Section 01
What it's used for
Approved Diabetes Treatment
FDA-approved for blood sugar control in type 2 diabetes (Ozempic, Rybelsus). The SUSTAIN trials (1-10) showed it lowered HbA1c by 1.5-1.8 percentage points more than comparison drugs; SUSTAIN-6 found a 26% drop in major heart events.
▸Clinical wording
Semaglutide is FDA-approved for glycemic control in type 2 diabetes (Ozempic, Rybelsus). The SUSTAIN clinical trial program (SUSTAIN 1-10) demonstrated superior HbA1c reduction of 1.5-1.8% versus comparators. SUSTAIN-6 showed 26% reduction in major adverse cardiovascular events (MACE), establishing cardiovascular benefit.
Approved for Weight Management
Approved as Wegovy (2.4 mg weekly) for adults with a BMI of 30+, or 27+ with a weight condition. In the STEP 1 trial, it produced 15-17% body weight loss, plus gains in heart-metabolism risk, sleep apnea, and physical function.
▸Clinical wording
Approved as Wegovy (2.4 mg/week) for adults with BMI ≥30 or ≥27 with weight-related comorbidity. The STEP trial program demonstrated 15-17% body weight reduction (STEP 1), with significant improvements in cardiometabolic risk factors, sleep apnea severity, and physical function.
Cuts Major Heart Events
In the 2023 SELECT trial, 2.4 mg weekly cut major heart events by 20% in overweight or obese adults without diabetes, showing the benefit does not depend on blood sugar control. This led to an expanded, heart-focused approved use.
▸Clinical wording
The SELECT trial (2023) demonstrated that semaglutide 2.4 mg/week reduced MACE by 20% in overweight/obese adults without diabetes — establishing benefit independent of glycemic effects. This led to expanded cardiovascular indications.
Studied for Liver Disease
In the Phase 3 ESSENCE trial, 62.9% of patients on semaglutide saw their liver inflammation (MASH) resolve, versus 34.3% on placebo. This use is still under regulatory review and is not yet a formally approved indication.
▸Clinical wording
Phase 3 trials (ESSENCE) have demonstrated significant improvement in metabolic dysfunction-associated steatohepatitis (MASH), with resolution of steatohepatitis in 62.9% of semaglutide-treated patients versus 34.3% on placebo. The indication is under regulatory review.
Slows Kidney Disease
In the FLOW trial, people with type 2 diabetes and chronic kidney disease who took semaglutide had a 24% slower progression of kidney disease — a notable finding for protecting kidney function over the long term.
▸Clinical wording
The FLOW trial demonstrated 24% reduction in kidney disease progression in patients with type 2 diabetes and CKD, representing a major advance in nephroprotection.
Missed Alzheimer's Trial Goal
Based on earlier lab findings of reduced brain inflammation and amyloid buildup, Phase 3 trials (evoke/evoke+) tested a 14 mg oral dose in early Alzheimer's disease. The trials missed their goal: the drug did not slow disease progression.
▸Clinical wording
Phase 3 trials (evoke/evoke+) tested oral semaglutide 14 mg for neuroprotection in early symptomatic Alzheimer's disease, based on earlier preclinical evidence of reduced neuroinflammation and amyloid burden. These trials did not meet their primary endpoint: oral semaglutide was not efficacious in slowing clinical progression of the disease.
Section 02
Mechanism of Action
Docking onto the gut hormone receptor
- Semaglutide binds the receptor for the gut hormone GLP-1 and switches it on.
- That receptor sits on insulin-producing pancreatic cells and in the brain, gut, heart and kidneys.
- Switching it on raises an internal messenger (cAMP) and starts two signalling cascades inside the cell.
▸Clinical wording
GLP-1 Receptor Activation
Semaglutide binds to and activates the GLP-1 receptor (GLP-1R), a class B G-protein coupled receptor expressed in pancreatic beta cells, the central nervous system, gastrointestinal tract, heart, and kidneys. Receptor activation stimulates adenylyl cyclase, increasing intracellular cAMP levels and activating protein kinase A (PKA) and Epac2 signaling cascades.
Insulin released only when sugar is high
- In insulin-producing pancreatic cells the receptor strengthens the insulin release that glucose already triggers.
- It works by closing potassium channels, changing the cell's charge and letting calcium flow in.
- Because the effect depends on glucose, low-blood-sugar risk is much lower than with sulfonylurea drugs.
- Semaglutide also suppresses glucagon release from neighbouring cells, again in a glucose-dependent way.
▸Clinical wording
Glucose-Dependent Insulin Secretion
In pancreatic beta cells, GLP-1R activation potentiates glucose-stimulated insulin secretion (GSIS) through closure of ATP-sensitive potassium channels, membrane depolarization, and calcium influx. This glucose-dependent mechanism significantly reduces hypoglycemia risk compared to sulfonylureas. Simultaneously, semaglutide suppresses glucagon secretion from alpha cells in a glucose-dependent manner.
Dialling down hunger in the brain
- Weight loss runs mainly through receptors in brain regions that control energy balance.
- It switches on appetite-suppressing neurons while switching off hunger-driving ones in the hypothalamus.
- It also acts on a brainstem relay that amplifies fullness signals arriving along the vagus nerve.
▸Clinical wording
Central Appetite Regulation
Semaglutide's weight loss effects are primarily mediated through GLP-1 receptors in hypothalamic and hindbrain regions controlling energy homeostasis. It activates POMC/CART neurons in the arcuate nucleus while inhibiting NPY/AgRP neurons, reducing hunger signaling. It also acts on the nucleus tractus solitarius to enhance satiety signals from vagal afferents.
Food leaves the stomach more slowly
- The peptide delays stomach emptying through both brain-based and local mechanisms.
- Food staying longer adds to fullness after meals and lowers how much is eaten.
- This effect is strongest early in treatment and partly fades over time.
▸Clinical wording
Gastric Motility
The peptide delays gastric emptying through both central and peripheral mechanisms, contributing to postprandial satiety and reduced food intake. This effect is most pronounced during initial treatment and partially attenuates over time.
Possible protection of insulin cells
- Preclinical evidence suggests semaglutide helps insulin-producing cells multiply and resist programmed cell death.
- It may also let new insulin cells form from precursor cells in the pancreatic ducts.
- These findings are preclinical, so any effect on the decline seen in type 2 diabetes stays unproven.
▸Clinical wording
Beta Cell Preservation
Preclinical evidence suggests semaglutide promotes beta cell proliferation, inhibits apoptosis, and may enhance beta cell neogenesis from ductal progenitor cells — potentially modifying the progressive decline in beta cell function characteristic of type 2 diabetes.
Section 03
Biological Pathways
- cAMP/PKA Signaling CascadeGαs-coupled adenylyl cyclase raises cAMP, activating PKA and Epac2; PKA phosphorylates CREB, driving transcription of insulin and beta cell survival genes, while Epac2 potentiates insulin granule exocytosis.
- PI3K/Akt PathwayGLP-1R activation engages PI3K/Akt signaling, promoting beta cell survival by inactivating pro-apoptotic factors (Bad, GSK-3β) and mediating GLUT2 expression and glucose metabolism in beta cells.
- MAPK/ERK PathwayERK1/2 activation downstream of GLP-1R stimulates beta cell proliferation and differentiation, cross-talking with Wnt signaling via GSK-3β inhibition to expand beta cell mass in preclinical studies.
- Central Melanocortin SystemIn the hypothalamus, GLP-1R signaling activates the melanocortin pathway, stimulating POMC neurons to produce α-MSH, which acts on MC4R to suppress appetite.
Section 04
Dosage Information
His-Aib-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys(C18 fatty diacid)-Glu-Phe-Ile-Ala-Trp-Leu-Val-Arg-Gly-Arg| Route / system | Context | Range studied | Limitation |
|---|---|---|---|
| Subcutaneous — obesity label | Wegovy injection, also lowers heart risk | 0.25 mg weekly, up every 4 weeks via 0.5, 1 and 1.7 to 2.4 mg at week 17, then 7.2 mg — about 27–34 µg/kg a week at 70–90 kg | 2.4 mg ends a 16-week supervised ramp, not a starting point: without it the gut upset is intolerable. Two-thirds of lost weight returned a year after stopping. |
| Subcutaneous — diabetes label | Ozempic injection, also heart and kidney outcomes | 0.25 mg weekly for 4 weeks, then 0.5 and 1 mg in 4-week steps; upkeep 0.5, 1 or 2 mg a week, ceiling 2 mg — 22–29 µg/kg at 70–90 kg | Blood-sugar control and heart and kidney outcomes in type 2 diabetes. The 2 mg ceiling sits below the weight-loss doses; Ozempic was never approved for weight. |
| Oral — obesity label | Wegovy tablets, approved December 2025 | 1.5 mg daily for 30 days, then 4 mg, then 9 mg, and 25 mg from day 91 — about 280–360 µg/kg a day at 70–90 kg, or 175 mg a week | A milligram swallowed is not a milligram injected: 25 mg a day gave 13.6% weight loss over 64 weeks, close to what 2.4 mg a week injected does. |
| Oral — diabetes label | Rybelsus and Ozempic tablets — two strengths | Rybelsus: 3 mg daily 30 days, 7 mg from day 31, max 14 mg. Ozempic tablets: 1.5, then 4 mg from day 31, max 9 mg. Both fasting | Not interchangeable milligram for milligram, the label says. Absorption hangs on the fast: 120 mL of water at most, nothing else for 30 minutes. |
| Subcutaneous — self-administration | Compounded or unapproved vials, outside any label | No dose of its own: label figures poured into vials of unverified strength; "microdosing", a quarter of a dose, has no protocol | Doses 5 to 20 times the intended amount were reported — milligrams read as syringe units on vials with no dose stops; poison centres saw 10-fold errors. |
Results
Syringe Fill Level (100u syringe)
Set positive values for: Recommended dose per kg.
Research Use Only. This information is for educational and research purposes only. Not intended for medical advice or self-medication.
Section 05
Protocols
- Protocol 01
Semaglutide Weight Loss - Beginner
FDA-approved GLP-1 protocol for safe, effective weight loss. Ideal for first-time users.
- Focus
- Weight Loss
- Level
- Beginner
- Duration
- 6+ months
Section 06
Stability & Storage
Storing the product
Injectable semaglutide (Ozempic, Wegovy) is kept refrigerated at 2-8°C (36-46°F) before first use. Rybelsus tablets are kept at room temperature (20-25°C) inside their original blister packaging to protect them from moisture. The fatty-acid side chain binds strongly to albumin, which shields the peptide from enzymatic breakdown and supports its long stability.
After opening
Once an injection pen is in use, it can be kept at room temperature (up to 30°C/86°F) or refrigerated, and used within 56 days (8 weeks). Reconstituted research-grade semaglutide is kept at 2-8°C, used within 30 days, and should not go through repeated freeze-thaw cycles.
Section 07
Side Effects & Precautions
Semaglutide's side effects are dominated by gastrointestinal symptoms during dose escalation, plus several boxed and organ-specific warnings that define who should not use it.
Digestive and injection-site effects
- Nausea (20-44%), vomiting (6-24%), and diarrhea (8-30%) are the most frequent adverse effects, transient during dose escalation and diminishing over 4-8 weeks.
- Constipation (5-24%) and abdominal pain are also common.
- Mild injection-site reactions — redness, itching, swelling — occur in about 0.2-1% of patients and are generally self-limiting.
Gallbladder and pancreas events
- Gallstones (cholelithiasis) and gallbladder inflammation (cholecystitis) occur at higher rates than placebo (1.5-2.6%), likely linked to rapid weight loss.
- Acute pancreatitis has been reported rarely (<0.5%); semaglutide is contraindicated in patients with a history of pancreatitis.
Thyroid C-cell tumor warning
A boxed warning exists based on rodent studies showing a risk of thyroid C-cell tumors; relevance to humans is uncertain. Semaglutide is contraindicated in patients with a personal or family history of medullary thyroid carcinoma or MEN2 syndrome.
Hypoglycemia
When used with insulin or sulfonylurea drugs, the risk of hypoglycemia (low blood sugar) increases. As monotherapy, significant hypoglycemia is rare because the mechanism is glucose-dependent.
Section 08
Regulatory Status
It carries FDA approval under three brand names, clearance from over 100 national regulators, and an expanding label rather than a shrinking one.
FDA / United States
Approved under three brand names
Ozempic (0.5, 1 and 2 mg injection) treats type 2 diabetes, approved 2017; Rybelsus, the oral tablet form, approved 2019; Wegovy (2.4 mg injection) treats chronic weight management, approved 2021. In 2024 the FDA expanded Wegovy's label to cardiovascular risk reduction based on the SELECT trial.
EMA and other regulators
Approved in 100+ countries
Semaglutide holds marketing authorisation from the EMA, Health Canada, Australia's TGA, and national regulators across more than 100 countries, generally for type 2 diabetes and weight management under the same three brand names.
Compounded versions
Being phased out in the US
As supply shortages eased, the FDA proposed on 30 April 2026 removing semaglutide from the 503B outsourcing-facility bulks list, which would end large-scale compounded copies once finalised; the public comment period closed 29 June 2026.
Controlled-substance status
Not a controlled substance
Neither the FDA nor the DEA classifies semaglutide as a controlled substance in the United States, and prescribers need no special DEA registration to write for it.
WADA
On the Monitoring Program, not banned
WADA has tracked semaglutide on its Monitoring Program since 2024, with tirzepatide markers added from 1 January 2026; monitored substances carry no sanction and remain legal in and out of competition unless WADA later moves them to the Prohibited List.
Approval covers the specific FDA-cleared brands, doses and indications — not every compounded or off-label version sold under the same name. Regulatory status differs between jurisdictions and changes over time; check the current documents of your own regulator before relying on any of this.
Section 09
Research Studies
- [1]Discovery of the Once-Weekly Glucagon-Like Peptide-1 (GLP-1) Analogue SemaglutideLau J, Bloch P, Schäffer L, et al. · Journal of Medicinal Chemistry · 2015
- [2]The Discovery and Development of Liraglutide and SemaglutideKnudsen LB, Lau J. · Frontiers in Endocrinology · 2019
- [3]Effects of semaglutide on beta cell function and glycaemic control in participants with type 2 diabetes: a randomised, double-blind, placebo-controlled trialKapitza C, Dahl K, Jacobsen JB, et al. · Diabetologia · 2017
- [4]Semaglutide lowers body weight in rodents via distributed neural pathwaysGabery S, Salinas CG, Paulsen SJ, et al. · JCI Insight · 2020
- [5]Effects of once-weekly semaglutide on appetite, energy intake, control of eating, food preference and body weight in subjects with obesityBlundell J, Finlayson G, Axelsen M, et al. · Diabetes, Obesity and Metabolism · 2017
- [6]The effect of semaglutide 2.4 mg once weekly on energy intake, appetite, control of eating, and gastric emptying in adults with obesityFriedrichsen M, Breitschaft A, Tadayon S, et al. · Diabetes, Obesity and Metabolism · 2021
- [7]Once-Weekly Semaglutide in Adults with Overweight or ObesityWilding JPH, Batterham RL, Calanna S, et al. · New England Journal of Medicine · 2021
- [8]Semaglutide and Cardiovascular Outcomes in Patients with Type 2 DiabetesMarso SP, Bain SC, Consoli A, et al. · New England Journal of Medicine · 2016
- [9]Semaglutide and Cardiovascular Outcomes in Obesity without DiabetesLincoff AM, Brown-Frandsen K, Colhoun HM, et al. · New England Journal of Medicine · 2023
- [10]Effects of Semaglutide on Chronic Kidney Disease in Patients with Type 2 DiabetesPerkovic V, Tuttle KR, Rossing P, et al. · New England Journal of Medicine · 2024
Section 10
Frequently Asked Questions
It is the same active substance under different brand names: Ozempic is the injection for type 2 diabetes (2017), Rybelsus the tablet for diabetes (2019), Wegovy the injection for weight management (2021). What differs is the indication and the dose ceiling, not the molecule — Ozempic tops out at 2 mg a week while the Wegovy schedule climbs to 2.4 mg and beyond. Ozempic was never approved for weight loss.
No. Insulin lowers blood sugar directly; semaglutide is an analogue of GLP-1, a gut hormone the body makes itself. It increases your own insulin release in response to food, suppresses glucagon and slows gastric emptying. Because it works glucose-dependently it rarely causes hypoglycaemia on its own — the risk rises when it is combined with insulin or a sulfonylurea.
The effect builds over months because the dose is escalated in steps — the Wegovy ramp takes about 16 weeks, and 2.4 mg is the end of that ladder rather than a starting point. In the oral trial 25 mg a day produced 13.6% of body weight over 64 weeks, close to what 2.4 mg a week injected achieves.
The weight largely comes back: about two-thirds of what was lost had returned a year after stopping. The drug changes appetite and gastric emptying only while it is present, and those effects end with it. Its half-life is about a week, so it clears the blood over roughly 5 to 7 weeks.
Digestion takes the brunt: nausea in 20 to 44%, plus vomiting, diarrhoea and constipation, mostly during dose escalation and easing over 4 to 8 weeks — slower titration reduces them markedly. Less often there are gallstones (1.5 to 2.6%, linked to rapid weight loss) and pancreatitis (under 0.5%). A separate boxed warning covers thyroid C-cell tumours: it rests on rodent studies and its relevance to humans is unsettled, but the drug is contraindicated with a personal or family history of medullary thyroid carcinoma or MEN2.
No — it is not used in pregnancy. There are no data in pregnant women and animal studies showed harm to the fetus at exposures close to therapeutic ones. The Wegovy label directs stopping at least two months before a planned pregnancy, precisely because the drug clears slowly. There are no data on breastfeeding either.
Before first use, yes — 2–8 °C. Rybelsus tablets are different: room temperature, in the original blister, because they are sensitive to moisture. Once a pen is in use it can stay at room temperature up to 30 °C or in the fridge, and should be used within 56 days.
No: GLP-1 receptor agonists are not on the WADA Prohibited List, and no therapeutic use exemption is required for them. Semaglutide has been on the monitoring programme since 2024, where laboratories track patterns of use without sanctions, and that monitoring was in force at the 2026 Winter Games. Whether to prohibit the class is under discussion ahead of the 2028 Games.