Ozempic or Mounjaro? Semaglutide vs Tirzepatide

Semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro) are two drugs injected subcutaneously once a week that require a physician’s prescription and monitoring. Semaglutide stimulates only the GLP-1 receptor; tirzepatide stimulates both the GIP and GLP-1 receptors. This page summarizes the trials that compared the two drugs directly, why the cardiovascular results cannot be placed side by side, the differences in the Turkish SmPCs (KÜB) and the SGK (Social Security Institution) list, and the shared safety warnings. It contains no price, dosing schedule or sourcing information; the dosing information in the SmPC (KÜB) is product information written for physicians.

Differences between semaglutide and tirzepatide

The grade row is taken from the effect summaries on the two drugs’ guide pages; each grade belongs to that drug’s own trials and does not grade the two drugs against each other.

What the evidence says: head-to-head in type 2 diabetes

SURPASS-2 compared three doses of tirzepatide with semaglutide 1 mg for 40 weeks in 1,879 people with type 2 diabetes taking metformin; the trial is open-label. The HbA1c reduction was 2.01–2.30 points with tirzepatide and 1.86 points with semaglutide; the differences were −0.15, −0.39 and −0.45 points. The weight differences were −1.9, −3.6 and −5.5 kg. ^[4] Nausea was reported in 17–22% in the tirzepatide arms and 18% in the semaglutide arm; serious adverse events were 5–7% in the tirzepatide arms and 3% in the semaglutide arm. The trial was funded by the manufacturer of tirzepatide. ^[4] The comparison does not cover semaglutide doses above 1 mg; 1 mg is the highest weekly dose in the Turkish SmPC (KÜB) of Ozempic. ^[1]

What the evidence says: head-to-head in obesity

SURMOUNT-5 is an open-label phase 3b trial comparing tirzepatide (highest tolerated dose, 10 or 15 mg) with semaglutide (1.7 or 2.4 mg) in 751 adults with obesity without diabetes. At week 72 the mean weight change was −20.2% with tirzepatide and −13.7% with semaglutide; the reduction in waist circumference was 18.4 cm versus 13.0 cm. Participants and physicians knew which drug was given, and the trial was funded by the manufacturer of tirzepatide. ^[5] Because this is a single trial, the evidence grade on this site is C. This finding does not mean that an individual’s response will be similar: the results are averages.

What the evidence says: cardiovascular results

The cardiovascular trials for the two drugs were conducted in different people with different comparators; for this reason the results cannot be placed side by side and turned into the question “which protects more.”

• Semaglutide, SELECT: In 17,604 people aged 45 and over with established cardiovascular disease, BMI of 27 or above and no diabetes, semaglutide 2.4 mg was compared with placebo. Over a mean follow-up of 39.8 months, a major cardiovascular event occurred in 6.5% versus 8.0% (HR 0.80; 95% CI 0.72–0.90). Permanent discontinuation of the drug because of adverse effects was 16.6% versus 8.2%. ^[6] In SUSTAIN 6, summarized in the Turkish SmPC (KÜB) (3,297 people with type 2 diabetes, 104 weeks), the event rate was 6.6% versus 8.9% (HR 0.74); the reduction came mainly from nonfatal stroke and heart attack, with no difference in cardiovascular death. ^[1]
• Tirzepatide, SURPASS-CVOT: In 13,299 patients with type 2 diabetes and atherosclerotic cardiovascular disease, tirzepatide was compared with dulaglutide 1.5 mg, a drug shown to reduce cardiovascular events. Over a median follow-up of about 4 years, the event rate was 12.2% versus 13.1% (HR 0.92; 95.3% CI 0.83–1.01); noninferiority to dulaglutide was shown, and superiority was not shown (P = 0.09). ^[7] The data from this trial are not included in the Turkish SmPC (KÜB) reviewed (March 6, 2026). ^[3]

That is, the cardiovascular data for semaglutide were obtained against placebo and partly in people without diabetes, while those for tirzepatide were obtained against an active drug and in people with diabetes. The two drugs have not been compared in the same trial with cardiovascular events as the endpoint; SURPASS-2 and SURMOUNT-5 measured HbA1c and weight. The grades in the guides also differ (semaglutide B, tirzepatide C).

In Türkiye: licensing, SmPC (KÜB) differences and SGK

The Turkish SmPC (KÜB) of Ozempic has no weight-loss indication; use for weight in someone without diabetes is off-label. The weight-management indication of semaglutide is in a separate product, Wegovy. ^{[1] [2]} For Mounjaro, type 2 diabetes and weight management come under the same product name; the weight indication is for adults with a starting BMI of 30 or above, or 27–30 with at least one weight-related condition such as hypertension, dyslipidemia, obstructive sleep apnea, cardiovascular disease, prediabetes or type 2 diabetes. ^[3] In the Turkish SmPCs (KÜB), personal or family history of medullary thyroid cancer and MEN 2 are contraindications for both drugs. ^{[1] [3]} In all three SmPCs (KÜB), safety and efficacy under 18 years of age have not been established. ^{[1] [2] [3]}

In the SGK (Social Security Institution) EK-4/A List of Reimbursed Medicines published in the Official Gazette on April 8, 2026, there is no product containing semaglutide or tirzepatide; of the products containing GLP-1 receptor agonists, only exenatide and the fixed combination of insulin glargine–lixisenatide are on the list. ^[8] This is a policy document; a medicine’s absence from the SGK list gives no information about its efficacy or safety.

Side effects and shared warnings

The most common side effects of both drugs are gastrointestinal. According to the Ozempic SmPC (KÜB), nausea and diarrhea are very common and vomiting is common; they are mostly mild to moderate in severity and short-lived. ^[1] The Mounjaro SmPC (KÜB) also lists nausea, diarrhea, vomiting and constipation as the most common side effects. ^[3] The serious warnings are shared in both SmPCs (KÜB): acute pancreatitis (the drug is stopped if suspected), gallbladder disease, increased risk of hypoglycemia when combined with a sulfonylurea or insulin, cases of pulmonary aspiration during general anesthesia or deep sedation, and caution in severe gastrointestinal disease. ^{[1] [3]} In SUSTAIN 6, complications of diabetic retinopathy occurred in 3.0% of the semaglutide group and 1.8% of the placebo group; for people with retinopathy using insulin, the SmPC (KÜB) notes this risk separately. ^[1] The full safety list for each drug is in the separate guides.

Counterfeiting is also a shared problem for the two drugs. A letter sent by the Erzurum Provincial Health Directorate to the pharmacists’ chamber (chamber registration date May 20, 2026), citing a TİTCK (Turkish Medicines and Medical Devices Agency) letter dated May 14, 2026, reports that suspected-counterfeit reports for medicines containing GLP-1 receptor agonists have increased markedly, that Ozempic, Saxenda and Wegovy pens and Mounjaro solution for injection carry a high counterfeiting risk, and it stresses that products outside the legal supply chain and those that cannot be recorded in the Medicine Track and Trace System (İlaç Takip Sistemi) should not be held or used. ^[9]

Verdict

The evidence says this: in two head-to-head comparisons (SURPASS-2 in type 2 diabetes, SURMOUNT-5 in obesity), tirzepatide lowered HbA1c and weight more than semaglutide; both trials are open-label and were funded by the manufacturer of tirzepatide. For cardiovascular outcomes, the two drugs were examined in separate trials, in different people and with different comparators; which one protects more is not known. Both carry the safety warnings of the same drug class, are prescription medicines in Türkiye and are not on the SGK list. This page does not recommend a personal choice of drug, a dose or a sourcing route; the treatment decision belongs to the physician.