Why People Are Breaking Open Their Mounjaro Pens

Updated at 2:49 p.m. on August 15, 2024

By the time Lisa started breaking open her Mounjaro pens with pliers, she had run out of other ideas. She was 300 pounds. She had already tried bariatric surgery. (It had limited success.) She had tried getting her insurance company to cover Mounjaro. (It stopped after a month.) She had tried a cheaper copycat version from a compounding pharmacy. (It didn’t work as well, and she worried about what she was actually getting.) “I was absolutely desperate to stay on,” she says, but she could not afford the sticker price.

That’s when she learned online about a money-saving loophole: She could split a maximum-strength Mounjaro pen into the smaller doses she needed. (The single-use injection pens come in multiple concentrations that cost the same.) One pen became as many as six. A year of dose-splitting later, she has lost 75 pounds—at a fraction of the original cost.

Lisa is among a small number of patients who have taken to hacking their injection pens. (I’m identifying Lisa and other patients in this story by only their first names to protect their medical privacy.) As new drugs used for weight loss—which go by the brand names Mounjaro, Ozempic, Zepbound, Wegovy—have skyrocketed in popularity, patients have sometimes found that the one-size-fits-all dosing does not, in fact, fit all. Most dose-splitters are trying to save money, but others are managing side effects. They swap tips online. They take risks because they want to stay on a medication that is, by many accounts, utterly life-changing.

Breaking open the pens is risky; it can introduce microbes into the injected drug, which can lead to infection. “We do not condone these practices,”a spokesperson from Novo Nordisk, which makes Ozempic and Wegovy, told me. “People using Mounjaro or Zepbound should never ration,” a spokesperson from their manufacturer, Eli Lilly, reiterated. These drugs are sold in pens of different concentrations because patients need to ramp up gradually from a low dose to minimize side effects, before getting on the highest doses indefinitely for weight maintenance.

Doctors uniformly told me they did not recommend breaking open the injection pens. At the same time, they understood the forces that have pushed patients into doing so: Mounjaro, Ozempic, Zepbound, and Wegovy—which all mimic a natural hormone called GLP-1—are far more effective for weight loss than any obesity medications that came before them. They are so powerful, but so expensive that demand has far outstripped the willingness and ability of insurance to pay.

“There’s a lot of desperation that we’re seeing in our practice, and people looking for all kinds of work-arounds,” says Laura Davisson, the director of medical weight management at West Virginia University Health Sciences, who had many patients lose coverage after the state’s public-employee insurance stopped covering the new drugs. In rural communities especially, such as where Sarah Ro, the director of a weight-management program at the University of North Carolina, practices, obesity rates are high and few patients can afford to pay out of pocket. She’s heard of patients splitting doses to save money. “Oh my goodness,” she told me. “I’m going, What have we created?

Even putting costs aside, fixed-dose injection pens are not ideal for patients. After Ozempic was approved in 2017—the first of these drugs to be—doctors noticed that the standard regimen of increasing doses in four-week increments did not work for every patient. Some patients had debilitating side effects of nausea, diarrhea, or constipation at even the lowest, 0.25 mg, dose; they might need to start at only half or a quarter of that. Some needed to go up more slowly with in-between doses. And some might be “super responders,” losing weight so quickly that they never need the full dose at all.

Ozempic doses are actually quite easy to adjust, even if patients aren’t technically supposed to. Unlike subsequent drugs, Ozempic is packaged in multidose pens with dials. Only the official dosages are labeled—0.25 mg, 0.5 mg, 1 mg, 2 mg—but people quickly reverse-engineered how many dozens of clicks correspond to one milligram. Novo Nordisk officially cautions users to “not set the dose by counting the number of clicks.” But doctors told me they consider counting clicks to be pretty safe, and some even advised their patients on Ozempic to do so if a dose needs adjusting. “I don’t have a problem with it,” Davisson told me. Novo Nordisk uses the same pen for its insulin, allowing people with diabetes to choose the amount of insulin they need.

Wegovy contains the same active ingredient as Ozempic, semaglutide, but is approved for treating obesity instead of diabetes. (Using Ozempic for weight loss is off-label, and typically never covered by insurance.) Wegovy also comes at a slightly higher maximum dose and is packaged differently, in single-use, single-dose pens. That means patients on Wegovy cannot count clicks to adjust their doses—even though it contains, once again, the exact same drug as Ozempic. “It’s so frustrating,” says Katherine Saunders, an obesity-medicine doctor at Weill Cornell Medicine. Saunders told me she almost never follows the exact ramp-up schedule laid out by drug manufacturers, instead fine-tuning it based on how much weight a patient is losing and how many side effects they’re having. Single-dose fixed pens hamper her ability to personalize the regimen. When I asked if she would prefer flexible dosing as a doctor, she answered, “Yes, oh my gosh, yes, yes.” In Canada and Europe, Wegovy is actually sold in clickable pens. “We would love to have that flexibility,” says Fatima Cody Stanford, an obesity-medicine doctor at Harvard.

In the U.S., Mounjaro and Zepbound are packaged only in nonadjustable single-dose pens. (They both contain the same ingredient, tirzepatide, at the same doses, but Mounjaro is approved for diabetes and Zepbound for obesity.) This is why patients on tirzepatide—which is considered slightly more effective than the semaglutide in Ozempic or Wegovy—have gone to more extreme methods of breaking open these pens. The process is a lot more complicated, requiring sterile medical supplies and math to get the correct dosage.

Nicole started dose-splitting because she had awful vomiting and vertigo the day she increased her dosage from 2.5 mg to 5 mg. “I really was considering going to the emergency room,” she told me. She learned to split her first pen so she could ramp up more slowly with intermediate doses; the cost-saving is nice, too. Another dose-splitter, Phil, told me he has taught several of his friends how to split Mounjaro pens too. “For me, that’s really just a harm-reduction principle,” he said. “There are so many people this drug could be so life-changing for, but it’s just utterly, ruinously expensive.”

For her part, Lisa compared the risks of dose-splitting with the risks of her alternatives: Either going to a compounding pharmacy, whose copycat drugs might be unreliable or impure, or continuing to live with obesity. “I feel like this is an acceptable risk for me versus the risk of carrying an extra 130 pounds,” she said. She has another 55 pounds to go before she gets to that target weight loss of 130. Over time, the dose she needs has gone up, as it typically does. The six doses she got out of one pen became four, three, two, and now just 1.5. Eventually, she’ll probably need to get on the full maximum dose. She’s glad for the money she’s already saved, but dose-splitting can only work for so long. For most people, it’s not a long-term solution for a long-term medication.


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This article originally stated that a patient had bloodshot eyes while taking Mounjaro. In fact, she experienced this side effect with a different drug.