Short answer: Tirzepatide (sold for weight loss as Zepbound) and semaglutide (sold for weight loss as Wegovy) are both FDA-approved prescription medicines for chronic weight management. Semaglutide acts on one gut hormone receptor (GLP-1). Tirzepatide acts on two (GIP and GLP-1). In one head-to-head trial, tirzepatide led to more weight loss on average. Both carry a boxed warning about thyroid C-cell tumors.
Both medicines copy hormones your gut releases after you eat. These hormones help control blood sugar, slow how fast the stomach empties and signal fullness to the brain. For many people, that means smaller appetites and fewer cravings.
Researchers are still learning why the second receptor seems to add weight loss for many people.
The most direct comparison comes from SURMOUNT-5, a 72-week trial published in the New England Journal of Medicine in 2025. About 750 adults with obesity and without diabetes took the highest dose they could tolerate of either tirzepatide or semaglutide.
The earlier placebo-controlled trials point the same way. In STEP 1, adults on semaglutide 2.4 mg lost about 15% of their weight over 68 weeks. In SURMOUNT-1, adults on the highest tirzepatide dose lost about 21% over 72 weeks. All of these people also made diet and activity changes.
These are averages. Results vary from person to person, and not everyone is a candidate for either medicine.
Zepbound starts at 2.5 mg once a week for four weeks. The dose can go up by 2.5 mg every four weeks or longer, to a maintenance dose of 5, 10 or 15 mg a week. It comes in single-dose pens, single-dose vials and a multi-dose pen.
Wegovy injection starts at 0.25 mg once a week and steps up every four weeks to 1.7 mg or 2.4 mg by about week 17. For adults who tolerate 2.4 mg and need more weight loss, the label now allows a higher dose of up to 7.2 mg weekly.
Wegovy tablets are taken once a day, starting at 1.5 mg and rising each month to 25 mg. The tablet has strict rules: take it in the morning on an empty stomach with no more than 4 ounces of plain water, and wait at least 30 minutes before eating, drinking or taking other pills.
Going up slowly helps the stomach adjust.
The common side effects are similar for both. They are mostly in the gut and are most likely when starting or raising the dose:
In SURMOUNT-5, stomach side effects led about 2.7% of people on tirzepatide and 5.6% on semaglutide to stop treatment.
Serious risks listed on both labels include:
The Wegovy label also lists a faster heart rate.
Obesity is a long-term condition. In a follow-up of the STEP 1 trial, people who stopped semaglutide regained about two-thirds of the weight they had lost within a year. In SURMOUNT-4, people switched from tirzepatide to a placebo regained a large share of their weight, while those who stayed on it kept losing. These medicines are meant to be used long-term along with eating and activity changes, and that plan should be made with your clinician.
Yes. FDA approved a once-daily pill, Foundayo (orforglipron), in April 2026 for adults with obesity or overweight with a related health problem. Older medicines exist too.
Is tirzepatide stronger than semaglutide? In the SURMOUNT-5 trial, people on tirzepatide lost more weight on average (20.2% vs 13.7% over 72 weeks). That does not mean it is the right choice for everyone. Side effects, health history and coverage matter too.
Is Zepbound the same as Mounjaro? Both contain tirzepatide. Zepbound is approved for weight management and sleep apnea. Mounjaro is approved for type 2 diabetes.
Is Wegovy the same as Ozempic? Both contain semaglutide. Wegovy is approved for weight management and heart risk reduction. Ozempic is approved for type 2 diabetes. Doses differ.
Can I switch from semaglutide to tirzepatide? Some people do, under a clinician's care. The labels say not to take them together.
What is the boxed warning on GLP-1 medicines? It is FDA's strongest warning. For Zepbound and Wegovy, it says the medicines caused thyroid C-cell tumors in rodents, and it is unknown whether they do in people. Tell your clinician about any lump in your neck, trouble swallowing, hoarseness or shortness of breath.
Wondering if a GLP-1 medicine is right for you? Dr. Vargas can review your health history and talk through FDA-approved options, their risks and what else may help.
Book a visit or call (210) 903-1030 In-clinic in San Antonio • Telehealth for women located in Texas Yaso Wellness Health Clinic, 1907 Goliad Rd, San Antonio, TX 78223
Leticia Vargas, MD, OB/GYN. About Dr. Vargas
Education only, not medical advice or a diagnosis. In an emergency, call 911.
