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Semaglutide vs Tirzepatide: Weight Loss, Side Effects, and Cost Compared

Tirzepatide produced 20.2% average weight loss against semaglutide at 13.7% in the first head-to-head trial. Compare mechanisms, side effects, and what each costs in 2026.

Key Takeaways

Tirzepatide produces more weight loss than semaglutide: 20.2% versus 13.7% of body weight in the SURMOUNT-5 head-to-head trial at 72 weeks. Semaglutide remains a proven medication with 14.9% average loss in its own trials and costs substantially less, with telehealth programs from $99 per month versus $349-$699 for tirzepatide through LillyDirect. Choose tirzepatide for maximum effect if budget allows; choose semaglutide for proven results at half the price or less.

Semaglutide vs Tirzepatide at a Glance

FeatureSemaglutideTirzepatide
MechanismGLP-1 receptor agonistDual GIP + GLP-1 receptor agonist
Brand namesWegovy (weight), Ozempic (T2D)Zepbound (weight, OSA), Mounjaro (T2D)
Average weight loss (own trials)14.9% at 68 weeks (STEP 1)20.9% at 72 weeks (SURMOUNT-1)
Head-to-head (SURMOUNT-5)13.7% at 72 weeks20.2% at 72 weeks
DosingWeekly injection, titrated to 2.4mgWeekly injection, titrated to 15mg
Common side effectsNausea, vomiting, constipation, diarrheaSame class effects, similar or slightly lower rates
Branded self-pay priceWegovy $499/month (NovoCare)Zepbound $349-$699/month (LillyDirect vials)
Telehealth program priceFrom $99/month (compounded programs)Branded channels only since 2025
Cardiovascular outcome dataYes (SELECT trial, 20% MACE reduction)Not yet published for weight-loss population

About This Comparison

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This weight loss provider comparison is independently researched by our editorial team. We compare telehealth services based on publicly available information including pricing, available treatments, service areas, and verified customer reviews.

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Semaglutide vs Tirzepatide: Weight Loss, Side Effects, and Cost Compared

Eric GoldWritten by Eric GoldEditor-in-Chief
10 min read

Semaglutide (sold as Wegovy and Ozempic) and tirzepatide (sold as Zepbound and Mounjaro) are the two dominant injectable weight loss medications in the US, and 2025 delivered the comparison the field waited for: SURMOUNT-5, the first large head-to-head randomized trial, found tirzepatide produced 20.2% average body weight loss versus 13.7% for semaglutide at 72 weeks. That is a real difference, and it is not the whole story. Semaglutide has its own strong evidence base, with STEP 1 recording 14.9% average loss, plus a cardiovascular outcomes trial showing reduced heart attack and stroke risk, and it costs dramatically less: telehealth semaglutide programs start at $99 per month while branded tirzepatide runs $349-$699 through LillyDirect vials. This comparison walks through the mechanism difference, the trial data, tolerability, and the cost math so you can decide whether the extra weight loss justifies the extra spend for your situation.

One Hormone vs Two: Why Tirzepatide Loses More Weight

Semaglutide mimics one gut hormone: GLP-1 (glucagon-like peptide-1), which slows stomach emptying, signals fullness to the brain, and improves insulin response. Tirzepatide mimics two: GLP-1 plus GIP (glucose-dependent insulinotropic polypeptide). The dual action appears to amplify appetite suppression and improve how the body handles fat and glucose beyond what GLP-1 alone achieves, and the trial numbers reflect it consistently across every comparison run so far.
The practical translation: on average, a 240-pound person loses roughly 33 pounds on semaglutide and roughly 48 pounds on tirzepatide over about a year and a half. Averages hide spread in both directions; strong responders on semaglutide beat weak responders on tirzepatide, and roughly one in six patients on either drug loses less than 5% of body weight. No test yet predicts your response, which argues for judging your own 3-month results over any population average.

What the Trials Actually Show

The evidence base for both drugs is unusually strong for medications this new. STEP 1 (semaglutide 2.4mg, published in the New England Journal of Medicine 2021) recorded 14.9% average body weight loss over 68 weeks versus 2.4% on placebo, with 86% of participants losing at least 5%. SURMOUNT-1 (tirzepatide, NEJM 2022) recorded 20.9% at the 15mg dose over 72 weeks, with 91% losing at least 5%. Cross-trial comparisons are unreliable, which is why SURMOUNT-5 mattered: same trial, same conditions, tirzepatide 20.2% versus semaglutide 13.7%.
Semaglutide holds one card tirzepatide does not yet: published cardiovascular outcomes in a weight-loss population. The SELECT trial found semaglutide reduced major adverse cardiac events by 20% in people with obesity and existing cardiovascular disease. For patients whose primary concern is heart risk rather than maximum weight loss, that evidence tilts the decision toward semaglutide until tirzepatide publishes equivalent data.

Side Effects and Tolerability

Both drugs share the same gastrointestinal side effect profile because both slow stomach emptying: nausea leads, followed by vomiting, constipation, and diarrhea, concentrated during dose escalation and improving as your body adapts. In SURMOUNT-5, side effect rates were broadly similar between arms, with gastrointestinal events in the same range despite tirzepatide producing substantially more weight loss, and some analyses suggest tirzepatide is slightly better tolerated at equivalent efficacy, possibly related to the GIP component.
The management playbook is identical for both: slow titration, smaller meals, less fat and alcohol during escalation, hydration, and telling your provider rather than quietly quitting, because dose adjustments resolve most tolerability problems. Serious risks are rare and shared across the class: pancreatitis, gallbladder disease (which rapid weight loss itself promotes), and a thyroid C-cell tumor warning from rodent data that excludes people with personal or family history of medullary thyroid carcinoma. Neither drug is used in pregnancy. Muscle loss accompanies any rapid weight loss, which is why protein intake and resistance training belong in every GLP-1 protocol regardless of molecule.

Cost and Access: Where Semaglutide Wins

The price gap is the strongest argument for semaglutide. Compounded semaglutide programs through telehealth run $99-$227 per month (Strut Health from $99, MEDVi and TrimRx from $179), and branded Wegovy costs $499 per month through the NovoCare self-pay channel. Tirzepatide has no comparable budget lane: since compounded tirzepatide lost its legal basis in early 2025, the cheapest branded route is LillyDirect vials at $349 per month for the starting dose, rising to $499-$699 at maintenance doses.
A year of treatment therefore runs roughly $1,200-$2,700 on compounded semaglutide, $6,000 on branded Wegovy, and $4,200-$6,700 on tirzepatide vials. Insurance changes everything where it applies: 38% of large employer plans covered GLP-1s for weight loss in 2025 per Kaiser Family Foundation data, and covered patients with manufacturer savings cards can pay as little as $25 per month for either brand. Check coverage first; the entire self-pay comparison is moot if your plan covers one of the two.

Which Should You Choose?

The decision reduces to three questions. First, coverage: if insurance covers one drug and not the other, take the covered one; a 6-7 point average efficacy difference does not justify $5,000+ per year out of pocket when a covered alternative exists. Second, budget: if you are self-pay and $349-$699 per month is comfortable, tirzepatide is the efficacy choice; if not, semaglutide at $99-$227 delivers the majority of the benefit at a fraction of the price, and 13.7-14.9% average body weight loss remains a life-changing result by any pre-2021 standard.
Third, your specific health picture: existing cardiovascular disease favors semaglutide for its published SELECT outcomes data; a diagnosis of obstructive sleep apnea favors tirzepatide, whose Zepbound label includes OSA and opens insurance pathways semaglutide lacks; type 2 diabetes reroutes the whole question through Ozempic and Mounjaro coverage, which is usually generous for both. And if you start one and stall or tolerate it poorly, switching within the class is routine clinical practice; a meaningful share of semaglutide non-responders do well on tirzepatide.

Frequently Asked Questions

Is tirzepatide really better than semaglutide for weight loss?

On population averages, yes, and the evidence is unusually clean. SURMOUNT-5, the head-to-head randomized trial published in the New England Journal of Medicine, put the same kinds of patients on each drug under identical conditions for 72 weeks: tirzepatide averaged 20.2% body weight loss against 13.7% for semaglutide, a difference of roughly 15 pounds for a 240-pound starting weight, and more tirzepatide patients hit the 15% and 20% loss thresholds. The caveats that keep this honest: averages hide wide individual spread, strong semaglutide responders outperform weak tirzepatide responders, and about one in six patients on either drug responds minimally. Semaglutide also carries published cardiovascular outcomes data (a 20% reduction in major cardiac events in the SELECT trial) that tirzepatide has not yet matched in a weight-loss population. Better on average does not mean better for every person or every priority.

What is the difference between Ozempic, Wegovy, Mounjaro, and Zepbound?

Two molecules, four labels. Ozempic and Wegovy are both semaglutide: Ozempic carries the type 2 diabetes label with doses up to 2mg, while Wegovy carries the weight management label with doses up to 2.4mg. Mounjaro and Zepbound are both tirzepatide: Mounjaro for type 2 diabetes, Zepbound for weight management and, since December 2024, obstructive sleep apnea. The medications inside matching pairs are identical; the labels exist because the FDA approves drugs per indication, and the labels drive insurance. Diabetes-labeled products enjoy broad formulary coverage with a T2D diagnosis, while weight-labeled products face exclusions and prior authorization. That is why your diagnosis, not the marketing name, determines which product you should pursue: T2D routes you through Ozempic or Mounjaro coverage, weight management routes you through Wegovy or Zepbound channels, and sleep apnea opens a Zepbound-specific coverage lane.

Which has worse side effects, semaglutide or tirzepatide?

They are more alike than different. Both slow stomach emptying, so both produce the same gastrointestinal profile: nausea most commonly, then vomiting, constipation, and diarrhea, concentrated during dose escalation and easing as your body adapts. In the SURMOUNT-5 head-to-head, adverse event rates were broadly similar between arms, which is mildly favorable for tirzepatide given it produced substantially more weight loss; some endocrinologists read the GIP component as slightly improving tolerability at equivalent effect. Individual variation swamps the average difference, though: some patients tolerate one and not the other, and switching within the class over tolerability is routine. The serious-but-rare risks are shared: pancreatitis, gallbladder disease, and the thyroid C-cell warning that excludes anyone with personal or family medullary thyroid carcinoma history. Management is identical for both: slow titration, smaller and lower-fat meals, hydration, and dose adjustment through your provider rather than silent discontinuation.

How much more does tirzepatide cost than semaglutide?

Self-pay, the gap is large. Semaglutide has a budget lane tirzepatide lacks: compounded telehealth programs from $99-$227 per month (Strut Health at $99, MEDVi and TrimRx at $179), with branded Wegovy at $499 through NovoCare. Tirzepatide runs $349 per month for the 2.5mg starting dose through LillyDirect vials and $499-$699 at the maintenance doses most patients reach, with no legal compounded alternative since early 2025. Annualized: $1,200-$2,700 for compounded semaglutide, about $6,000 for branded Wegovy, $4,200-$6,700 for tirzepatide vials. Insurance collapses the difference where it applies: covered patients with manufacturer savings cards can pay $25 per month for either brand, which is why checking your formulary is the mandatory first step. The efficiency framing: at average trial results, semaglutide delivers roughly two-thirds of tirzepatide weight loss for as little as one-quarter of the self-pay cost.

Can I switch from semaglutide to tirzepatide?

Yes, and it is one of the most common switches in obesity medicine. The typical reasons: a plateau after 6+ months on maximum tolerated semaglutide, minimal response from the start, or persistent tolerability problems. Providers generally transition directly, starting tirzepatide at a low-to-mid dose rather than the very bottom of the titration ladder, adjusted for how much semaglutide you were taking; there is no required washout period, though your provider will time the first tirzepatide dose against your last semaglutide injection. Expectations should stay realistic: switching helps a meaningful share of semaglutide non-responders and plateaued patients, but it is not guaranteed, and some of the plateau effect reflects physiology common to both drugs. The reverse switch, tirzepatide to semaglutide, also happens, usually driven by cost or by insurance changes rather than efficacy. Either direction, make the change through your prescriber; the dose mapping between the two titration schedules is not intuitive.

Do I regain the weight if I stop either medication?

The evidence says mostly yes, for both drugs equally. The STEP 1 trial extension followed participants after semaglutide discontinuation and recorded regain of roughly two-thirds of lost weight within a year, and tirzepatide withdrawal data from the SURMOUNT-4 trial shows the same pattern: continued treatment maintained or extended loss while switching to placebo produced steady regain. The mechanism is straightforward: these drugs suppress appetite while present, and the underlying appetite biology returns when they clear. This has two practical implications for your comparison. First, budget for maintenance, not a one-year course; the honest cost comparison between semaglutide and tirzepatide is a multi-year number. Second, use the treatment window to build the durable infrastructure, protein-forward eating habits, resistance training, and sleep, that moderates regain when and if you eventually taper. Some patients maintain on reduced doses or longer injection intervals; that is an active conversation to have with your provider rather than a self-managed experiment.

Sources & References

Our comparisons are informed by official sources and regulatory guidelines. We encourage readers to verify information with authoritative sources.

Editorial Note: Researched and edited by our editorial team. AI tools assist with initial research and drafting; all content is fact-checked and edited by humans before publication. Learn more about our editorial standards

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Medical Disclaimer: This comparison is for informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before starting or changing any medication. Individual results and experiences may vary. Read our full medical disclaimer.