Liraglutide is the older, once-daily member of the GLP-1 family — the drug that helped prove the whole class works before the weekly blockbusters arrived. It is fully approved, sold as Saxenda (for weight) and Victoza (for type 2 diabetes). Its defining quirk is the schedule: unlike weekly semaglutide, liraglutide is injected once a day.
In plain terms: the original modern GLP-1 drug — same idea as semaglutide, but it clears faster, so it is a daily shot.
(The figure compares half-lives across compounds — liraglutide's short one is why it is dosed daily rather than weekly.)
What it is
Liraglutide is a GLP-1 receptor agonist. GLP-1 (glucagon-like peptide-1) is a gut hormone released after meals that lowers appetite, slows how fast the stomach empties, and helps the pancreas release insulin. An "agonist" is a molecule that switches a receptor on — so liraglutide switches on the GLP-1 receptor, imitating the natural hormone1.
It was developed by Novo Nordisk and reached the market well before semaglutide. The same molecule is sold under two brand names:
- Victoza — the type 2 diabetes version (studied up to 1.8 mg daily).
- Saxenda — the higher-dose weight-management version (studied up to 3.0 mg daily).
Same drug, different doses and approved uses.
The mechanism: one receptor
Liraglutide is a single-target drug — it activates only the GLP-1 receptor. That is one lever, compared with the two of survodutide (GLP-1 + glucagon) or the three of retatrutide.
Through that one receptor it:
- lowers appetite and increases fullness, so people eat less;
- slows stomach emptying, so meals feel more filling for longer;
- boosts glucose-dependent insulin release, which lowers blood sugar.
In plain terms: it pulls the same single lever as semaglutide — just for a shorter time per dose.
Pharmacokinetics: why once a day
Here is the heart of the liraglutide story. Its half-life — the time for half a dose to clear the body — is about 13 hours3. That is dramatically shorter than weekly GLP-1 drugs.
| Drug | Reported half-life | Dosing rhythm |
|---|---|---|
| Liraglutide | ~13 hours | Once daily |
| Semaglutide | ~7 days | Once weekly |
| Tirzepatide | ~5 days | Once weekly |
Liraglutide uses a fatty-acid chain that binds albumin (a blood protein) to slow its breakdown — the same class of trick as the weekly drugs, but tuned to last a day rather than a week. A 13-hour half-life is not long enough to cover a full week, so it is dosed once daily to keep levels steady.
In plain terms: shorter half-life means more frequent dosing. That single number is why liraglutide is a daily injection and semaglutide is not.
What the trials actually found
Liraglutide has one of the longest, most solid evidence bases in this class — including a landmark cardiovascular-outcomes trial, the gold standard for proving a drug protects the heart. Note the model in each row.
| Trial | People | Key result | Year |
|---|---|---|---|
| Pi-Sunyer et al. — SCALE (phase 3)1 | 3,731 adults with overweight/obesity | ~8% body-weight loss at 56 weeks on 3.0 mg vs ~2.6% on placebo; 63% lost 5% or more | 2015 |
| Marso et al. — LEADER (phase 3)2 | 9,340 adults with type 2 diabetes | Cut major cardiovascular events by 13% and cardiovascular death by 22% vs placebo | 2016 |
In plain terms: in the big weight trial, the average person on the 3.0 mg dose lost about 8% of body weight over roughly a year1. And in a very large heart-outcomes trial, liraglutide didn't just lower blood sugar — it reduced heart attacks, strokes, and cardiovascular deaths in people with diabetes2. That cardiovascular evidence is a big part of why liraglutide is trusted.
Practical notes and handling
Liraglutide was studied as a subcutaneous (under-the-skin) once-daily injection, with the dose raised gradually over the first weeks — the standard step-up used to ease early nausea. This describes the trials for education only, not how to use anything. The most common reported side effects were gastrointestinal — nausea, diarrhoea, and vomiting — usually strongest early and easing over time.
Honest limitations
Liraglutide is a fully approved medicine with years of real-world use behind it — that is its strength. Its honest limitation is comparative: the newer weekly drugs generally produce more weight loss. Semaglutide (~15% in its trial) and tirzepatide (~20%+) both outperform liraglutide's ~8% on weight, and their once-weekly schedule is more convenient than a daily shot. So liraglutide's role has narrowed as the class has advanced, even as its safety record and proven heart benefit keep it relevant. This page explains what it is and what the trials showed — not how to use it — and takes no position on sourcing.
Latest research
- The SCALE and LEADER trials remain the foundation: ~8% weight loss over 56 weeks1, and a clear cardiovascular benefit in diabetes2 — the latter a milestone that shaped how the whole GLP-1 class is judged.
- A pediatric approval extended liraglutide to adolescents with obesity, based on later SCALE studies in younger people — broadening who it is studied in.
- The competitive picture has shifted. Weekly semaglutide and tirzepatide, and combinations like CagriSema, now set the pace on weight loss, positioning liraglutide as the well-established, shorter-acting reference point. We update this section as new comparisons report.
The short version
Liraglutide is the older, once-daily GLP-1 receptor agonist — sold as Saxenda for weight and Victoza for diabetes. Its ~13-hour half-life is why it is a daily rather than weekly injection. It produced ~8% weight loss in the SCALE trial and cut cardiovascular events in the LEADER trial, and it is fully approved — though newer weekly drugs generally lose more weight. Educational overview only, not medical advice.