Tirzepatide vs Semaglutide for Weight Loss: How They Compare

Tirzepatide and semaglutide are the two compounded treatments people talk about most. Both are weekly injections. Both reduce appetite and support weight loss. They are not the same molecule, so the result is different.

How each one works

Semaglutide is a GLP-1 receptor agonist. It mimics a gut hormone your body releases after you eat. That hormone slows digestion and signals fullness to the brain, so you get full a lot faster! (NIH).

Tirzepatide does the same thing through GLP-1, then adds a second target called GIP. Acting on both pathways gives the brain and gut a stronger fullness signal. That dual action is why tirzepatide is often described as the more powerful of the two. It helps decrease weight faster. (NIH).

Neither one is a stimulant. Neither one forces your body to do anything. They work with the current conditions your body is under.

What the head-to-head data shows

For a long time the two were only compared across separate studies. Then a trial put them against each other directly.

In a 72-week head-to-head study, people on tirzepatide lost about 20.2 percent of their body weight. People on semaglutide lost about 13.7 percent (NEJM, 2025). Both results are meaningful. Tirzepatide came out ahead with 6.5% more body fat loss.

Your result depends on dose, consistency, and habits like diet and sleep. Some people do very well on semaglutide. The trial tells you the typical pattern, not your exact outcome.

Side effects are similar

Both treatments share the same main side effects, and most are digestive. Nausea, reduced appetite, constipation, and occasional reflux are the common ones. They tend to show up early and fade as your body adjusts (NIH).

The standard way to limit them is start with a smaller dose then slowly increase. You start low. The dose steps up over weeks. A provider sets the schedule and adjusts it if side effects get in the way.

Which one is right for you

That is a clinical decision, not a checkout choice. A licensed provider reviews your health history, current medications, and goals before prescribing either one. Some people are better suited to one molecule than the other.

At PepHaūs, both are compounded by a U.S.-licensed pharmacy and prescribed after an online visit. Compounded medications are not FDA-approved, and a provider has to decide the treatment is appropriate for you. Price is flat and cash-pay, with no insurance billing in the way.

Tirzepatide tends to produce more weight loss on average, semaglutide is well studied and effective, and the right fit is the one your provider lands on for your body and goals!

FAQ

Is tirzepatide always better than semaglutide?

On average it produced more weight loss in a direct trial. That does not make it the right choice for everyone. Health history and tolerance matter, and your provider will tell you which is best!

Can I switch between them?

Sometimes. A provider may adjust your treatment based on results and how you tolerate it. Any change will be a good question for them.

How fast will I see results?

Appetite often shifts in the first few weeks. Weight changes are gradual and build over months. Consistency matters more than speed.

Are these the same as the brand-name pens?

They use the same active compounds, tirzepatide and semaglutide, prepared by a compounding pharmacy. They are dispensed for human use after a provider's review.