Semaglutide vs Tirzepatide: One Receptor or Two

GLP-1 is a hormone the gut releases after eating. It is involved in insulin release, in how quickly the stomach empties and in the sense of fullness. Semaglutide engages the GLP-1 receptor, and the Wegovy label describes it as a GLP-1 receptor agonist.

Tirzepatide engages the GLP-1 receptor too, and adds a second: the receptor for GIP, another gut hormone released after meals that is involved in the insulin response. The Zepbound label describes tirzepatide as a GIP receptor and GLP-1 receptor agonist. MedlinePlus places both in the same class, incretin mimetics.

"Dual" describes the mechanism. It is not a statement about results. Whether the second pathway matters for you is a judgment your clinician makes from your history, labs and response, and the tirzepatide injection page explains what GIP adds in more depth.

At ACT 2 both are available as a once-weekly injection under the skin, with the regimen set and adjusted by your clinician over time, and both are also offered as a daily capsule. The branded labels describe the same weekly rhythm for their injections: the Wegovy label says to inject on the same day each week, at any time of day, with or without meals, and the Zepbound label likewise sets a weekly injection with the dose increased in steps.

That stepwise start is common to both. The dose is raised gradually over the first months, mainly so the stomach has time to adjust. The oral vs injectable semaglutide comparison covers the capsule-or-injection question separately.

The monitoring overlaps far more than it differs, because the warnings on the two branded labels are largely shared.

• Thyroid. Both the Wegovy and Zepbound labels carry a boxed warning about thyroid C-cell tumors seen in rodents, and both are contraindicated in people with a personal or family history of medullary thyroid carcinoma or with MEN 2.
• Digestion. Gastrointestinal effects are the commonest problem with both, and both labels warn about pancreatitis and gallbladder disease.
• Blood sugar. Both labels advise extra care alongside insulin or a sulfonylurea, because the combination raises the risk of low blood sugar.
• Oral medicines. Both slow stomach emptying, which can affect how other tablets are absorbed. The Zepbound label adds a specific instruction for people using oral hormonal contraceptives: switch to a non-oral method, or add a barrier method, for a period after starting and after each dose increase.

At ACT 2 the program starts from a baseline lab panel and continues with ongoing clinical review. The GLP-1 side effects FAQ covers what to expect week to week.

Semaglutide is FDA-approved as Wegovy for weight management and as Ozempic for type 2 diabetes. Tirzepatide is FDA-approved as Zepbound for weight management and as Mounjaro for type 2 diabetes.

The semaglutide and tirzepatide prescribed through ACT 2 are compounded by a licensed pharmacy. They are not FDA-approved, and they are not the same as, equivalent to or interchangeable with Wegovy, Ozempic, Zepbound or Mounjaro. The FDA states that it does not review compounded drugs for safety, effectiveness or quality before they are marketed, and it has published its concerns about unapproved GLP-1 drugs. The compounded semaglutide vs Wegovy and compounded tirzepatide vs Zepbound pages set out what that means.

What the branded trials show, and for which product. The Wegovy label reports placebo-controlled trials in which adults taking Wegovy injection lost more weight on average than those taking placebo. The Zepbound label reports placebo-controlled trials in which adults taking Zepbound lost more weight on average than those taking placebo. Those results belong to the branded products they were run on, and they do not carry across to a compounded preparation.

Semaglutide tends to suit adults for whom a single-pathway GLP-1 option fits the clinical picture. Tirzepatide tends to suit adults for whom a dual-pathway option fits the clinical picture. Neither is "better" as a general matter. Individual response varies, and a person who does not tolerate one is sometimes moved to the other.

Both injections are priced the same at every dose. Compounded semaglutide is $299 a month and compounded tirzepatide is $399 a month, so tirzepatide costs more. Both come in 3- and 6-month packages that lower the monthly figure. Lab work is priced separately. That is a comparison of price only, not of effectiveness. Packages, a year's total and the insurance question are covered in full on the semaglutide cost and tirzepatide cost pages.

A GLP-1 is not the right tool for everyone. A personal or family history of medullary thyroid carcinoma or MEN 2 rules out both. Where insulin resistance rather than weight is the main problem, metformin may be the conversation instead. Where weight change is entangled with the menopause transition or thyroid function, those come first. And if your insurance covers a branded product, the Weight Loss Program Membership provides the clinical care around it.