Drugs like Ozempic, Mounjaro and Wegovy are extremely effective for weight loss. But shedding pounds isn't the only change patients might experience. 

Tirzepatide — sold under the brand name Mounjaro — and semaglutide — sold under the brand names Ozempic and Wegovy — are administered once a week by shot. Mounjaro is known as a GIP and GLP-1 receptor agonist while Ozempic and Wegovy are known as GLP-1 receptor agonists.

Mounjaro and Ozempic were initially sold as diabetes medications, while Wegovy is specifically for weight loss. The medications are currently administered by injection, but the drug in Wegovy and Ozempic may soon be available in pill form. Wegovy is FDA-approved for weight loss; Ozempic and Mounjaro are not.

These drugs were originally prescribed to patients with Type 2 diabetes as they produce insulin and lower blood sugar. They also release a hormone that slows down digestion and keeps food in a patient's stomach longer. This process suppresses hunger and leads to weight loss — but that can take a toll on the body. 

What are the most typical side effects?

The most common side effects of Ozempic, according to the drug's website, are nausea, stomach pain, constipation, diarrhea and vomiting. 

Novo Nordisk, the maker of Ozempic and Wegovy, told CBS News that the drugs "are a well-established class of medicines, which have demonstrated long-term safety in clinical trials. The most common adverse reactions, as with all GLP-1s, are gastrointestinal related."  

Dr. Meera Shah, an endocrinologist at the Mayo Clinic, said that by far the most common side effect she sees in patients is nausea, followed by abdominal pain, constipation and diarrhea. These side effects can sometimes get better over time but, Shah said, at least 10% of patients who start these drugs have to be taken off of them because the side effects do not improve. 

Constant nausea and abdominal pain is an unpleasant reality. The stomach and brain are so connected that intestinal issues can lead to stress, anxiety and depression — it's what's known as the "gut-brain connection."

"Chronic abdominal pain and unpredictable digestive symptoms such as nausea, diarrhea, fullness or constipation can take a significant toll on your mood and energy levels," Laurie A. Keefer, an academic health psychologist and the Director for Psychobehavioral Research within the Division of Gastroenterology at Mount Sinai, told CBS News.  

Keefer said these symptoms can leave patients feeling isolated, overwhelmed and embarrassed.

"Anxiety about when and where symptoms will occur can also lead to avoidance of social activities, especially ones in which food is the focus, or when bathrooms may not be readily available.  Because the brain and gut are so connected, the emotional symptoms can in turn worsen the gastrointestinal symptoms creating a vicious cycle," she said. 

What are the most extreme side effects?

Other serious side effects of Ozempic include thyroid tumors, pancreatitis, changes in vision, hypoglycemia, gallbladder issues, kidney failure and cancer.

The most severe complications Shah sees in her patients are pancreatitis and gallbladder issues — either can lead to hospitalization.

Though it is not mentioned on Ozempic's website, doctors have reported some patients, their appetites so suppressed, experience malnutrition. Shah said she commonly has to advise patients to take multivitamins or protein supplements in addition to the medication because they aren't getting the nutrients they need from food. 

Model and TikTok star Remi Bader said on the "Not Skinny But Not Fat" podcast earlier this year that a doctor prescribed her Ozempic after she was found to be pre-diabetic and insulin resistant. Weight loss was also a goal. But after going off the medication, Bader gained back the weight she lost while on Ozempic, which subsequently intensified her binge eating disorder. 

Eating disorder experts have stressed that hunger suppressants of any kind can lead to or worsen eating disorders. Eating disorders are not cured by weight loss or weight gain. 

Shah said that the most difficult part of her job today is trying to decipher if patients coming to her for weight-loss drugs are also suffering from eating disorders. Sometimes, patients tell her they've had a history of disordered eating, in which case she recommends they speak with a behavioral psychologist on staff.

What about long-term effects?

It's unclear how these drugs, when prescribed for weight loss, affect the body after years of use. 

"There's a lot of excitement about how good [these drugs] are, and certainly they are very good, but there's a little bit of an unknown in terms of long term," Shah told CBS News. "At some point does your body not respond to it anymore? I don't know."

But weight-loss advocates warn there are long-term health risks of obesity, too. According to the CDC, "people who have overweight or obesity, compared to those with healthy weight, are at increased risk for many serious diseases and health conditions." Those risks include hypertension, coronary heart disease and stroke.

If you or someone you know needs help, call the Anorexia Nervosa & Associated Disorders helpline toll free at 1-888-375-7767.

Editor's note: A previous version of this story misstated Mounjaro's status. It is FDA-approved for diabetes treatment.

In:
• Weight Loss

Cara Korte

CBS News reporter covering climate change and energy.

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