Semaglutide
A synthetic analog of human Glucagon-Like Peptide-1 (GLP-1)
A GLP-1 receptor agonist studied for weight management and type 2 diabetes
Semaglutide is a GLP-1 receptor agonist first developed for type 2 diabetes. As of October 2026, it's an FDA-approved prescription medicine from Novo Nordisk, sold as Ozempic and Rybelsus for type 2 diabetes and as Wegovy for weight management and for lowering cardiovascular risk in adults with heart disease and overweight or obesity. Wegovy comes as a weekly injection of up to 7.2 mg (the 7.2 mg Wegovy HD dose was approved in March 2026) and as a 25 mg daily tablet (approved December 2025). In the STEP 1 trial, adults with obesity or overweight lost 14.9% of body weight on average over 68 weeks on 2.4 mg, vs 2.4% on placebo. Research-use vials aren't the approved product, and FDA has warned companies selling semaglutide labeled "for research purposes".
Read the research profile for mechanisms, citations, and safety context before comparing vendors. View the Semaglutide research profile.
Key Benefits
Mechanism of Action
Semaglutide mimics GLP-1, a gut hormone released after eating, and activates GLP-1 receptors. It binds tightly to albumin in the blood, which gives it a half-life of about a week and allows once-weekly injection. GLP-1 receptor activation raises insulin release when blood sugar is high, lowers glucagon release and slows gastric emptying. Semaglutide also acts on appetite centers in the brain, including the hypothalamus, which is thought to drive much of the reduced hunger and earlier fullness (satiety) seen in trials and commonly reported by users.
Dosing Guidelines
Typical Dose
0.25-2.4 mg weekly per the Wegovy label (Wegovy HD: up to 7.2 mg)
Frequency
1x weekly (Wegovy tablets: daily)
Duration
Long-term (label trials ran 64-72 weeks)
Note: The Wegovy label gives semaglutide by subcutaneous injection once a week, starting at 0.25 mg for 4 weeks and stepping up every 4 weeks (0.5, 1 and 1.7 mg) to a maintenance dose of 1.7 or 2.4 mg. Adults who tolerate 2.4 mg for at least 4 weeks may move to 7.2 mg (Wegovy HD, approved March 2026). The label uses this slow step-up to reduce stomach side effects. The Wegovy tablet (approved December 2025) steps up every 30 days from 1.5 mg to 25 mg daily and relies on an absorption enhancer (SNAC), so research vials aren't an oral equivalent. Trial participants also followed a reduced-calorie diet and exercise program. Some forum users describe "microdosing" far below label doses; no trial has tested those doses.
Research & Studies
Our profile of semaglutide's mechanism, trial results, reported doses and side effects, for research purposes.
Read Full ResearchIn 1,961 adults with obesity or overweight and no diabetes, weekly semaglutide 2.4 mg plus a lifestyle program gave mean weight loss of 14.9% at 68 weeks, vs 2.4% on placebo. In a one-year off-treatment extension, participants regained about two-thirds of the weight they had lost.
Read Full ResearchIn 3,297 adults with type 2 diabetes at high cardiovascular risk, heart attack, stroke or cardiovascular death occurred in 6.6% on weekly semaglutide (0.5 or 1 mg) vs 8.9% on placebo over 104 weeks. The later SELECT trial, in adults with heart disease and overweight or obesity, reported a 20% lower risk on 2.4 mg.
Read Full ResearchHow semaglutide (GLP-1 only) and tirzepatide (GIP and GLP-1) differ. In the head-to-head SURMOUNT-5 trial, mean weight loss at 72 weeks was 20.2% on tirzepatide vs 13.7% on semaglutide 1.7-2.4 mg.
Read Full ResearchPotential Side Effects
Reported side effects may include:
- - Nausea, the most common side effect (44% on 2.4 mg vs 16% on placebo in label trials), mostly while the dose is being raised
- - Vomiting, diarrhea, constipation, abdominal pain and bloating (common in trials)
- - Fatigue, especially early on (trials; also user reports)
- - Skin burning or tingling (dysesthesia): 22% at 7.2 mg vs 6% at 2.4 mg (label)
- - Hair loss: 5.8% at 7.2 mg vs 3.3% at 2.4 mg (label), linked to weight loss
- - Rare but serious: pancreatitis and gallbladder disease; boxed warning for thyroid C-cell tumors seen in rodents
This information is for research purposes only. Always consult with a healthcare professional.
Popular Stacking Options
Semaglutide + CJC-1295 / Ipamorelin
Some users add it hoping to limit muscle loss during rapid weight loss, on the theory that raising growth hormone helps preserve lean mass. No study has measured muscle outcomes with these peptides, and none has tested them alongside semaglutide.
Shop this stackSemaglutide + MOTS-c
Some users pair it on the theory that it supports mitochondrial metabolism and energy during a calorie deficit. The MOTS-c data are almost entirely from mice, and no study has tested the combination.
Shop this stackSemaglutide + BPC-157
Some users add it hoping to ease the nausea and gut discomfort common with GLP-1 drugs, based on rodent gut studies. BPC-157 has only small uncontrolled human pilots, and no study has tested this combination.
Shop this stackFrequently Asked Questions
How quickly does Semaglutide work for weight loss?
Users commonly report less appetite within the first few weeks. In trials, weight loss built gradually through the dose step-up (16 weeks in STEP 1) and continued after it: STEP 1 measured 14.9% mean loss at 68 weeks on 2.4 mg. Trial participants also followed a reduced-calorie diet and exercise program, so those results reflect both.
What is the most common side effect and how is it managed?
Nausea. In the Wegovy label trials it affected 44% of people on 2.4 mg vs 16% on placebo, mostly while the dose was being raised. The label's slow step-up (every 4 weeks for injections, every 30 days for tablets) exists to reduce stomach side effects, and it allows a step to be delayed if a dose isn't tolerated. Users commonly describe eating smaller meals and avoiding fatty foods; that's community practice, not something trials tested. Severe or persistent vomiting, stomach pain or signs of dehydration are reasons to see a healthcare professional.
Will I regain the weight if I stop taking Semaglutide?
Trials suggest most people regain much of it. In the STEP 1 extension, participants who stopped semaglutide 2.4 mg and the trial's lifestyle program regained about two-thirds of their lost weight within a year, and most heart and metabolic improvements drifted back toward baseline. In a withdrawal trial described in the Wegovy label, people switched to placebo after 20 weeks gained 6.9% over the next 48 weeks, while those who stayed on semaglutide lost another 7.9%.
Do I still need to diet and exercise while using Semaglutide?
The approved products are labeled for use alongside a reduced-calorie diet and more physical activity, and the major weight-loss trials included a lifestyle program, so their results reflect the drug plus those changes. Semaglutide is thought to make a diet easier to stick to by lowering appetite. No trial has tested it as a replacement for diet changes.
What's the difference between Semaglutide and Tirzepatide?
Semaglutide activates only the GLP-1 receptor. Tirzepatide activates both the GLP-1 and GIP (glucose-dependent insulinotropic polypeptide) receptors. In the SURMOUNT-5 trial (751 adults with obesity, open-label, funded by Lilly), mean weight loss at 72 weeks was 20.2% on tirzepatide vs 13.7% on semaglutide 1.7-2.4 mg. That trial didn't test the newer 7.2 mg semaglutide dose. Both are FDA-approved prescription medicines.
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