Semaglutide vs Tirzepatide: Which Weight Loss Shot Is Right for You?

Semaglutide and tirzepatide are both once-weekly injections for weight loss, but tirzepatide produced more weight loss in head-to-head research. In the SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025, adults with obesity lost an average of 20.2% of their body weight on tirzepatide (Zepbound) compared with 13.7% on semaglutide (Wegovy) after 72 weeks. Semaglutide has a longer track record and an approved heart benefit. Both cause similar stomach side effects. The right choice depends on your goals, your medical history, cost and how your body responds.

If you are an adult with obesity, or overweight with a health problem like high blood pressure, prediabetes or high cholesterol, and you are comparing weight loss medications, this guide covers how semaglutide and tirzepatide work, what clinical trials show, side effects, cost and how to choose.

How semaglutide and tirzepatide work

Both medicines copy gut hormones that your body releases after you eat.

• Semaglutide is a GLP-1 receptor agonist. It slows how fast your stomach empties, lowers appetite and helps the pancreas release insulin when blood sugar is high.
• Tirzepatide is a dual agonist. It acts on GLP-1 receptors and also on receptors for glucose-dependent insulinotropic polypeptide (GIP), a second gut hormone that seems to add to the effect on appetite and blood glucose.

Both slow gastric emptying, so food moves more slowly through the digestive tract. The result for most people is decreased appetite, feeling full sooner and fewer food cravings, which makes it easier to eat less. Both also help the liver regulate sugar production, which is why they were first developed to treat diabetes.

Ozempic and Mounjaro are approved for type 2 diabetes. Wegovy and Zepbound are approved for chronic weight management in adults with obesity, or overweight with at least one weight-related condition.

Semaglutide vs tirzepatide for weight loss: the research

STEP 1 tested semaglutide 2.4 mg weekly in adults with obesity or overweight. After 68 weeks, people lost about 15% of their body weight on average, compared with about 2% on placebo.

SURMOUNT-1 tested tirzepatide. At the highest dose, 15 mg weekly, people lost about 21% of their body weight over 72 weeks.

SURMOUNT-5 compared the two directly. Adults with obesity and without diabetes took the highest dose they could tolerate of either medicine. Tirzepatide produced about 47% more relative weight loss (20.2% vs 13.7%) and a larger drop in waist size. More people on tirzepatide reached 25% weight loss or more.

These are averages. Some people lose much more and some lose less on either drug.

How much weight can you lose?

On average, people in clinical trials lost about 15% of their body weight on semaglutide 2.4 mg and about 20% on the highest dose of tirzepatide, over about a year and a half. For a 220-pound person, that is roughly 33 pounds on semaglutide or 44 pounds on tirzepatide. Results in real life depend on the dose you reach, how long you stay on the medicine, healthy eating, physical activity and sleep.

Cardiovascular risk reduction and other benefits

• Heart: In the SELECT trial, semaglutide 2.4 mg lowered the risk of heart attack, stroke or heart-related death by 20% in adults with established heart disease and overweight or obesity. Wegovy is FDA approved for this cardiovascular risk reduction.
• Kidneys: Ozempic is FDA approved to lower the risk of kidney disease getting worse in adults with type 2 diabetes and chronic kidney disease.
• Liver: Wegovy received FDA approval in 2025 to treat a form of fatty liver disease with liver scarring (MASH).
• Sleep apnea: Zepbound is FDA approved for moderate to severe obstructive sleep apnea in adults with obesity.
• Diabetes: Both medicines lower A1c and improve glycemic control in type 2 diabetes management.

Side effects

The side effects of the two medicines are very similar, because both act on GLP-1. The most common are:

• Nausea, especially in the first weeks and after each dose increase
• Diarrhea or constipation
• Vomiting and acid reflux
• Feeling full quickly or losing interest in food
• Fatigue

Most stomach side effects ease as your body adjusts. Starting low and raising the dose slowly helps.

Less common but serious risks include pancreatitis, gallbladder problems, low blood sugar when combined with insulin or sulfonylureas, and dehydration that can strain the kidneys. Both medicines carry a boxed warning about thyroid C-cell tumors seen in rodents. They are not used in people with a personal or family history of medullary thyroid cancer or multiple endocrine neoplasia type 2 (MEN 2). They are also not used during pregnancy.

Which one should you choose?

Tirzepatide may be the better fit if:

• You want the most weight loss on average
• Semaglutide did not work well enough for you
• You have obstructive sleep apnea

Semaglutide may be the better fit if:

• You have heart disease, since Wegovy is approved to lower the risk of heart attack and stroke
• Your insurance or budget covers it more easily
• You prefer a pill (the Wegovy pill), or you already tolerate it well

Many people do well on either one, as long as the medicine is paired with healthy lifestyle changes. The bigger factors for long-term success are often protein intake, strength training to protect muscle, sleep and a plan for what happens when the dose changes or stops.

Other weight loss drugs

Semaglutide and tirzepatide are among the most effective weight loss drugs available, but they are not the only options. Other FDA approved weight loss medications include liraglutide (Saxenda, a daily GLP-1 shot), phentermine-topiramate (Qsymia), naltrexone-bupropion (Contrave) and orlistat. They usually produce less weight loss but may fit some people better because of cost, other medications or health problems.

Cost and insurance coverage

Insurance coverage for weight loss medicines varies widely. Many insurance plans do not cover them for weight loss alone, and list prices change often. Both manufacturers now sell self-pay options directly. Ask your provider and your insurer what applies to you before you start.

Compounded versions of semaglutide and tirzepatide are not FDA-approved. After the national shortages of both drugs ended in 2024 and 2025, the FDA limited when pharmacies can make copies. Ask exactly what product you are getting and where it comes from.

What happens when you stop

Weight often comes back after stopping either medicine. In follow-up studies, people regained a large share of the weight they had lost within a year of stopping. Planning for maintenance from the start, with nutrition, strength training and sometimes a lower maintenance dose, gives you the best chance of keeping results.

Medical weight loss in Owasso

At Pathway Health & Beauty, Tia Christ, APRN-CNP, prescribes semaglutide and tirzepatide when they fit your health history and labs, as part of a full medical weight loss plan with nutrition, strength and sleep support. Many check-ins can be done by telehealth anywhere in Oklahoma. Call or text 918-973-4575 for a free discovery call.