Side-by-side guide
Semaglutide vs Tirzepatide: the full guide
An honest, clinically-framed comparison of Semaglutide and Tirzepatide — what they do, how they differ, what the evidence shows, and who each tends to suit.
Quick comparison at a glance
The short version — here is how Semaglutide and Tirzepatide stack up on the questions most patients ask before picking one.
Semaglutide
- Drug class: GLP-1 receptor agonist
- Brand names: Wegovy, Ozempic, Rybelsus
- Mechanism: Mimics the gut hormone GLP-1 to reduce appetite, slow gastric emptying, and improve insulin sensitivity.
- Dosing: Once-weekly subcutaneous injection. Titrated from 0.25 mg to 2.4 mg over about 16 weeks for weight management.
- Half-life: Approximately 7 days, which is why it's dosed weekly.
- FDA indication: Chronic weight management in adults with obesity (BMI ≥30) or overweight (BMI ≥27) with at least one weight-related condition (brand: Wegovy). Also FDA-approved for type 2 diabetes under the brand Ozempic.
- FDA status: FDA-approved as a finished drug product under the brand names Wegovy and Ozempic. Compounded semaglutide is NOT FDA-approved.
- Manufacturer: Novo Nordisk
- Common side effects: Nausea, vomiting, diarrhea, constipation, decreased appetite. Usually mild and transient during dose escalation.
- Typical price range: Brand Wegovy runs roughly $1,300+/month cash price without insurance. Compounded semaglutide through Puri starts at $179/month when clinically appropriate.
Tirzepatide
- Drug class: Dual GLP-1 and GIP receptor agonist
- Brand names: Zepbound, Mounjaro
- Mechanism: Acts on both GLP-1 and GIP receptors simultaneously. GIP activation adds an additional layer of appetite and glucose regulation beyond pure GLP-1 agonism.
- Dosing: Once-weekly subcutaneous injection. Titrated from 2.5 mg to a maximum of 15 mg over about 20-24 weeks.
- Half-life: Approximately 5 days, still appropriate for weekly dosing.
- FDA indication: Chronic weight management in adults with obesity (BMI ≥30) or overweight (BMI ≥27) with at least one weight-related condition (brand: Zepbound). Also FDA-approved for type 2 diabetes under the brand Mounjaro.
- FDA status: FDA-approved as a finished drug product under the brand names Zepbound and Mounjaro. Compounded tirzepatide is NOT FDA-approved.
- Manufacturer: Eli Lilly
- Common side effects: Similar profile to semaglutide — nausea, vomiting, diarrhea, constipation, decreased appetite. Some patients report slightly higher GI side effects at the highest doses.
- Typical price range: Brand Zepbound runs roughly $1,100-1,400/month cash price without insurance. Compounded tirzepatide through Puri starts at $249/month when clinically appropriate.
How they work: GLP-1 vs GLP-1 + GIP
Semaglutide and tirzepatide both belong to the broader class of incretin-based therapies, but they are not the same drug and they are not interchangeable. Understanding the mechanism difference matters because it helps explain why one patient might respond better to one than the other.
GLP-1 (glucagon-like peptide-1) is a hormone your gut releases after you eat. It signals the pancreas to release insulin, slows how fast your stomach empties, and — most importantly for weight management — reduces appetite by acting on receptors in the brain. Semaglutide is a synthetic analog of GLP-1 that resists rapid breakdown, allowing once-weekly dosing.
GIP (glucose-dependent insulinotropic polypeptide) is another gut hormone that works alongside GLP-1. GIP amplifies insulin release after meals and appears to have additional effects on fat metabolism and energy expenditure. Tirzepatide is a dual agonist — it activates both GLP-1 and GIP receptors simultaneously, which is why it produced greater average weight loss in clinical trials than GLP-1-only drugs.
Whether GIP agonism translates to a clinically meaningful advantage for any individual patient depends on the individual. Some patients see dramatic results on semaglutide alone. Others need the dual mechanism to make progress. A physician evaluates your metabolic picture, comorbidities, and treatment history to decide which is appropriate.
What the clinical trials actually showed
Both medications went through rigorous Phase 3 clinical trials before FDA approval. Looking at the actual trial data matters because media coverage often mixes up doses, durations, and populations.
Semaglutide — STEP 1 trial
The STEP 1 trial (New England Journal of Medicine, 2021) enrolled 1,961 adults with a BMI of 30 or more (or 27 or more with at least one weight-related condition, excluding type 2 diabetes). Participants received weekly semaglutide 2.4 mg or placebo for 68 weeks, both combined with lifestyle intervention. The average weight loss was about 14.9% of body weight in the semaglutide arm compared to about 2.4% in placebo.
Tirzepatide — SURMOUNT-1 trial
The SURMOUNT-1 trial (New England Journal of Medicine, 2022) enrolled 2,539 adults with similar eligibility criteria. Participants received weekly tirzepatide at 5 mg, 10 mg, or 15 mg, or placebo, for 72 weeks, again combined with lifestyle intervention. Average weight loss was approximately 15.0%, 19.5%, and 20.9% at 5 mg, 10 mg, and 15 mg respectively, versus about 3.1% for placebo.
A few important caveats on comparing the trials directly. STEP 1 and SURMOUNT-1 used different populations, different primary endpoints, and different trial durations. The 5 mg tirzepatide result (15%) was broadly similar to the 2.4 mg semaglutide result (14.9%) — the dramatic differences show up at higher tirzepatide doses. Individual response is highly variable and the average is not a prediction for any single patient.
Average weight loss numbers from clinical trials are averages. Some patients in both trials lost 20-25% of body weight. Others lost only 5% or less. Your individual result depends on genetics, metabolism, baseline weight, lifestyle, adherence, and many factors that aren't knowable in advance.
Side effects: the honest picture
Both medications have similar side effect profiles because both slow gastric emptying and modulate appetite through central nervous system effects. The most common issues are gastrointestinal.
- Nausea. The most common side effect of both. Typically mild, most prominent during dose escalation, and usually improves over the first 4-8 weeks.
- Vomiting, diarrhea, constipation. Less common than nausea but real for a subset of patients. Titrating up slowly and staying hydrated helps.
- Decreased appetite. This is the intended effect, but it can be disorienting at first. Making sure you still eat protein and nutrient-dense food matters — losing muscle alongside fat is a known concern with any aggressive calorie-restriction treatment.
- Fatigue and headache. Reported by a minority of patients, especially during early dose escalation.
- Rare but serious: pancreatitis, gallbladder issues, and kidney effects. These are uncommon but require immediate medical attention. Both drugs have FDA boxed warnings regarding thyroid C-cell tumors based on animal studies — personal or family history of medullary thyroid carcinoma (MTC) or MEN2 is an absolute contraindication.
Some patients report slightly higher GI side effects at the highest doses of tirzepatide, but the overall safety profile is similar to semaglutide and both are well-tolerated by the majority of patients when dosed appropriately.
Cost and access: the practical reality
The cost picture for GLP-1 medications is complicated and changes based on insurance coverage, manufacturer programs, shortages, and the availability of compounded options.
Brand-name Wegovy and Zepbound
Without insurance, brand-name Wegovy is roughly $1,300+/month at retail pharmacies, and brand-name Zepbound is roughly $1,100-1,400/month. Manufacturer savings cards can reduce cost for eligible commercially-insured patients. Insurance coverage varies enormously — some employer plans cover these for obesity at the FDA-approved indication with prior authorization; others do not.
Compounded semaglutide and tirzepatide
When the FDA declares a shortage of a brand-name product, licensed compounding pharmacies may prepare custom formulations under a valid prescription. Puri's compounded semaglutide program starts at $179/month and compounded tirzepatide at $249/month when clinically appropriate. These are NOT FDA-approved products and have not been evaluated for equivalence to the brand-name versions.
Compounded medications exist because of documented shortages and because some patients need custom formulations for medical reasons. They are not the same thing as the brand-name product. A licensed physician should weigh the tradeoffs with you before you start either path.
Who tends to do better on each
There is no universally better option — only a better fit for your specific clinical picture, history, budget, and preferences. A licensed physician reviews all of those before prescribing. Here is the honest framing on who typically does better on each.
Semaglutide
Semaglutide is a well-established option with the longest track record for weight management. It tends to be a good fit for patients who want the most clinical evidence, who respond well to once-weekly GLP-1-only dosing, or for whom tirzepatide is unavailable or too expensive. Many patients achieve meaningful weight loss on semaglutide without needing to escalate to a dual agonist.
Tirzepatide
Tirzepatide tends to be a good fit for patients who didn't respond adequately to semaglutide, who are targeting higher average weight loss, or whose provider judges that the dual GLP-1/GIP mechanism is clinically warranted. Average weight loss in SURMOUNT-1 at the highest doses was greater than in STEP 1 for semaglutide, though individual results vary substantially.
A prescription is not guaranteed. Your Puri-affiliated provider may decline to prescribe either medication if the clinical picture does not support it, if you have a contraindication, or if a different treatment is more appropriate for your situation. You will not be charged for medication you do not receive.
