Some patients taking GLP-1 drugs to lose weight or manage Type 2 diabetes are discovering an emerging potential side effect from the blockbuster class of medications: the loss of pleasure or an emotional numbness that’s been dubbed “Ozempic personality.”
It’s not common and doctors don’t know if it’s a direct reaction to the drugs, but it may be a sign to reduce the dose or stop the medication if the impact becomes severe, experts say.
Dave Knapp noticed the change about three years after he started Mounjaro.
“I really started to discover that I was really not having the same amount of pleasure or seeking the same amount of pleasure in some of the activities that I once enjoyed,” Knapp, the founder of the “On The Pen” podcast, which focuses on GLP-1s and obesity medicine, told NBC’s Anne Thompson.
“A lot of the things that I used to really get excited about, I was no longer seeking out.”
His first “big red flag” was baseball. He’d always been an avid fan of the sport, especially the Chicago Cubs, but noticed he hadn’t been following it at all while on the drug.
Dave Knapp noticed he cared less about his baseball team, the Chicago Cubs, once he started taking a weight-loss drug.Courtesy Dave Knapp
When Knapp’s weight loss plateaued and he needed to step up his activity, he found it hard to go to the gym even though he’d always enjoyed moving his body and had powerful motivation to maintain his weight loss. Knapp, the father of four young children, had struggled with obesity. His own father died of a heart attack at 54.
“It was just like the drive and the motivation that maybe once would have been there was no longer there at all,” Knapp said.
“I really was motivated in theory to want to get into the gym more, to want to re-evaluate my diet, but I was finding it just very hard to take step one, which was not normal for me.”
‘It Is Not In Their Heads’
The medical name for the phenomenon is anhedonia, said Dr. Christopher McGowan, a gastroenterologist and obesity medicine specialist based in North Carolina.
It’s unexplored and anecdotal in the context of GLP-1 drugs, but some patients report a general decrease in interest, pleasure and excitement in activities they previously enjoyed like eating out or socializing, he noted.
“It is not in their heads. We are absolutely hearing this from people,” McGowan told TODAY.
“One patient described to me as just a feeling that the lights had dimmed, but you couldn’t really explain why.”
Anhedonia is not currently listed as a side effect for Ozempic, Wegovy, Mounjaro or Zepbound, some of the most popular weight loss drugs currently available.
Lilly, the maker of Mounjaro and Zepbound, told TODAY in a statement: “Patient safety is Lilly’s top priority, and we actively monitor, evaluate, and report safety information for all our medicines. If anyone is experiencing any side effects while taking any Lilly medication, we encourage them to speak with their healthcare provider. Additionally, anyone experiencing side effects from a Lilly medicine can call The Lilly Answers Center at 1-800-LillyRx (1-800-545-5979).”
Novo Nordisk, the maker of Ozempic and Wegovy, said in a statement, in part, that the medications’ “efficacy and safety have been extensively demonstrated in people with obesity/overweight with robust evidence for improving health outcomes. … We remain committed to patient safety and transparency by maintaining up-to-date safety information and collaborating closely with health authorities and regulatory bodies worldwide.”
It’s unclear how frequently anhedonia occurs in people taking GLP-1 drugs because it wasn’t studied in clinical trials, but it’s not common — far more patients report positive effects like improved mood, confidence and energy, McGowan said.
The medicines work by targeting receptors in the brain and body, including the hunger and reward centers, so food tastes less delicious, leading to weight loss. But when interest in food suddenly changes, life can feel different since food is deeply tied to emotion, comfort, celebration, stress relief and social connection, the doctor noted.
The known side effects of GLP-1 drugs, including nausea, bloating and fatigue, can also impact mood, energy and interest in activities, he added.
Knapp is now taking a lower dose of a weight-loss drug after a higher dose seemed to reduce his desire to exercise.How To Get Help
If a patient feels numb, that could be concerning.
“If you’re not getting out of bed and not starting your day and really not putting the same effort level and getting the same joy out of your everyday experiences, that’s a problem,” McGowan said.
“Knowing that exercise is so important, if someone says, ‘I don’t even feel like working out anymore when I’m on this medicine,’ that, to me, is a problem.”
McGowan advised patients to report any emotional symptoms to their doctor. Their dose may need to be adjusted or they may have to switch to a different GLP-1 drug. Depending on the severity of symptoms, the medicine may need to be discontinued, he said. But patients should never abruptly stop their medication without first speaking with their medical team.
Be intentional about building new sources of reward and fulfillment into your life, including new hobbies and experiences. Exercise is “the greatest mood booster of all,” McGowan said, so he recommends his patients get active.
Knapp stopped Mounjaro in December, went on the Wegovy pill for about a month, then stopped all GLP-1 drugs for 40 days.
“What I learned for me, in talking with my doctors, was that the dose was simply too high for me, and that at the right dose and the right amount, it would give me the metabolic effects I was looking for, allowing me to have the proper level of motivation and drive to do the things I love to do,” he said.
He’s now on Zepbound, which has the same active ingredient as Mounjaro, but takes a lower dose of the GLP-1 drug, which still helps him manage his blood sugar and control his appetite, but doesn’t erase his motivation to go in the gym, Knapp said.
He advised other GLP-1 patients to pay attention to their mental health.
“If you’re hearing frequently from the people that you love, like, ‘Hey, it just seems that you’re less motivated to do some of the things that you used to love. What gives?’ I wouldn’t brush that off immediately,” Knapp said.
“I would maybe consider and take a mental inventory of what are the things that maybe you used to enjoy that you didn’t, and then bring that to your doctor.”