The GLP-1 class has moved further in five years than weight-loss pharmacotherapy moved in the previous fifty. Liraglutide hit the market in 2010 with single-digit weight loss. Wegovy doubled that in 2021. Zepbound roughly tripled it in 2023. Retatrutide, in Phase III as of May 2026, has reported a fourth scale-up. The sequence is not random. Each step adds either a receptor or a kinetic improvement that the previous generation lacked.
This article compares every GLP-1 drug currently relevant to clinical practice on the variables that matter: how much weight they produce, how often they are dosed, how long they last in circulation, what receptors they bind, and what they cost. The data is drawn from published Phase III trials and current US list prices as of May 2026. For the underlying mechanism see How GLP-1 Agonists Work. For the head-to-head between the two top approved compounds see Semaglutide vs Tirzepatide.
One caveat applies to every figure that follows. Trial weight loss is not real-world weight loss. Trial participants receive structured lifestyle support and free medication. Real-world patients usually do not. The class-wide rule is that real-world weight loss runs at roughly 60 to 75% of trial figures. A 22.5% trial result corresponds to roughly 14 to 17% in clinical use. Read every number in this chart with that adjustment in mind.
The four compounds that matter in 2026
Five GLP-1 receptor agonists have been approved by the FDA, but only four are clinically relevant for weight management in 2026. Exenatide (Byetta, approved 2005) is still available for type 2 diabetes but has been functionally replaced by longer-acting compounds. Dulaglutide (Trulicity, approved 2014) remains a diabetes drug only and was never developed for weight-loss indications. The four that matter for weight management are liraglutide, semaglutide, tirzepatide, and the investigational retatrutide.
- Liraglutide (Saxenda)First GLP-1 acylated for albumin binding. Approved by Novo Nordisk in 2014 for weight loss at 3.0mg daily. Daily subcutaneous injection. Half-life ~13 hours. SCALE trial reported 8.0% mean weight loss over 56 weeks. Now largely displaced by semaglutide but remains the only daily-dose option.
- Semaglutide (Wegovy)First once-weekly GLP-1 for weight loss. Approved June 2021 at 2.4mg weekly. STEP 1 reported 14.9% mean weight loss over 68 weeks. Half-life ~7 days. Backed by SELECT cardiovascular outcome data showing 20% MACE reduction in 17,604 patients with established CVD.
- Tirzepatide (Zepbound)First dual GLP-1 + GIP agonist approved for weight loss. Approved November 2023 at doses up to 15mg weekly. SURMOUNT-1 reported 22.5% mean weight loss over 72 weeks. Half-life ~5 days. SURMOUNT-5 showed superior weight loss versus semaglutide in direct head-to-head comparison.
- Retatrutide (LY3437943, investigational)First triple GLP-1 + GIP + glucagon agonist in Phase III. TRIUMPH-4 reported 28.7% mean weight loss at 12mg over 68 weeks. Half-life ~6 days. NDA submission expected late 2026, approval likely 2027 or 2028. Introduces a new dysesthesia signal not seen in earlier compounds.
A handful of investigational compounds sit one step behind retatrutide. Orforglipron (Eli Lilly) is an oral small-molecule GLP-1 agonist in Phase III with Phase II weight loss in the 9 to 15% range. Mazdutide (Innovent) is a dual GLP-1 + glucagon agonist also in Phase III, primarily targeting the Chinese market. Survodutide (Boehringer Ingelheim / Zealand) is another dual GLP-1 + glucagon agonist in Phase III. None have reported full Phase III readouts at the time of publication.
The full comparison chart
The table below summarises the four clinically-relevant GLP-1 drugs on every variable that affects prescribing decisions in 2026. All figures are taken from published Phase III trials. Prices are US list prices without insurance, expressed per 28-day supply.
| Compound | Brand | Receptors | Top dose | Trial loss | Half-life | Dosing | List price |
|---|---|---|---|---|---|---|---|
| Liraglutide | Saxenda | GLP-1 | 3.0mg | 8.0% | ~13 hr | Daily SC | ~$1,350 |
| Semaglutide | Wegovy | GLP-1 | 2.4mg | 14.9% | ~7 days | Weekly SC | ~$1,350 |
| Tirzepatide | Zepbound | GLP-1 + GIP | 15mg | 22.5% | ~5 days | Weekly SC | ~$1,060 |
| Retatrutide | Pending | GLP-1 + GIP + Glucagon | 12mg | 28.7% | ~6 days | Weekly SC | TBD |
Every approved compound is administered subcutaneously. Oral semaglutide (Rybelsus) exists but is approved for type 2 diabetes only, not weight loss. Investigational orforglipron is the first realistic oral candidate for weight management, with Phase III readouts expected in 2026.
How efficacy stacks up
The single clearest pattern in the data is that adding receptors adds weight loss. Liraglutide and semaglutide both bind only GLP-1, but semaglutide produces nearly double the weight loss because of its longer half-life and higher labelled dose. Tirzepatide adds GIP and gains roughly 7 percentage points over semaglutide. Retatrutide adds glucagon and gains roughly 6 percentage points over tirzepatide. The pattern is consistent.
The only direct head-to-head comparison published to date is SURMOUNT-5 (Aronne et al., NEJM, 2025), which compared tirzepatide and semaglutide at their highest approved weight-loss doses over 72 weeks. Tirzepatide produced 20.2% weight loss versus 13.7% for semaglutide. The 6.5-point gap is consistent with what would be predicted by comparing SURMOUNT-1 and STEP 1 separately. The trial confirmed that the Phase III hierarchy holds up under controlled head-to-head conditions.
Retatrutide also reported a clear dose-response in TRIUMPH-4. The 9mg arm produced 26.4% weight loss versus 28.7% at 12mg, a modest but consistent increment. Discontinuation rates rose from 12.2% at 9mg to 18.2% at 12mg, primarily driven by the new dysesthesia signal at the higher dose. This is the first compound in the class where dose escalation past a certain point appears to trade safety for efficacy in a meaningful way. For the underlying mechanism see Triple vs Dual Agonism.
Dosing, titration, and administration
Every GLP-1 agonist requires titration. Starting at the labelled top dose causes severe nausea and frequent discontinuation. The standard approach is to start at the lowest dose and step up every four weeks until the maintenance dose is reached. This typically takes 16 to 20 weeks before a patient is on full therapeutic dosing.
Liraglutide is the only daily injection, starting at 0.6mg and titrating in 0.6mg increments to 3.0mg over five weeks. Semaglutide starts at 0.25mg weekly and steps up to 2.4mg over 16 weeks. Tirzepatide starts at 2.5mg weekly and steps up to 15mg over 20 weeks. Retatrutide's titration in TRIUMPH-4 started at 2mg weekly and reached 12mg over 16 to 20 weeks depending on tolerability.
All four are administered using prefilled subcutaneous auto-injectors into the abdomen, thigh, or upper arm. Injection site rotation is recommended to reduce local irritation. None require refrigeration once in use, though they should be stored cold before first use. Storage requirements are similar across brands.
Cost, insurance, and access
US list prices in 2026 sit between roughly $1,000 and $1,350 per 28-day supply. Wegovy lists at approximately $1,350 per month. Zepbound lists at approximately $1,060 per month. Saxenda is comparable to Wegovy in pricing. The diabetes indications (Ozempic and Mounjaro) sit slightly lower at roughly $1,000 to $1,070 per month, though the difference is partly explained by older negotiated rates. Retatrutide pricing has not been disclosed.
Insurance coverage for weight-loss indications remains inconsistent. Most US commercial plans cover at least one GLP-1 for type 2 diabetes. Coverage for obesity treatment is less universal, with prior authorisation requirements, step-therapy protocols, and BMI cutoffs varying widely across plans. Medicare expanded coverage of GLP-1s for cardiovascular indications in 2025 following the SELECT trial readout, but standalone obesity coverage remains limited.
Compounded GLP-1s are no longer a routine option. The FDA designated semaglutide and tirzepatide as resolved shortages in late 2024 and early 2025, ending the legal basis for routine 503A pharmacy compounding under FDCA section 503A. Personalised 503A compounding for individual clinical need still exists in a limited form but is not a meaningful price-substitute pathway. Patients seeking lower-cost access are now generally limited to manufacturer savings programs, Canadian or Mexican pharmacy imports (legally complex), or waiting for orforglipron approval if oral pricing follows historical patterns.
Frequently Asked Questions
Which GLP-1 drug produces the most weight loss in 2026?
Retatrutide produces the most weight loss in head-to-head trial comparisons, but it is not yet FDA-approved. TRIUMPH-4 reported 28.7% mean weight loss at 12mg over 68 weeks, with NDA submission expected in late 2026 and approval likely in 2027 or 2028. Of currently-approved drugs, tirzepatide (Zepbound) leads at 22.5% from SURMOUNT-1 over 72 weeks. Semaglutide (Wegovy) follows at 14.9% from STEP 1 over 68 weeks. Liraglutide (Saxenda) trails at 8.0% from SCALE over 56 weeks.
How does tirzepatide compare to semaglutide head-to-head?
SURMOUNT-5 (Aronne et al., NEJM, 2025) directly compared the two compounds at their highest approved weight-loss doses over 72 weeks. Tirzepatide produced 20.2% mean weight loss versus 13.7% for semaglutide. The difference is approximately 6.5 percentage points, consistent with the gap predicted by SURMOUNT-1 and STEP 1 individually. Tirzepatide's added GIP receptor activity is the likely explanation, though direct mechanistic attribution remains debated.
What is the difference in receptor coverage across the class?
Liraglutide and semaglutide bind only the GLP-1 receptor. Tirzepatide binds GLP-1 and GIP, making it a dual agonist. Retatrutide binds GLP-1, GIP, and glucagon, making it the first triple agonist in late-stage trials. Each receptor added in the sequence has produced approximately 5 to 7 percentage points of additional weight loss in Phase III trials, suggesting the mechanisms combine additively rather than compete.
How long do these drugs stay in the body?
Half-lives range from 13 hours for liraglutide (daily dosing) to roughly seven days for semaglutide (weekly dosing). Tirzepatide and retatrutide both sit at around five to six days. Native GLP-1 has a half-life of approximately two minutes, which is why every drug version is engineered with structural modifications (typically a fatty acid chain that binds serum albumin) to resist enzymatic breakdown by DPP-4.
What does each GLP-1 drug cost in the US?
Without insurance, US list prices in 2026 are roughly $1,350 per month for Wegovy (semaglutide for weight loss), $1,060 per month for Zepbound (tirzepatide for weight loss), $1,000 per month for Ozempic (semaglutide for diabetes), and $1,070 per month for Mounjaro (tirzepatide for diabetes). Compounded versions are no longer legally available through 503A pharmacies. The FDA designated semaglutide and tirzepatide as resolved shortages in late 2024 and early 2025, ending the legal basis for routine compounding.
Is real-world weight loss the same as trial weight loss?
No. Real-world weight loss across the GLP-1 class typically runs at roughly 60 to 75% of trial figures. Trial participants receive structured lifestyle support, monthly check-ins, and free medication. Real-world patients deal with insurance gaps, missed doses, slower titration, and inconsistent adherence. A trial figure of 22.5% should be set against a real-world expectation closer to 14 to 17%.
Which GLP-1 drug has the best safety profile?
Semaglutide and tirzepatide both have well-characterised long-term safety records based on years of post-approval data and large outcome trials such as SELECT (semaglutide, 17,604 patients). Retatrutide introduced a new safety signal in TRIUMPH-4: dysesthesia in 20.9% of participants at 12mg versus 0.7% on placebo, not seen in GLP-1-only or GLP-1+GIP compounds. Liraglutide has the longest track record overall (approved 2010) but produces the smallest weight loss. For full discussion of class-wide safety patterns see the GLP-1 Safety Profile.
Are oral GLP-1 alternatives competitive with injectable versions?
Oral semaglutide (Rybelsus) is approved for type 2 diabetes but not for weight loss. The oral formulation requires fasting administration and absorption is limited, restricting practical dosing. Orforglipron, an investigational small-molecule GLP-1 agonist from Eli Lilly, is in Phase III trials and would not require the absorption-enhancer technology of oral semaglutide. Phase II data showed weight loss in the 9 to 15% range. Approval is expected in 2026 or 2027 if Phase III readouts continue the trend.
This article is for informational and educational purposes only and does not constitute medical advice. GLP-1 agonists are prescription medications with a range of indications, contraindications, and side effects. Pricing and access information is based on publicly available US list prices as of May 2026 and may not reflect insurance coverage, manufacturer rebates, or out-of-pocket cost. Retatrutide is investigational and has not been approved by the FDA, EMA, MHRA, or any other regulatory agency as of May 2026. Consult a licensed healthcare provider before starting, stopping, or changing any medication.
Last updated: May 2026.