Semaglutide vs Tirzepatide
Semaglutide and tirzepatide are the two most prescribed weight management peptides in the world. Both require weekly injections and gradual titration, but they work through different mechanisms and produce different outcomes.
| Metric | Semaglutide | Tirzepatide |
|---|---|---|
| Category | Weight Management | Weight Management |
| Default Unit | mg | mg |
| Vial Sizes | 2, 3, 5, 10 | 5, 10, 15, 30 |
| Dose Range | 0.25–2.4 mg | 2.5–15 mg |
| Frequency | Weekly | Weekly |
| Stability | 28 days | 28 days |
| Powder Storage | Freezer −20°C | Freezer −20°C |
| Reconstituted | Fridge 2–8°C | Fridge 2–8°C |
Mechanism of Action
Semaglutide targets a single receptor (GLP-1), while tirzepatide is a dual agonist targeting both GLP-1 and GIP receptors. The dual mechanism is theorized to provide enhanced metabolic benefits including greater insulin sensitivity and potentially superior appetite suppression. Think of semaglutide as a single-lane highway and tirzepatide as a two-lane — both get you there, but one has more throughput.
Weight Loss Results
In the STEP trials, semaglutide 2.4 mg produced average weight loss of 15–17% over 68 weeks. In the SURMOUNT trials, tirzepatide 15 mg produced average weight loss of 20–22.5% over 72 weeks. Head-to-head data from SURPASS-2 confirmed tirzepatide's superiority at matched dose escalation timelines. However, individual results vary significantly — some people respond better to one than the other.
Titration & Dosing
Both require 16–20+ weeks of gradual dose escalation. Semaglutide: 0.25 → 0.5 → 1.0 → 1.7 → 2.4 mg. Tirzepatide: 2.5 → 5 → 7.5 → 10 → 12.5 → 15 mg. Tirzepatide has more dose steps, giving more flexibility to find an effective dose with tolerable side effects. Many users find their sweet spot at 7.5–10 mg and don't need to go to 15.
Side Effects
Both share similar GI side effects: nausea, vomiting, diarrhea, constipation. These are most common during dose escalation and typically improve over time. Some anecdotal reports suggest tirzepatide causes slightly more nausea at equivalent escalation stages, but clinical trial discontinuation rates were similar between both drugs.
Reconstitution
Both are reconstituted identically with bacteriostatic water. Semaglutide vials are typically smaller (2–10 mg), while tirzepatide vials come in larger sizes (5–30 mg). Use our calculators above to get exact BAC water and syringe measurements for each.
Safety & Track Record
Semaglutide has been on the market longer (Ozempic approved 2017, Wegovy 2021) and has more long-term safety data including cardiovascular outcome trials showing reduced major cardiac events. Tirzepatide (Mounjaro 2022, Zepbound 2023) is newer with less long-term data but shows a clean safety profile so far.
⚖️ The Verdict
Tirzepatide produces greater average weight loss, but semaglutide has a longer safety track record. If maximizing weight loss is the priority and your provider offers it, tirzepatide has the edge. If you prefer a more established option with cardiovascular outcome data, semaglutide is the proven choice. Many practitioners start with semaglutide and switch to tirzepatide if the response plateaus.
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