Mayim Bialik had ‘uncontrollable’ GI symptoms after taking a GLP-1. What doctors say about severe side effects.

Three separate doctors suggested Mayim Bialik try a GLP-1 medication to help manage her thyroid condition, Graves’ disease. She knew that there could be side effects, but nothing prepared the Big Bang Theory actress for the “nightmare” that followed, she wrote in an essay for the Free Press. 

For weeks, Bialik could barely leave her house due to “explosive, uncontrollable diarrhea.”  She also had body aches, cramping, bloating, sulfur burps and “sneezing attacks” that struck any time she tried to eat or drink (a phenomenon known as snatiation). Bialik said her gastrointestinal (GI) issues left her feeling so weak and dehydrated that a nurse had to come to her home to administer an IV, as she was unable to keep down even a “sip of water.”

“What shocked me was how unsurprised my doctor and this nurse seemed,” Bialik wrote. “Extreme side effects, they told me, were not unusual. I couldn’t wrap my head around that — and seeing a gastroenterologist at this stage was deemed overly conservative. How could a reaction even half as severe as mine be considered normal?”

Today a reported one in eight adults are on a GLP-1 medication, and nearly one in five have taken one at some point in their lives. These drugs can be used for weight loss as well as to manage conditions like type 2 diabetes — and data suggests they may even offer protective benefits against different types of cancer. For many people, GLP-1s have been game changers in their lifelong battles against obesity and many other health conditions. But unpleasant side effects are not uncommon, and, as Bialik discovered, they can sometimes be severe.

What are the side effects of GLP-1s? 

Side effects vary depending on which medication someone is taking (Bialik did not disclose what particular drug she was prescribed) and the dose. The most common side effects in GLP-1 medications are nausea, vomiting, diarrhea and constipation, Dr. Michelle Gordon, an obesity medicine physician who writes about women’s health on Substack, tells Yahoo.   

While some people do experience “sulfur burps,” as Bialik did, Gordon says those are more likely to occur after eating foods high in saturated fats. GLP-1 medications work, in part, by slowing gastric emptying, meaning the rate at which food moves through the GI system. It’s part of the mechanism that helps people feel fuller for longer. However, Gordon says, “when the stomach is slow to empty, gas gets built up, and it’s got to go somewhere. The easiest way is for it to come back up” —  in the form of sulphur burps — “instead of going back down through the full GI tract.”

Thus far, Gordon has not seen a patient experience the sneezing effect Bialik says she did after taking the GLP-1 drug, but some people have reported allergy-like symptoms.

How common are side effects like Bialik’s?  

In clinical trials for the GLP-1, Wegovy, 44% of people taking the drug reported nausea. Another 30% said they had diarrhea, and 24% of people experienced constipation or vomiting. Only 6.8% of trial participants quit taking the drug as a result their side effects. The drop-out rate due to side effects was similar in trials of Zepbound; between 4.8% and 6.7% of participants stopped taking the shots during the study, depending on the dose they were on.

But real-world data suggests that severe symptoms may be more common than that. Nearly 15% of people who took a GLP-1 drug to treat obesity stopped taking the drugs due to side effects, according to a 2025 survey conducted by KFF. And, as Bialik notes in her essay, more than 4,000 Americans have filed lawsuits against GLP-1 drug manufacturers over what they claim are life-altering side effects. 

Meanwhile, a study published in Nature Health in April analyzed Reddit data and found that many GLP-1 users were taking to the online forum to report side effects not captured in clinical trials. The most prevalent symptoms were GI ones, but they also reported more unusual ones, such as irregular periods. 

And, anecdotally, other public figures have said their GI side effects led to them stop taking weight loss drugs: Comedian Amy Schumer previously said that she experienced vomiting as a side effect of the GLP-1 medication Wegovy and ultimately quit taking it. (She has since had a positive experience on Mounjaro.) And influencer Remi Bader said that a GLP-1 drug made her so sick she was “throwing up every day” while on the medication. 

Are GI side effects typically this severe? 

Dr. Brian Wojeck, an assistant professor of endocrinology at Yale University and a weight management specialist, tells Yahoo that while GI side effects are common with GLP-1 drugs, most patients who experience them can tolerate them and they do not reach a severe level. He adds that while some patients are hospitalized for side effects such as pancreatitis or gallbladder issues, problems this severe are extremely rare. 

More common side effects are typically most significant in the first two weeks on the medication, as a person’s body gets used to the drug, Wojeck says. Gordon adds that she’s only seen side effects as severe as Bialik’s in patients who were taking too high a starting dose (the actress wrote that her symptoms set in after her first shot of the lowest dose of her medication). If someone starts with too high a dose, Gordon says, their body may react with increased GI distress. She adds that compounded versions of GLP-1 medications come in vials rather than pre-dosed pens, making it easier for patients to accidentally over-medicate. 

In many cases, GI side effects can be managed or prevented by some slight tweaks to people’s habits, such as avoiding alcohol, spicy food, and high-calorie or fatty foods, and staying hydrated, Wojeck and Gordon say. 

However, “there is a subset of people that have significant diarrhea or significant nausea that they simply do not tolerate the medicine, and these are not the right medicines for them,” says Wojeck. It’s not possible to know in advance how someone may or may not tolerate the drugs, Wojeck. “If you try them and you don’t tolerate them, we need to back off — and that’s OK,” he says. If that is the case, you can talk to your doctor about what options might be a better fit. 

That’s the advice Bialik was ultimately given when she did finally see a gastroenterologist. The specialist told her she did not “meet the bar” to be on the medication. 

Gordon notes that severe side effects from GLP-1s are possible, but so are serious benefits, including their potential to prevent many health issues, such as obesity-related cancers and diabetes. But anyone taking or considering taking these medications must make their own risk-benefit calculation. 

“One person’s experience is not every person’s experience,” she says. “What worked for you may not work for the next person.”