What happens when you stop taking Mounjaro?

Health experts have described Mounjaro® (tirzepatide) as part of “a revolution…in the treatment of cardiometabolic disease,” with participants on the highest dose losing more than 20% of their body weight. But what happens when you stop taking Mounjaro? 

As with many drugs used for weight loss, Mounjaro’s relatively newness means there’s limited evidence on how long people need to take it or what they need to do to maintain weight loss after they stop. Here’s what we know about how Mounjaro works and what happens when people stop taking it. 

What is Mounjaro? 

Mounjaro, a brand-name medication with the active ingredient tirzepatide, is a novel drug that the U.S. Food and Drug Administration (FDA) approved in May 2022 for managing blood sugar in people with type 2 diabetes. While it launched initially as a diabetes drug, early studies revealed its effectiveness for weight loss, prompting many health care providers to prescribe it off-label for weight loss. In November 2023, the FDA approved tirzepatide for weight loss under the brand name Zepbound®. 

Clinical trials have shown that tirzepatide is one of the most effective weight loss drugs currently available. In a 2023 study published in Nature Medicine, participants on the highest dose of Mounjaro or Zepbound (15 mg) lost an average of about 18% of their body weight after taking the drug for 36 weeks.

How does Mounjaro work? 

One reason Mounjaro is so effective for blood glucose control and weight loss is because it works on two different types of hormone receptors in the body. First, it acts as a GLP-1 agonist, which means it activates the glucagon-like peptide-1 receptors in the digestive system and the brain. In addition to releasing insulin to lower blood sugar, these receptors trigger feelings of fullness, so you naturally eat less. They also trigger a slowing of the digestive system, so food takes longer to move out of your stomach, leaving  you feeling fuller for longer. This is the same effect as other GLP-1 medications like Ozempic® and Wegovy®, which contain the active ingredient semaglutide.

However, Mounjaro also activates a second hormone receptor, the GIP receptor. Like GLP-1 receptors, GIP receptors signal your body to release insulin, which lowers blood sugar after a meal. Studies show a dual GLP-1/GIP agonist like Mounjaro can be even more effective for weight loss than a GLP-1 agonist alone. Researchers are still studying exactly why, but GLP-1/GIP medication seems to support weight loss independent of diet, prompting your body to shift its energy balance and increase its energy use even on a high-calorie diet. 

As a result, for many, Mounjaro can be a supportive tool for significant weight loss: In the SURMOUNT-3 phase 3 clinical trial on tirzepatide (Mounjaro) for obesity and overweight, participants who took the drug and made lifestyle changes for 72 weeks, following 12 weeks of intensive lifestyle changes, lost on average 24.3% to 26.6% of their body weight. On average, participants taking the placebo lost 3.8% to 4.5% of their body weight, with those same lifestyle changes over the same period.

Will you regain weight if you stop taking Mounjaro? 

So what happens if you stop taking Mounjaro? Because its use as an anti-obesity medication is still relatively new, there hasn’t been a lot of research on the best way to maintain weight loss achieved with tirzepatide if or when you stop taking it. 

However, in the SURMOUNT-4 clinical trial, participants who stopped taking tirzepatide regained some of the weight they had lost. During the trial, all participants took tirzepatide for 36 weeks and lost an average of 20.9% of their body weight. Participants were then randomly assigned to continue with tirzepatide or a placebo for the following year. Those who continued on the drug lost more weight (an additional 5.5% on average), while those on the placebo regained 14% of the weight they had lost. 

This same study also looked at waist circumference (WC),  one indicator of a person’s risk for health problems like heart disease or type 2 diabetes. (Use our free waist-to-hip ratio calculator to gauge your risk.) After a year, patients who continued taking  tirzepatide reduced their WC, on average, 22.5 cm. (Those given the placebo saw an initial reduction in WC of almost 17 cm while on tirzepatide only to regain an average of 7.8 cm in WC after a year off of the drug.) 

Will your blood sugar increase if you stop taking Mounjaro? 

Mounjaro is often used to treat type 2 diabetes because it controls blood sugar by improving insulin sensitivity and enhancing the release of insulin in the body. If you stop taking Mounjaro and regain weight,  your body may return to its previous levels of insulin secretion, potentially raising your blood sugar. If you have type 2 diabetes or prediabetes, you already have higher glucose levels, which can put you at higher risk for blood sugar spikes. If this is the case, you may need to replace Mounjaro with another medication to control your blood sugar. 

That said, research suggests losing weight with tirzepatide may help those with obesity and prediabetes prevent or delay the onset of type 2 diabetes. A 176-week study published in New England Journal of Medicine’s November 2024 issue found that taking tirzepatide for a little more than three years resulted in “substantial and sustained weight reduction and a markedly lower risk of progression to type 2 diabetes than that of placebo.” The health benefits continued even 17 weeks after stopping the drug. 

The study followed people with obesity and prediabetes who took 5 mg, 10 mg, or 15 mg weekly doses of tirzepatide (or placebo) for 176 weeks, then monitored them for another 17 weeks after stopping the treatment or placebo. At 176 weeks, 13.3% of the placebo group had progressed to type 2 diabetes, compared to just 1.3% of those in the tirzepatide group. After 17 weeks off treatment or placebo, 13.7% of the placebo group had advanced to type 2 diabetes, compared to just 2.4% of the group who’d received tirzepatide. 

Are there side effects—and will they stop if you stop taking Mounjaro?

Mounjaro does have some known potential side effects, most commonly nausea, vomiting, diarrhea, constipation, stomach pain, and acid reflux. 

More serious but less common side effects include pancreatitis, gallbladder disease, worsening of diabetic eye disease, and pulmonary aspiration under anesthesia or deep sedation. Severe persistent abdominal bloating or pain, acid reflux, a feeling of fullness after eating just a few bites of food, nausea, and vomiting (including vomiting undigested food eaten a few hours earlier) may be symptoms of gastroparesis (stomach paralysis). 

Those with a personal or family history of medullary thyroid cancer or multiple endocrine neoplasias should not use Mounjaro, which carries a black box warning about the risk of thyroid C-cell tumors. (Find detailed side effect and risk information on our dedicated Mounjaro page.) 

Side effects are most common when starting Mounjaro or increasing the dose; for many, these side effects resolve once the body adjusts to the medication—or they stop taking the medication. In the SURMOUNT-4 trial, 68.2% of those taking tirzepatide experienced treatment-related side effects. The most common were nausea, diarrhea, constipation, and vomiting; most symptoms were characterized as mild to moderate. Only 7% of the participants felt the side effects were severe enough to stop taking the drug, and side effects were most pronounced when dosage increased.

Do you have to take Mounjaro forever? 

Researchers continue to explore the best ways to maintain weight and health goals after losing weight with an anti-obesity drug. Doctors increasingly believe that “obesity should be regarded like other chronic diseases where chronic therapy may be needed to maintain treatment benefits,” as Dr. Jeff Emmick, MD, Ph.D., a senior vice president at Eli Lilly and Company, explained in a 2023 news release detailing the weight loss results among participants of the SURMOUNT-3 and SURMOUNT-4 trials. 

If you need to stop taking Mounjaro, talk with your health care provider about how you can best maintain the health benefits you gained and make them lifelong. 

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Found is not affiliated with or endorsed by Eli Lilly and Co., the owner of the registered trademarks Mounjaro® and Zepbound®, nor is it affiliated with or endorsed by Novo Nordisk A/S., the owner of the registered trademarks Wegovy® and Ozempic®. The content provided is for informational purposes only and should not be used as a basis for diagnosing or treating any health condition, or for determining actual costs incurred. Always follow your health care provider’s instructions to ensure safe and effective management of your health conditions. Certain medications are only FDA-approved to treat conditions other than weight but may be prescribed to help aid in weight loss. Prescriptions are up to a medical provider’s discretion. For key risk information by drug, visit the Found medication page.