Tirzepatide is currently approved as a treatment for type 2 diabetes and is expected to be approved as a weight loss treatment.
Tirzepatide is linked to fewer side effects than Ozempic.
Ozempic is linked to side effects such as thyroid cancer, gallbladder disease, and ileus.
The United States Food and Drug Administration (FDA) first approved semaglutide, sold under the brand name Wegovy, as a weight management treatment in 2021. Since then, the drug has grabbed headlines for both its results and its association with serious side effects. Now, trials of tirzepatide—a drug that is currently FDA-approved as a treatment for type 2 diabetes—indicate that it has the potential to be a weight loss treatment with lower risks of side effects.
Ozempic is linked to significant weight loss for some users. The medication was initially approved in 2017 as a treatment for type 2 diabetes. The medical community and the public noticed its effects on weight before its FDA approval for weight loss, generating buzz and demand. In the late 2010s, the drug was prescribed to people who did not have diabetes as an off-label weight loss treatment.
In clinical trials, Ozempic users lost an average of over 10% of their body weight at six months. A 2022 study found that this was closely replicated in clinical settings. These results have led to high demand. In July 2023, American physicians wrote about 94,000 prescriptions per week for Wegovy compared with about 62,000 for Ozempic. Pharmacies in the US frequently experience shortages of these medications.
However, the side effects linked to Ozempic are significant. While most people who take Ozempic experience no side effects, those who do experience notable effects. Serious side effects include possible thyroid tumors, including cancer, pancreatitis, gallbladder problems, hypoglycemia, and serious allergic reactions.
Some side effects and risks of Ozempic are still being evaluated and monitored. In late September 2023, the FDA added a new side effect warning for ileus to the Ozempic label. Additionally, in July 2023, the European Medicines Agency began evaluating the link between Ozempic and an increased risk of suicidal ideation and thoughts of self-harm. In the US, the label for Wegovy contains a warning for an increased risk of suicidal thoughts, but the label for Ozempic does not. 
These side effects can make some people understandably wary about taking Ozempic, despite its potential weight loss benefits. Fortunately, it’s likely that additional treatment options are on the way. On October 6, 2022, tirzepatide’s manufacturer, pharmaceutical company Eli Lilly, announced that it had received FDA Fast Track designation for tirzepatide.
In trials, over 85% of participants who received once-weekly subcutaneous tirzepatide for 72 weeks lost more than 5% of their body weight, with an average weight reduction of around 20%. Participants were able to sustain their weight loss over 72 weeks.
Tirzepatide is linked to fewer side effects than Ozempic. Most side effects include minor and passing gastrointestinal effects, such as nausea or diarrhea. Like Ozempic, tirzepatide is linked to a risk of pancreatitis and hypoglycemia, but these risks are considered low. Other possible risks include sinus tachycardia, acute kidney injury, and reduced efficacy of oral hormonal contraceptives. There are also reports of cholelithiasis and cholecystitis; however, increases in cases among those in a placebo group was less than 0.6%, and causation was unclear.
Diabetes medications and weight loss
The Centers for Disease Control and Prevention (CDC) reports that the US adult obesity prevalence is nearly 42%. The weight loss industry is a large part of US culture, and headlines promising diet plans, tips, and tricks have been commonplace for decades. However, few medically approved solutions exist beyond healthy eating and physical activity. Bariatric surgery is an option for some people with obesity, but it can have its significant drawbacks.
Until recently, weight loss drugs have been dangerous, ineffective, or a combination thereof. For instance, drugs such as sibutramine, fenfluramine, and phentermine have all been linked to serious heart risks. The discovery that certain diabetes medications could be used to help manage weight was an accident.
Medications such as Ozempic and tirzepatide are made with the hormone GLP-1. GLP-1 regulates blood sugar by acting on the insulin-producing cells of the pancreas, and only when blood sugar rises too high. During trials to find the correct way to use GLP-1 and to keep it in the body, researchers noted an unintended side effect: Rats implanted with tumors of pancreas cells that produced high levels of GLP-1 nearly stopped eating. This discovery eventually led to human trials and to the revelation that GLP-1 could be used for weight loss. 
While knowledge of these medications is still developing, they’ve already become the treatment option of choice for many people. As director of the Weill Cornell Medicine Comprehensive Weight Control Center in New York, Louis Aronne commented while presenting the results of Eli Lilly’s SURMOUNT-4 trial results for tirzepatide at the European Association for the Study of Diabetes conference in Hamburg, Germany:
“It’s really incredible where we are now in the treatment of obesity compared to where we were as recently as five or 10 years ago. We’re in a bit of a revolution, in case you haven’t noticed, in the treatment of cardiometabolic disease with semaglutide and now tirzepatide.”