GLP-1 medications are a class of drugs that activate the GLP-1 hormone receptor to slow stomach emptying and curb appetite, and the class now includes drugs that activate additional receptors on top of GLP-1. Semaglutide (sold as Ozempic for type 2 diabetes and Wegovy for weight loss) activates GLP-1 alone. Tirzepatide (sold as Mounjaro and Zepbound) is a dual GIP and GLP-1 receptor agonist. Retatrutide is a triple GIP, GLP-1 and glucagon receptor agonist that is still investigational and cannot legally be bought or prescribed. All three are commonly discussed together because all three activate the GLP-1 receptor as at least one of their targets.
Below: what activating the GLP-1 receptor actually does in the body, how the three receptor classes compare in the evidence, a side-by-side table of which drug belongs to which class and its approval status, what side effects the class shares, who is and isn’t a candidate, why compounded GLP-1 is not the same thing as an FDA-approved product, and how to actually get one prescribed today.
Key takeaways
What does GLP-1 stand for?
GLP-1 stands for glucagon-like peptide-1, the hormone receptor that every drug in this class activates. Semaglutide activates it alone; tirzepatide and retatrutide activate it alongside additional receptors.
What are the three types of GLP-1-class medications?
A single GLP-1 receptor agonist (semaglutide), a dual GIP and GLP-1 receptor agonist (tirzepatide), and a triple GIP, GLP-1 and glucagon receptor agonist (retatrutide, investigational only). Each activates one more receptor than the last.
Are Ozempic and Wegovy GLP-1 medications?
Yes. Both are brand names for semaglutide, a GLP-1 receptor agonist. Ozempic is FDA-approved for type 2 diabetes; Wegovy is FDA-approved for weight loss.
Is tirzepatide a GLP-1 medication?
Yes, in the sense that it activates the GLP-1 receptor, but it is more precisely a dual GIP and GLP-1 receptor agonist since it also activates a second receptor, GIP. It is sold as Mounjaro and Zepbound, both FDA-approved.
Can you buy a GLP-1 medication without a prescription?
No. Every FDA-approved GLP-1 medication requires a licensed prescriber’s evaluation. Retatrutide, the investigational triple agonist, cannot legally be bought or prescribed at all.
Is compounded GLP-1 the same as an FDA-approved GLP-1 medication?
No. A compounded preparation contains the same active ingredient, but it is not itself an FDA-approved finished product, even when the compounding pharmacy is properly registered. That distinction holds regardless of which GLP-1-class drug is being compounded.
What activating GLP-1 (and its neighbors) actually does
Every drug in this class activates the GLP-1 receptor, and that single receptor is responsible for most of what “GLP-1 medication” means in practice. Stimulating it slows stomach emptying, which keeps food in the stomach longer and extends the feeling of fullness after a meal, and it acts on appetite-signaling pathways in the brain that reduce hunger between meals. That combination, slower emptying plus reduced appetite signaling, is what curbs appetite and also helps steady blood sugar, which is why the class serves both a weight-loss indication and a type 2 diabetes indication depending on the drug and dose.
The class splits into three tiers by how many receptors a given drug activates. Semaglutide activates GLP-1 alone. Tirzepatide adds a second receptor, GIP, which works through a separate pathway involved in insulin response and its own effect on appetite; that extra receptor is the leading explanation for why tirzepatide has outperformed semaglutide in clinical measurement. Retatrutide adds a third, glucagon, on top of GIP and GLP-1, making it a triple agonist. Retatrutide remains investigational: it has not completed the FDA approval process and cannot legally be bought or prescribed for weight loss.
What the evidence shows across the class
The clearest evidence comparing two GLP-1-class drugs head to head is SURMOUNT-5, the only randomised trial that has directly compared a single GLP-1 agonist against a dual GIP and GLP-1 agonist. Aronne LJ, Horn DB, le Roux CW, Ho W and colleagues published it in the New England Journal of Medicine on 3 July 2025 (DOI 10.1056/NEJMoa2416394, PMID 40353578, registered as ClinicalTrials.gov NCT05822830). It randomised 751 adults with obesity but without type 2 diabetes, 1:1, to the maximum tolerated dose of tirzepatide (10 or 15 mg) or semaglutide (1.7 or 2.4 mg), both once weekly by subcutaneous injection, for 72 weeks. Tirzepatide, the dual agonist, produced −20.2% mean body weight change (95% CI −21.4 to −19.1); semaglutide, the single agonist, produced −13.7% (95% CI −14.9 to −12.6), P<0.001. Read that gap alongside two caveats: SURMOUNT-5 was open-label, so participants and investigators both knew which drug each person was taking, and it was funded by Eli Lilly, which manufactures tirzepatide.
Retatrutide, the triple agonist, has never been tested against either approved drug in a head-to-head trial. What exists instead is its own separate phase 2 trial: Jastreboff AM, Kaplan LM, Frías JP and colleagues, published in the New England Journal of Medicine in 2023 (389(6):514-526, DOI 10.1056/NEJMoa2301972, PMID 37366315, registered as NCT04881760), a double-blind, placebo-controlled trial of 338 adults over 48 weeks. Retatrutide’s least-squares mean weight change at the 12 mg dose was −24.2%, against −2.1% on placebo. That number is larger than either SURMOUNT-5 figure, but it comes from a trial with a different design, a different duration and a different patient population, not from a comparison against tirzepatide or semaglutide. Lining it up next to SURMOUNT-5’s numbers and calling it a three-way ranking would misrepresent what either trial actually measured.
| GLP-1 receptor agonist | Dual GIP and GLP-1 receptor agonist | Triple GIP, GLP-1 and glucagon receptor agonist | |
|---|---|---|---|
| Drug | Semaglutide | Tirzepatide | Retatrutide |
| Brand names | Ozempic (type 2 diabetes), Wegovy (weight loss) | Mounjaro (type 2 diabetes), Zepbound (weight loss) | None; not an approved product |
| FDA approval status | FDA-approved | FDA-approved | Investigational; cannot be legally bought or prescribed |
| Weight-loss evidence | −13.7% at 72 weeks, head to head vs tirzepatide (SURMOUNT-5) | −20.2% at 72 weeks, head to head vs semaglutide (SURMOUNT-5) | −24.2% at 12 mg, 48 weeks, its own separate placebo-controlled trial; no head-to-head exists |
Side effects across the class
The most common adverse events reported in SURMOUNT-5 were gastrointestinal in both the semaglutide and tirzepatide groups, mostly mild to moderate and occurring primarily during dose escalation (Aronne LJ, Horn DB, le Roux CW, Ho W, et al., NEJM, 2025). That pattern tracks with the mechanism shared across the whole class: every drug here affects the digestive system through at least the GLP-1 receptor, so a stronger version of that signal is generally felt there first as a dose is stepped up, regardless of how many additional receptors a given drug also activates.
No incidence figures for specific side effects, broken down by symptom or by dose, are published in the SURMOUNT-5 material this page draws from, so none are stated here. Treat any specific side-effect percentage you see elsewhere attributed to that trial with the same scrutiny this page applies to its own numbers, and check it against the source (DOI 10.1056/NEJMoa2416394).
Who a GLP-1 medication is for, and who it isn’t
An FDA-approved GLP-1-class medication, semaglutide or tirzepatide, is for someone who has been evaluated by a licensed prescriber and found to be an appropriate candidate for a type 2 diabetes or weight-loss indication. That evaluation, not this page, is what determines whether the single-receptor or dual-receptor drug is the better starting point for a given person’s health history. Our semaglutide vs tirzepatide comparison lays out that specific trade-off, including where tirzepatide’s SURMOUNT-5 result and semaglutide’s longer track record each carry weight.
Retatrutide is not an option for anyone right now, regardless of how promising its own phase 2 number looks: it is investigational, has not completed the FDA approval process, and cannot legally be bought or prescribed for weight loss. Anyone offered retatrutide outside of a registered clinical trial should treat that as a red flag, not an opportunity, since no verified purity or dosing standard backs a product sold that way.
How to actually get one prescribed today
Semaglutide and tirzepatide are both FDA-approved and available today from a licensed prescriber after a medical evaluation; retatrutide is not an option at all outside a clinical trial. The providers below evaluate eligibility and prescribe compounded semaglutide or compounded tirzepatide, the same two active ingredients discussed on this page. It is worth stating plainly here, since this is the natural place for it: a compounded GLP-1 preparation carries the same active ingredient as the FDA-approved brand-name product, but the compounded preparation itself is not an FDA-approved finished product, even when the compounding pharmacy is properly registered with the FDA. Registration of the pharmacy is not the same thing as approval of the specific product it compounds.
These providers prescribe tirzepatide and semaglutide, which are FDA-approved. We may earn a commission, and it never changes your price.
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#1
TrimRxPersonalized programs, US pharmacies
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#2
Joi & BlokesHis & hers compounded GLP-1s
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#3
ReadyRxFast approvals on weight-loss meds
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The table below scores all five providers this site reviews against the same published rubric, so you can see how each one’s semaglutide and tirzepatide pricing and track record compare before you pick one. Read our full TrimRx review for the most detailed look at one of them.
| # | Provider | Our score | Semaglutide | Tirzepatide | Worth knowing |
|---|---|---|---|---|---|
| 1 | TrimRx | 3.0/5 | from $199/mo | from $349/mo | Price stays flat as the dose escalates. |
| 2 | Joi & Blokes | 2.0/5 | $199/mo, billed quarterly | $299/mo, billed quarterly | First payment is $497 (semaglutide) or $747 (tirzepatide). |
| 3 | ReadyRx | 2.0/5 | $299/mo, or $249/mo prepaid | $399/mo | Refund if you have not lost 5% of baseline weight by 28 weeks. |
| 4 | AltRx | 0.5/5 | $89/mo promotional, $199/mo standard | $149/mo | BBB rates it F for failure to respond to 37 complaints. |
| 5 | Zevay | 0.0/5 | $149/mo | $187/mo | No BBB or Trustpilot profile found as of 16 July 2026. |
Scores are computed from our published rubric, shown in full on each review. Prices verified 16 July 2026: confirm your current price with the provider before you pay.
Sources
Aronne LJ, Horn DB, le Roux CW, Ho W, et al. “Tirzepatide as Compared with Semaglutide for the Treatment of Obesity.” New England Journal of Medicine, 3 July 2025. DOI: 10.1056/NEJMoa2416394. PMID 40353578. Registered as ClinicalTrials.gov NCT05822830. This is the primary source for every SURMOUNT-5 figure on this page.
Jastreboff AM, Kaplan LM, Frías JP, et al. “Triple-Hormone-Receptor Agonist Retatrutide for Obesity, A Phase 2 Trial.” New England Journal of Medicine, 2023;389(6):514-526. DOI: 10.1056/NEJMoa2301972. PMID 37366315. Registered as ClinicalTrials.gov NCT04881760. This is the source for the retatrutide figure referenced above, given for context only, not as a head-to-head comparison.
GLP-1 medications: frequently asked questions
What is a GLP-1 medication?
A GLP-1 medication is a drug that activates the GLP-1 hormone receptor to slow stomach emptying and reduce appetite. Semaglutide (Ozempic, Wegovy) activates GLP-1 alone. Tirzepatide (Mounjaro, Zepbound) and investigational retatrutide activate GLP-1 alongside additional receptors, GIP and, for retatrutide, glucagon as well.
What is the strongest GLP-1 medication?
Among FDA-approved options, tirzepatide produced more weight loss than semaglutide in the only head-to-head trial that exists, 20.2% versus 13.7% at 72 weeks (Aronne LJ, Horn DB, le Roux CW, Ho W, et al., NEJM, 2025). Retatrutide’s own separate trial reported a larger number, −24.2% at 12 mg, but it has never been tested against either approved drug and remains investigational.
Are all GLP-1 medications FDA-approved?
No. Semaglutide and tirzepatide are FDA-approved. Retatrutide, a triple GIP, GLP-1 and glucagon receptor agonist, is investigational and has not completed the FDA approval process, so it cannot legally be bought or prescribed.
What is the difference between a GLP-1 agonist and a dual agonist?
A GLP-1 agonist, like semaglutide, activates one hormone receptor. A dual agonist, like tirzepatide, activates that same GLP-1 receptor plus a second one, GIP. The extra receptor is the leading explanation for tirzepatide’s stronger measured result in SURMOUNT-5.
Is retatrutide a GLP-1 medication?
Yes, in that it activates the GLP-1 receptor as one of its three targets, alongside GIP and glucagon. It is more precisely described as a triple GIP, GLP-1 and glucagon receptor agonist, and it remains investigational: it cannot legally be prescribed.
Why is compounded GLP-1 not the same as the FDA-approved version?
A compounded preparation contains the same active ingredient as the FDA-approved brand-name product, but the compounded product itself has not gone through FDA approval, even when the pharmacy that compounds it is properly FDA-registered. Registration of the pharmacy and approval of the specific product are two different things.
Do GLP-1 medications have the same side effects?
The class shares a hallmark pattern: gastrointestinal side effects, mostly mild to moderate and occurring primarily during dose escalation, reported for both semaglutide and tirzepatide in SURMOUNT-5. No trial has directly compared incidence rates for all three drugs discussed on this page in a single study.