GLP-1 Weight Loss Drugs: Semaglutide, Tirzepatide, Retatrutide
GLP-1 drugs are peptide medications that copy a hormone your gut already makes to manage appetite and blood sugar. Two of them are FDA-approved for weight loss in the United States: semaglutide and tirzepatide. A third one you’ve probably heard about — retatrutide — is not approved and is still working its way through trials.
So let’s start with what a peptide actually is, then come back — the rest of this page assumes you know these are short chains of amino acids, not a supplement category.
Regulatory status: Semaglutide (Wegovy) and tirzepatide (Zepbound) are FDA-approved for chronic weight management; retatrutide is investigational and not FDA-approved, as of September 2026. This changes — we check it quarterly.
This article is for informational purposes only and isn’t medical advice. Semaglutide and tirzepatide are FDA-approved only for specific uses described below; retatrutide is not FDA-approved and is investigational, as of September 2026. Talk to a licensed healthcare provider before using any peptide, especially one that’s unapproved or compounded. We don’t yet work with a credentialed medical reviewer — see our editorial policy for what that means for this article.
The list of GLP-1 drugs, side by side
| Molecule | Receptor target | Brand name | FDA approval status | Approval date | Route |
|---|---|---|---|---|---|
| Semaglutide | GLP-1 | Wegovy | FDA-approved for chronic weight management | Weight-management approval predates 2024; March 8, 2024 approval added cardiovascular risk reduction | Injection (subcutaneous) |
| Tirzepatide | GIP + GLP-1 | Zepbound | FDA-approved for chronic weight management | November 8, 2023 | Injection (subcutaneous) |
| Retatrutide | GIP + GLP-1 + glucagon | None — no brand name yet | Not FDA-approved; retatrutide is still investigational | None | Injection, investigational only — not commercially available |
No dosing column here on purpose. Dosing is a prescriber’s call, not a comparison-shopping spec.
Head-to-head efficacy isn’t this page’s job either. Those comparisons get their own articles: semaglutide vs. tirzepatide (publishing October 2026) and retatrutide vs. tirzepatide (publishing October 2026).
What GLP-1 is, and how these drugs work
GLP-1 stands for glucagon-like peptide-1. It’s a hormone your small intestine releases after you eat, and it does a few things at once: it signals your pancreas to release insulin, and it signals your brain that you’ve had enough food.
The drugs in this class are called GLP-1 receptor agonists. “Agonist” just means they switch on the same receptor the natural hormone does — they’re built to look enough like GLP-1 that your body responds to them the same way, but they stick around far longer than the hormone your gut makes.
That’s the whole family resemblance. Where these three drugs differ is how many receptors they hit. Semaglutide targets one. Tirzepatide targets two. Retatrutide targets three. More targets isn’t automatically better, but it’s the main reason these compounds behave differently from each other.
Semaglutide (Wegovy)
Semaglutide is the single-target one — it acts on the GLP-1 receptor only. It’s the compound most people mean when they say “the shot,” and under the brand name Wegovy it’s FDA-approved for chronic weight management. The NIH’s NIDDK lists it among the medications approved for long-term weight management use (NIDDK, last reviewed June 2024).
It also has an approval that has nothing directly to do with weight on the scale. On March 8, 2024, FDA approved Wegovy to reduce the risk of serious cardiovascular events in adults with cardiovascular disease who are overweight or have obesity. The trial behind that decision enrolled more than 17,600 people; major adverse cardiovascular events occurred in 6.5% of the semaglutide group versus 8.0% on placebo (FDA, March 2024).
Full mechanism, evidence, and side-effect profile live in our soon-to-be-published semaglutide guide.
Tirzepatide (Zepbound)
Tirzepatide is the dual-target one. It acts on two receptors — GIP and GLP-1 — rather than GLP-1 alone, which is the structural difference people are pointing at when they ask whether it’s “stronger.”
Under the brand name Zepbound, it’s FDA-approved for chronic weight management. FDA approved it on November 8, 2023 (FDA, November 2023). NIDDK also lists it among approved long-term weight-management medications (NIDDK, last reviewed June 2024).
So yes — tirzepatide is a GLP-1 drug, in the sense that GLP-1 is one of the two receptors it targets. People sometimes get told it “isn’t really a GLP-1,” and that’s a misreading of the dual-target design, not a real distinction.
How it stacks up against semaglutide specifically is its own article. The full profile is in our soon-to-be-published tirzepatide guide.
Retatrutide — investigational, not approved
Retatrutide is the one to watch, and it’s also the one you cannot legally get. It’s an Eli Lilly compound that targets three receptors — GIP, GLP-1, and glucagon. It is not FDA-approved for anything, as of September 2026, and NIDDK does not list it among approved weight-management medications.
It has moved deep into late-stage testing. One Phase 3 trial completed on June 16, 2026 (ClinicalTrials.gov NCT05929079), and a second Phase 3 trial in people with obesity and knee osteoarthritis completed November 14, 2025 (ClinicalTrials.gov NCT05931367). Completed trials are not approval — a completed Phase 3 means data exists, not that FDA has reviewed it.
One thing worth being blunt about: FDA stated on September 1, 2026 that retatrutide cannot legally be used in compounding (FDA). If a seller is offering it, that’s the context you need.
Peptides marketed for weight loss that aren’t GLP-1s
Search “weight loss peptides” and you’ll get results that have nothing to do with this class — CJC-1295, AOD-9604, tesamorelin, and others. They work through entirely different pathways, carry entirely different regulatory statuses, and most of them are nowhere near the evidence base semaglutide and tirzepatide have. We’ll cover them separately in a soon-to-be-published guide on peptides marketed for fat loss that aren’t GLP-1s — don’t assume anything on this page transfers to them.
Compounded versus brand-name: what changed
For a couple of years, compounding pharmacies could make semaglutide and tirzepatide because both drugs were in official shortage. That window has closed. FDA declared the tirzepatide shortage resolved on December 19, 2024 and the semaglutide shortage resolved on February 21, 2025, then set end-dates for its enforcement discretion: for tirzepatide, February 18, 2025 (503A pharmacies) and March 19, 2025 (503B outsourcing facilities); for semaglutide, April 22, 2025 and May 22, 2025 (FDA, April 8, 2026).
FDA has also reported adverse events tied to compounded versions: 990 reports for compounded semaglutide and more than 730 for compounded tirzepatide as of May 31, 2026 (FDA, September 1, 2026).
And this is still moving. On April 30, 2026, FDA proposed excluding semaglutide, tirzepatide, and liraglutide from the 503B bulks list; the comment period closed June 29, 2026, and no final determination has been confirmed (FDA). That’s a proposal, not a rule.
If the word “compounded” is doing work you can’t quite define, read what “compounding-eligible” actually means — it is not a synonym for FDA-approved, and the difference matters.
Where to go deeper
- semaglutide — the single-target GLP-1, approved for chronic weight management
- tirzepatide — the dual GIP/GLP-1, approved November 2023
- retatrutide is still investigational — triple-target, Phase 3 complete, not approved
- what “compounding-eligible” actually means — the regulatory distinction people get wrong most often
- peptides marketed for fat loss that aren’t GLP-1s — the non-GLP-1 compounds that show up in the same searches
FAQs About GLP-1 Weight Loss Drugs
Which GLP-1 works best for weight loss?
There are two FDA-approved options for chronic weight management right now — semaglutide (Wegovy) and tirzepatide (Zepbound) — and “best” depends on the person, not on a leaderboard. The structural difference is that tirzepatide acts on two receptors (GIP and GLP-1) while semaglutide acts on one. ⚠ NEEDS MEDICAL REVIEW We break the head-to-head down in our dedicated semaglutide vs. tirzepatide comparison; which one is right for you is a prescriber’s call.
How much weight can you lose on GLP-1 in 3 months?
We’re not going to give you a three-month number, because the trials behind these approvals report results at their own fixed study endpoints — not at 90 days — and individual response varies a lot. Anyone quoting you a precise three-month figure is extrapolating. Ask a licensed prescriber what’s realistic for your situation.
What are the negative side effects of GLP-1?
Every approved GLP-1 drug carries a full FDA-approved label listing its side effects and warnings, and that label — not a blog post — is the authoritative source for your specific medication. One thing worth knowing separately: FDA has logged 990 adverse-event reports for compounded semaglutide and more than 730 for compounded tirzepatide as of May 31, 2026 (FDA, September 1, 2026). Compounded is not the same as FDA-approved. Talk to a licensed healthcare provider before starting or stopping anything.
Are peptides the same as Ozempic?
Not the same thing — Ozempic is a brand name for semaglutide, and semaglutide is one peptide out of thousands. “Peptide” is the whole category (short chains of amino acids); Ozempic is one specific drug in it. For chronic weight management, the FDA-approved semaglutide brand is Wegovy, as of September 2026.
Is tirzepatide a GLP-1?
Yes — with an asterisk. Tirzepatide acts on two receptors, GIP and GLP-1, so it belongs to the GLP-1 class while doing something semaglutide doesn’t. ⚠ NEEDS MEDICAL REVIEW If someone tells you tirzepatide “isn’t really a GLP-1,” they’re misreading the dual-target design.
