Semaglutide vs Tirzepatide
Verdict: Head-to-head trial data (SURMOUNT-5) gives tirzepatide the edge on raw weight loss — roughly 20% versus 14% body weight over 72 weeks — thanks to its dual GIP/GLP-1 action. Semaglutide counters with a longer safety track record, more prescriber familiarity, and often better availability. Many people also simply respond differently to each: non-responders on one sometimes do well on the other.
Side by side
| Semaglutide | Tirzepatide | |
|---|---|---|
| Typical dose | 250 mcg–2.4 mg | 2.5 mg–15 mg |
| Frequency | 1x weekly, titrated up over months | 1x weekly, titrated up |
| Administration | subcutaneous injection | subcutaneous injection |
| Common vials | 2 mg, 5 mg, 10 mg | 5 mg, 10 mg, 15 mg, 30 mg |
| Typical mix | 5 mg + 2 ml water | 10 mg + 2 ml water |
| Units for typical dose | 20 units (500 mcg) | 50 units (2.5 mg) |
One receptor vs two
Semaglutide activates the GLP-1 receptor: slower gastric emptying, higher satiety, better glucose response. Tirzepatide adds GIP receptor agonism on top, which appears to amplify both fat loss and insulin sensitivity while, counterintuitively, improving GI tolerability at equivalent effect levels in trials.
Dosing and titration
Both are weekly subcutaneous injections with slow ramps. Semaglutide climbs 0.25 → 0.5 → 1.0 → 1.7 → 2.4 mg, moving up roughly every 4 weeks. Tirzepatide climbs 2.5 → 5 → 7.5 → 10 → 12.5 → 15 mg on the same rhythm. Note the different scales: 2.5 mg of tirzepatide is a starting dose, while 2.4 mg of semaglutide is the maximum — never carry numbers from one to the other.
Reconstitution math differs
Compounded and research vials of tirzepatide run much larger (10–30 mg) than semaglutide (2–10 mg). With a 30 mg tirzepatide vial in 2 ml of water, each insulin-syringe unit carries 150 mcg — so a misread of 2 units is a 300 mcg error. Double-check concentration on every new vial; the calculator on each peptide page does this instantly.
Can you stack them?
These two are not stacked together — they compete for the same pathway and combining them mainly multiplies GI side effects. The studied combination partner for this class is cagrilintide (an amylin analog), which works through a separate satiety mechanism.
More comparisons
Educational comparison based on commonly published research protocols — not medical advice or an endorsement of any compound.