is that taking metformin will “desensitize” women to the hormone before they become pregnant, resulting in less intense nausea and vomiting. “If it’s warm in your house and very cold outside, you will feel like you are freezing when you step outside, but if it’s cold in your house and you step outside, you may not feel overly cold because it’s the relative difference that makes it more or less shocking to your system,” Fejzo says.
In other words, women who are at risk of HG may be able to quell the severity of the disease in future pregnancies by taking metformin so their body gets used to GDF15 before that fast increase in early pregnancy. And evidence is bearing out the hypothesis: Taking metformin a month before getting pregnant was associated with an 82 percent reduction in the risk of severe nausea and vomiting in pregnancy and hyperemesis gravidarum, according to a 2025 study published in the American Journal of Obstetrics & Gynecology. That’s a gigantic number for a health condition that has felt pretty hopeless in the past.
Research in Real Life
The initial research into metformin to treat hyperemesis gravidarum is no doubt “promising,” says Fejzo, though further data is needed. Fejzo has recruited over 30 participants for an observational study in which people with a history of HG are trying metformin before pregnancy in order to prevent a recurrence; she is now gearing up to do a clinical trial.
One of those observational study participants is Madison Sweat, a 25-year-old mother from Windsor, California. Prior to her HG pregnancy, Sweat was a marathon runner. In the first 20 weeks of her pregnancy, she lost 20 pounds. Her situation became dire enough that she was placed on 24/7 IVs for eight weeks. She heard about metformin from other moms who were in the study and approached her doctor about it. When her child was 1, she immediately began taking it in preparation for a second pregnancy. Though she has dealt with some gastrointestinal distress (a common side effect when starting the medication), for her the possible benefits outweigh the costs. “Having a little bit of hope is worth all the side effects,” she says.
During Katrina Talty’s first pregnancy, the 28-year-old from Texas had debilitating hyperemesis gravidarum. “I tried many medications, and none worked,” she remembers. “It was so hard to keep food down, and I hated the thought of any food at all. It caused extreme depression, even to the point of self-harm and suicidal ideation.” Her mother had dealt with HG during all of her pregnancies, as had Talty’s sister, so Talty didn’t have much optimism for herself.
But when she heard about the possibility of metformin, she was willing to take a chance. She took the drug for five months before getting pregnant with her second child. Talty is now 23 weeks pregnant and says she’s doing “pretty dang well.” During her first pregnancy, she vomited 6 to 18 times a day. During her current pregnancy, she’s thrown up only a few times total. “I can’t believe it’s working so far,” she says.
Exploring Even More Possibilities
Metformin was first synthesized in the 1920s to lower blood-glucose levels and was first used to treat patients with diabetes in the 1950s. “This is actually one of the oldest drugs we have,” says Tannaz Moin, MD, an associate professor of medicine at UCLA. “There have probably been, at this point, hundreds of studies using the medication. We know it’s safe. We know most people tolerate it. And it’s not on patent anymore, so the cost is very, very low.”
The fact that metformin is so cheap and well studied has meant that its usage has broadened in recent years. Metformin has been found to reduce the viral load in COVID-19, to improve fertility in some individuals, to slow tumor growth in certain types of cancer, and to treat obesity by improving insulin resistance and decreasing appetite (and reducing weight), according to various studies and other research.
Metformin has gained a bit of a cult following among patients with polycystic ovary syndrome (PCOS) in particular. PCOS is a hormonal imbalance that affects about 1 in 10 women of reproductive age. Since the medication improves the body’s response to insulin—and insulin resistance is a hallmark of PCOS—it helps regulate ovulation and menstrual cycles.
Sarah Adler, a 34-year-old from Maryland, found metformin useful for PCOS symptoms. “It’s helped keep my periods regular,” she says. Adler also thinks it played a role in her reproductive health: “It probably contributed to me being able to get pregnant the first month we tried.”
Needless to say, women (and experts) are sold, and not just on its HG potential. “I really do consider metformin a wonder drug,” says Dr. Moin, referring to the wide variety of diseases and disorders for which metformin has been shown to be effective. “Researchers have even found antiaging effects,” she adds.
Indeed, preliminary studies have discovered that metformin may increase life expectancy by improving blood vessel function and the body’s responsiveness to insulin. Dr. Moin notes, however, that doctors aren’t really prescribing metformin specifically for its antiaging effects yet and that those findings were likely secondary side effects discovered in clinical trials. “We need more research in this area,” she adds. (But still, cool.)
Personally, I know deep in my bones that I want my daughter to have a sibling; I also feel physically ill when I think about being pregnant again. Hyperemesis gravidarum has a reported 89 percent recurrence rate, per one study, meaning that if you have it once, it’s likely you will have it in subsequent pregnancies. I barely survived it the first time. How can I do it again, this time while parenting a toddler?
When I first realized that metformin was being studied in this way, I cried, then messaged my ob-gyn to get a prescription. I don’t know if it will work for me, but the prospect that it might is buoying me. Every night after I eat dinner, I swallow my thick white pill of metformin and hope that next time will be different.
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