What’s the difference between the GLP-1s on the market?

Ozempic vs. Wegovy, Mounjaro vs. Zepbound, semaglutide vs. tirzepatide—there are a lot of names and terms to keep straight in the GLP-1 world.

And with Goldman Sachs projecting the obesity treatment market will hit $95 billion by 2030, now may be the time to learn the difference.

So if you’re confused about what’s what and who’s who, never fear: Healthcare Brew has put together a handy guide giving a rundown of the key players.

Semaglutide

Semaglutide is the active ingredient in brand-name drugs Ozempic, Wegovy, and Rybelsus. It’s a single-hormone agent that mimics glucagon-like peptide-1, or GLP-1, according to Chika Anekwe, obesity medicine clinical director at Massachusetts General Hospital’s weight center.

GLP-1 is a hormone naturally released by the gut after meals, Anekwe told Healthcare Brew. While the organic version lasts just a few minutes, the medication version is altered to be more stable and last for several days.

The hormone “helps with regulating glucose, and it delays how quickly food empties out of your stomach so you feel fuller for longer,” Anekwe said. “Overall, it’s really beneficial for appetite suppression and blood sugar control and, ultimately, weight loss.”

Semaglutide was developed by Novo Nordisk and received FDA approval in December 2017 under the name Ozempic as a Type 2 diabetes treatment. An alternate version called Rybelsus was approved in September 2019, also as a Type 2 diabetes treatment, and semaglutide received approval for weight loss in June 2021 under the brand name Wegovy.

Tirzepatide

While semaglutide works on a single hormone, tirzepatide—the active ingredient in brand-name drugs Mounjaro and Zepbound—is a dual-hormone medication, according to Anekwe.

That means, in addition to GLP-1, it targets a hormone called glucose-dependent insulinotropic polypeptide, or GIP, which “increases insulin secretion and stimulation, improves fat metabolism and energy expenditure, and helps suppress appetite,” Anekwe said.

Tirzepatide was developed by Eli Lilly and received FDA approval in May 2022 under the name Mounjaro as a Type 2 diabetes treatment. It was later approved in November 2023 as Zepbound for obesity treatment.

Wait, what’s the difference?

You may be wondering why semaglutide and tirzepatide have multiple brand names.

Ozempic, Wegovy, and Rybelsus are all semaglutide. Rybelsus is the standout among the three because it comes in pill form while the other two are injectables—plus, it’s not prescribed as often for weight loss, as it’s currently only approved as a diabetes treatment and isn’t available in doses as strong as Ozempic’s.

But Ozempic and Wegovy are the exact same drug, according to Brian Wojeck, assistant professor of endocrinology at the Yale School of Medicine.

The only difference between the two is what they’re approved to treat (diabetes vs. obesity) and the dosages they come in, Wojeck said. For instance, the max dosage of Ozempic is 2mg while Wegovy’s is 2.4mg.

Mounjaro and Zepbound are also the same but approved to treat different things—even though they come in the same dosages, according to Wojeck.

The difference between semaglutide and tirzepatide, besides the fact that one is a single-hormone and the other is a dual-hormone agonist, is how effective they are, Anekwe said. Studies have shown that tirzepatide is more effective when it comes to weight loss compared to semaglutide.

In clinical trials last year, patients taking the highest dose of semaglutide lost an average of 15% of their body weight compared to 21% on the highest dose of tirzepatide.

Semaglutide and tirzepatide also have treatment indications for conditions aside from obesity and diabetes, Wojeck said. Wegovy is approved to reduce the risk of cardiovascular disease, and Zepbound is approved to treat obstructive sleep apnea.

In their most recent earnings reported in early August, Eli Lilly said Mounjaro and Zepbound brought in a combined $8.6 billion in Q2, and Novo Nordisk reported Ozempic and Wegovy brought in a combined $8 billion for the quarter.

Other options

While semaglutide and tirzepatide are generally the most talked about, they’re not the only GLP-1s on the market. There’s also liraglutide and dulaglutide.

Liraglutide was approved by the FDA under the name Victoza as a Type 2 diabetes treatment in January 2010 and then rebranded as Saxenda for obesity treatment in December 2014. They are both made by Novo Nordisk. Eli Lilly’s dulaglutide was approved in September 2014 under the name Trulicity as a Type 2 diabetes treatment.

The difference between these older GLP-1s versus semaglutide and tirzepatide is that they’re not as effective in terms of weight loss and diabetes, according to Wojeck. They’re also mostly prescribed to treat diabetes instead of obesity, Anekwe added.

What comes next?

There are “a lot of advancements” coming in the world of GLP-1s and obesity treatments in general, Wojeck said.

One is retatrutide, an injectable drug Eli Lilly is developing that’s a triple agonist, meaning that in addition to GLP-1 and GIP, it also targets glucagon. Experts think this means it’ll be even more effective in terms of weight loss, Wojeck said. Eli Lilly is expected to release Phase 3 results on the drug in late 2025 or early 2026.

Plus, Novo Nordisk and Eli Lilly are racing to bring more effective oral GLP-1s to the market, which Wojeck said he believes will “make things easier for a good deal of patients.”

Eli Lilly reported in Q2 2025 earnings on Aug. 7 that its revenue increased 38% compared to the same quarter last year, thanks to growth in Mounjaro and Zepbound sales. Novo Nordisk reported in its Q2 earnings on Aug. 6 that diabetes and obesity treatment drug sales increased 16% YoY.