In this guide

Illustration of two women having a healthcare conversation at a table.

If you have started reading about weight-loss medicines, you have probably encountered several names before getting a clear explanation of how they fit together. Semaglutide. Tirzepatide. Wegovy. Zepbound. Then someone mentions Ozempic or Mounjaro, and the list gets longer.

The names become easier to follow once you separate the active ingredient from the brand. From there, you can look at the questions that matter: how the medicines work, what researchers have found, and what could make one a better fit for your health and daily life.

Two ingredients, several brand names

Semaglutide is the active ingredient in Wegovy. Tirzepatide is the active ingredient in Zepbound. Both brands have approved uses for weight management. Wegovy information, Zepbound information

The same ingredients also appear in medicines approved for type 2 diabetes: semaglutide in Ozempic and tirzepatide in Mounjaro. Sharing an ingredient does not make every branded product's dose or approved uses interchangeable. Ozempic information, Mounjaro information

Semaglutide activates receptors for GLP-1, a hormone involved in blood sugar and appetite regulation. Tirzepatide activates GLP-1 receptors and receptors for another hormone, GIP. Both medicines can reduce food intake through effects on appetite. Semaglutide mechanism, tirzepatide mechanism

That gives researchers a reason to study the medicines separately. Counting hormone targets, by itself, cannot tell you how much weight someone will lose.

What happened when researchers compared them directly?

The SURMOUNT-5 trial randomly assigned 751 adults without type 2 diabetes to weekly injections of tirzepatide or semaglutide for 72 weeks. Treatment reached the highest dose each participant could tolerate within the study's selected doses. Published study abstract

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Treatment studied	Estimated average weight loss at 72 weeks (% of starting weight)
Semaglutide, 1.7 or 2.4 mg weekly	13.7%
Tirzepatide, 10 or 15 mg weekly	20.2%

Tirzepatide produced the larger average reduction: a difference of 6.5 percentage points. The analysis accounted for participants who stopped their assigned treatment; these are estimated group averages, not individual targets or promises. SURMOUNT-5 results, analysis definition

Participants had obesity, or overweight with a weight-related health condition, and both groups received diet and physical-activity counseling. Eli Lilly, which makes tirzepatide, funded the trial. It was open-label, meaning participants and investigators knew which treatment was being used. Study details

The doses matter when interpreting the result. This trial did not compare tirzepatide with oral semaglutide or the newer 7.2 mg Wegovy injection. Those are different regimens included in current Wegovy labeling. The result answers the comparison that was tested. Trial methods, current Wegovy information

SURMOUNT-5 chart: average weight loss at 72 weeks was 13.7 percent with semaglutide and 20.2 percent with tirzepatide. Error bars show 95 percent confidence intervals. Trial regimens and population are stated in the article.

Some differences show up in everyday treatment

Wegovy comes as a weekly injection or a daily tablet. The tablet has specific instructions about taking it on an empty stomach and waiting before eating, drinking, or taking other oral medicines. Zepbound is a weekly injection. A preference for tablets is worth discussing alongside the routine they require. Wegovy information, Zepbound information

Other health conditions can influence the conversation, too. Wegovy has an FDA-approved use to reduce the risk of cardiovascular death, heart attack, and stroke in adults with established cardiovascular disease and either overweight or obesity. FDA cardiovascular approval

Zepbound has an approved use for moderate to severe obstructive sleep apnea in adults with obesity. FDA sleep-apnea approval

Those are examples of why a clinician looks beyond the weight-loss percentage. An approval for a particular condition also does not prove that one medicine is better than the other for every related health outcome.

Side effects belong in the comparison

Both medicines commonly cause nausea, vomiting, diarrhea, and constipation. Serious risks include pancreatitis, gallbladder problems, and kidney injury related to dehydration. Neither should be used by someone with a personal or family history of medullary thyroid cancer or with MEN 2, a rare inherited condition. A previous serious allergic reaction to a product's ingredients also rules that product out. Wegovy safety information, Zepbound safety information

One specific difference concerns birth-control pills. Tirzepatide can reduce the effectiveness of oral hormonal contraceptives. Its label advises switching to a non-oral method or adding a barrier method for four weeks after starting and four weeks after each dose increase. Discuss that plan with the prescriber before treatment. Zepbound contraception guidance

Choosing something you can continue

The decision also involves other medicines, pregnancy plans, cost, and follow-up. Insurance coverage varies, so checking your own plan is more useful than assuming one brand will be affordable. Weight-management treatment may continue long term when it is helping and its risks remain acceptable. NIDDK treatment guidance

Before starting, ask what improvement you and your clinician are aiming for, how side effects will be handled, and what happens if the medicine becomes difficult to obtain or afford. Those answers help turn a comparison between two drugs into a workable plan for your care.