> APPROVALS · STUDY RESULTS · SIDE EFFECTS
What Tirzepatide may change, and what can go wrong
Tirzepatide is a weekly medicine that follows the work of two hormones that come from your gut; doctors call one GLP-1. In May 2022 came the first FDA approval, for type 2 diabetes, with long-term weight care following in November 2023. This isn't a clinic.
> What Tirzepatide can change for you
What may Tirzepatide do? It can lower your blood sugar and help you lose weight. In May 2022, the FDA approved it for type 2 diabetes. In November 2023 came approval for weight care. A later approved use covered sleep apnea for adults living with obesity.
The shot follows two hormones that your gut releases after meals. The best-known one is GLP-1. These hormones help steady sugar levels and ease hunger. Tirzepatide adds the action of another hormone to GLP-1, which may help explain its effects. That idea isn't firm proof.
The largest weight study ran for 72 weeks. At the highest dose, people lost an average of 20.9% of their starting weight [1]. In direct tests, people had larger drops in weight and blood sugar with Tirzepatide than with medicine copying GLP-1 alone [2] [3].
What can go wrong? Nausea, loose stools, vomiting, and constipation can begin during dose increases. Reviews saw more illness affecting the gallbladder or the tubes carrying bile [4]. Rats and mice formed a rare cancer of the thyroid after getting drugs of this kind [5]. Human risk remains unknown. Studies also found muscle loss and loss of other tissue besides fat [6]. Read what people report, both good and bad.
What keeps Tirzepatide working all week
What is Tirzepatide? It is a lab-made peptide, meaning a small chain made of protein pieces. It is a 39-amino-acid chain, but that count doesn't guide your care. Tirzepatide copies the work of two hormones that the gut releases after food. One is called GLP-1 in medical papers.
One added fat-like part lets the drug attach to albumin, which is a common protein in your blood. This helps Tirzepatide leave your body slowly. About half is gone after 5 days [7]. That slow exit makes weekly use possible.
Cell tests compared the drug's GLP-1 action with its other hormone action. Tirzepatide acted more strongly like the other hormone [8]. Scientists think its GLP-1 balance may affect insulin and weight. This GLP-1 work only suggests why the drug works. It can't tell your own outcome.
What Tirzepatide weight loss looked like in studies
How much weight did people lose? A study called SURMOUNT-1 followed 2539 adults with obesity; none of them had type 2 diabetes. They took weekly Tirzepatide for 72 weeks. Average loss was 15.0% at 5 mg and 19.5% at 10 mg. At 15 mg, average loss was 20.9%. The placebo group, given shots with no drug, lost 3.1% [1].
At the top dose, the group average was 20.9%. You may see a very different result.
Tirzepatide may ease hunger, so people eat less. It copies the work of two gut hormones, including GLP-1, that guide blood sugar and the sense of fullness. People still lost weight when they had no stomach trouble [9]. Nausea wasn't the whole reason for the loss.
A second study, called SURMOUNT-5, followed 751 adults with obesity for 72 weeks. Using the largest dose each could handle, average loss was 20.2%, compared with 13.7% on another shot acting like GLP-1 [3].
What Tirzepatide vs semaglutide changed in studies
Two large studies give the best direct comparison. For 40 weeks, SURPASS-2 tracked 1879 adults with type 2 diabetes. They took weekly Tirzepatide at 5, 10, or 15 mg. Others took semaglutide, another weekly prescription shot, at 1 mg.
The next blood test reflected the prior few months of blood sugar. Tirzepatide lowered that result by 2.01, 2.24, and 2.30 points. The drop with semaglutide was 1.86 points. Tirzepatide also led to 1.9, 3.6, and 5.5 kg more weight loss [2].
SURMOUNT-5 finished in 2025 and compared the shots for obesity. After 72 weeks, average loss was 20.2% with Tirzepatide and 13.7% with the other shot. That other medicine copies the work of the gut hormone GLP-1. The difference was 6.5 points [3].
Both shots often upset the stomach. One review compared Tirzepatide with dulaglutide, another diabetes shot taken weekly. Stopping due to side effects was 32% more likely with Tirzepatide [10]. The review gives no plain count here, so that figure can't tell you how many stopped.
What Tirzepatide results mean for you
What did the largest studies find? With type 2 diabetes and obesity, higher doses led to greater falls in body weight and sugar readings. Tirzepatide also did more than medicine that copies GLP-1, one gut hormone. The drug adds a second action to GLP-1.
These were phase 3 studies, the big last tests before approval:
- [+] SURMOUNT-1 followed 2539 people for 72 weeks. At 15 mg, people lost an average of 20.9%. With placebo, an injection without medicine, average loss was 3.1% [1].
- [+] SURPASS-2 followed 1879 people for 40 weeks. At 15 mg, Tirzepatide lowered the blood test that reflects sugar over the last few months by 2.30 points. The other medicine lowered it by 1.86 points [2].
- [+] SURMOUNT-5 followed 751 people for 72 weeks. People lost an average of 20.2% with Tirzepatide and 13.7% with the other shot [3].
- [note] Heart disease, sleep apnea, and liver scars were covered in other studies [11] [12] [13].
Your result may not match a group average. Read about tirzepatide side effects and tirzepatide muscle loss. You can check every paper under Tirzepatide references.