Wegovy vs Saxenda: The Randomized Trial That Compared Them Directly

Most GLP-1 brand comparisons on this site rely on separate trials run years apart, because no head-to-head randomized trial exists for those pairs. Wegovy and Saxenda are the exception. A real randomized trial compared them directly, and the result is one of the more decisive numbers in this drug class.

Two generations of the same idea

Saxenda — liraglutide 3.0 mg, injected once daily — was FDA-approved for chronic weight management in 2014, the first GLP-1 receptor agonist approved specifically for that purpose. Its own pivotal trial, SCALE Obesity and Prediabetes, tested it against placebo in adults with obesity or overweight plus a weight-related condition². Wegovy — semaglutide 2.4 mg, injected once weekly — followed in 2021, a newer molecule built on the same receptor target with a longer half-life that allows once-weekly rather than once-daily dosing.

STEP 8: the actual head-to-head

In 2022, a randomized, 68-week phase 3 trial — STEP 8 — put the two drugs against each other directly in adults with overweight or obesity, rather than relying on separate placebo-controlled trials run years apart¹. The result was not close. Mean weight change was -15.8% with semaglutide versus -6.4% with liraglutide — a 9.4 percentage point difference. Participants on semaglutide were far more likely to reach major weight-loss thresholds: 70.9% reached at least 10% weight loss versus 25.6% on liraglutide (odds ratio 6.3), and 38.5% reached at least 20% versus just 6.0% (odds ratio 8.2).

The tolerability gap that number hides

Weight loss wasn't the only thing that separated the two drugs in STEP 8. Treatment discontinuation for any reason was 13.5% with semaglutide versus 27.6% with liraglutide — more than double. Reported rates of GI adverse events were similar between groups (84.1% vs 82.7%), so the discontinuation gap doesn't appear to be driven by a worse side-effect profile on liraglutide; it more plausibly reflects the daily-injection burden and the smaller reward for staying on it. A drug over twice as likely to be abandoned mid-trial is a tolerability signal worth weighing alongside the weight-loss numbers, not a footnote to them. The FDA-label side-effect specifics for GLP-1 drugs generally are in GLP-1 side effects.

Why this comparison still matters in 2026

Saxenda isn't the drug most new patients start on anymore — Wegovy and Zepbound dominate current prescribing, and our board is built around the newer molecules. But Saxenda remains FDA-approved, still prescribed, and sometimes the drug an insurer will cover when a newer option isn't on formulary. If a provider or your coverage steers you toward liraglutide, STEP 8 is the real evidence for what to expect relative to semaglutide, rather than a guess.

How to decide

On randomized trial evidence — not a retrospective estimate — semaglutide (Wegovy) outperforms liraglutide (Saxenda) on both average weight loss and how many people stay on treatment long enough to get there. That makes Wegovy the better-evidenced default when both are genuinely available to you. Saxenda remains a reasonable option when it's what your coverage actually pays for, or if a prescriber has a specific clinical reason to start there. For the weekly-injection alternative built on a different receptor mechanism entirely, see semaglutide vs tirzepatide; for the brand-name version of the semaglutide question, Wegovy vs Zepbound. CoreAge Rx and the semaglutide board are where to compare providers carrying the newer molecule, and the rest of the Desk's sourced evidence is in the research library.