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Should I start with tirzepatide or semaglutide as my first peptide?

Updated 2026-05-03

Tirzepatide tends to drive larger weight loss because it works on two hormone pathways instead of one. Semaglutide has a longer real-world track record and the strongest cardiovascular safety data. For pure weight loss with no heart-disease risk factors, most clinicians lean tirzepatide. For patients with cardiovascular history or who want the most studied option, semaglutide is the safer bet. Both are once-weekly injections with similar early side effects.

IfIf your main goal is the biggest possible weight loss
Thenthen tirzepatide averaged 20.9% loss at 72 weeks in SURMOUNT-1 vs semaglutide's 14.9% at 68 weeks in STEP 1
IfIf you have known cardiovascular disease or high heart-risk factors
Thenthen semaglutide has the SELECT trial cardiovascular outcomes data behind it
IfIf you have severe nausea on one of them
Thenthen talk to your provider about whether switching makes sense; some people tolerate tirzepatide better because GIP may blunt nausea
IfIf cost is a hard constraint
Thenthen compounded semaglutide is typically cheaper than compounded tirzepatide on a per-month basis
Key facts
  • Semaglutide is a single GLP-1 receptor agonist; tirzepatide is a dual GIP and GLP-1 agonist
  • SURMOUNT-1 (NCT04184622) showed 20.9% mean weight loss with tirzepatide 15 mg at 72 weeks
  • STEP 1 (NCT03548935) showed 14.9% mean weight loss with semaglutide 2.4 mg at 68 weeks
  • Both are typically started low and increased gradually; your provider sets the exact schedule
  • Tirzepatide users in head-to-head data are more likely to hit 20%+ weight loss
  • Semaglutide is sold as Wegovy in the US for obesity; tirzepatide is sold as Zepbound
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