Semaglutide vs liraglutide

Weekly against daily: how much does the newer drug add, and what does the older one still offer?

Direct head-to-head trial exists
In one paragraphSemaglutide produces roughly two and a half times the weight loss of liraglutide in the one trial that compared them directly: 15.8% against 6.4% at 68 weeks in STEP 8. Both are grade A, both are approved for obesity and type 2 diabetes, and both have a cardiovascular outcomes trial. Liraglutide's remaining advantages are that it is generic, cheaper, dosed daily so it clears faster, and has fifteen years of use behind it.

Side by side

A SemaglutideA Liraglutide
LYO grade (weight)AA
Head-to-head weight loss, 68 wkSTEP 8, n=338, open-label−15.8%−6.4%
Own placebo-controlled trial−14.9% at 68 wk (STEP 1, n=1,961)−8.0% at 56 wk (SCALE, n=3,731)
DosingOnce weeklyOnce daily
Cardiovascular outcomes trial20% MACE reduction vs placebo in obesity without diabetes (SELECT, n=17,604)13% MACE reduction vs placebo in type 2 diabetes (LEADER, n=9,340)
Stopped for adverse events (head-to-head)STEP 83.2%12.6%
Generic availableNoYes (US 2024–2025, EU 2024)
Approved for adolescentsYes (12+)Yes (12+)
First approval20172009
Verdict

Semaglutide, by a wide margin, on the outcome people take these drugs for. Liraglutide is the value option and the one with the longest safety record.

What the head-to-head showed

STEP 8 randomised 338 adults with overweight or obesity to semaglutide 2.4 mg weekly, liraglutide 3.0 mg daily, or placebo for 68 weeks. Semaglutide produced 15.8% weight loss, liraglutide 6.4%, placebo 1.9%. Seven in ten on semaglutide lost at least 10% of body weight; a quarter on liraglutide did.

The trial was open-label between the two active drugs, which matters little for a bathroom scale, and both drugs were at their full obesity doses.

Why the gap is so large

Both drugs act on the same receptor. The difference is exposure: semaglutide's albumin-binding side chain and amino-acid substitutions give it a half-life of about a week and steady receptor activation; liraglutide lasts about thirteen hours, with a daily peak and trough. More constant appetite suppression appears to be what the extra nine percentage points are made of.

Where liraglutide still makes sense

Price: it is the only GLP-1 obesity drug with generics. Familiarity: it has been prescribed since 2009 and its rare side effects are as well mapped as any drug in the class. Reversibility: a daily drug is out of the body within days if it is not tolerated. And in type 2 diabetes it has its own cardiovascular outcomes trial, LEADER, with a 22% reduction in cardiovascular death.

Tolerability does not favour it: in STEP 8, four times as many people stopped liraglutide as semaglutide for adverse events.

Questions people actually ask

Is liraglutide a weaker version of semaglutide?
Pharmacologically, yes — same receptor, shorter exposure. Clinically, it produces less than half the weight loss in the head-to-head trial.
Is liraglutide safer?
Not in the trial data: more people stopped it for side effects than semaglutide in STEP 8. Its advantage is a longer history of use, not a milder profile.
Which is cheaper?
Liraglutide, by a wide margin, since generics reached the US and EU markets in 2024–2025. Price varies by country and payer.

References

  1. 1
  2. 2
  3. 3
  4. 4