Semaglutide
A once-weekly GLP-1 agonist that lowers appetite, slows the stomach and improves blood sugar.
FDA-approved: Wegovy injection and Wegovy tablets (weight), Ozempic and Rybelsus (type 2 diabetes).
Used for
- Weight loss
- Type 2 diabetes
- Lower heart attack and stroke risk in obesity
- Fatty liver, sleep apnea (studied)
How it works
Mimics the gut hormone GLP-1 at receptors in the brain, pancreas and stomach: more fullness, less food noise, more insulin when glucose is high.
Half-life: about 1 week
What the research shows
- STEP 1 (68 weeks): 2.4 mg weekly lost 14.9% of body weight vs 2.4% on placebo.
- SELECT: in 17,604 adults with obesity and heart disease, major cardiac events fell 20%.
- In the STEP 1 extension, people regained about two-thirds of the lost weight within a year of stopping.
- OASIS 4 (oral 25 mg once daily, 64 weeks, 307 adults without diabetes): 13.6% weight loss vs 2.2% on placebo; stomach side effects in 74% vs 42%. Oral 25 mg was FDA-approved for weight in December 2025 (Wegovy tablets).
Dosing
Dosing isn’t listed on the public site. In the app, each published option is shown with its source (a drug label, a clinical guideline, a trial or community reports) and can be turned into a protocol you review.
Work out the units to draw for your vial →Side effects
- Nausea, especially after a dose step
- Constipation or diarrhea
- Reflux, burping
- Lower appetite and thirst: dehydration risk
Cautions
- Not for anyone with a personal or family history of medullary thyroid cancer or MEN2.
- Pancreatitis and gallbladder problems are uncommon but reported; severe belly pain needs urgent care.
- Rapid weight loss costs muscle too: keep protein high and keep lifting.
- Stop before planned surgery or sedation per your doctor (slower stomach emptying).
Storage
Unmixed or unopened: Pens and prefilled syringes: fridge (2–8 °C) in the carton until the expiry date. Never freeze; protect from heat and light.
Mixed or in use: A pen in use keeps 56 days at room temperature (15–30 °C) or in the fridge; cap on, needle off. A prefilled syringe may stay out at 8–30 °C for up to 28 days if needed.
From the Ozempic (Novo Nordisk) label.
Stability once mixed
Built to last, with a fatty-acid side chain and a modified backbone. The pen is labelled 56 days in use, even at room temperature. A vial you mix yourself is a different formulation, so that is the pen’s number, not yours.
Heat, shaking, freezing a mixed vial, light and many needle punctures all speed breakdown. Toss it if it turns cloudy, grows specks or changes color.
Interactions
With insulin or a sulfonylurea it can cause low blood sugar; the label suggests considering a lower dose of those drugs when starting.
It slows stomach emptying, which could change how pills are absorbed. The label found no clinically relevant effect on the drugs tested but advises caution with oral medicines.
Oral semaglutide raised levothyroxine exposure by 33% in an interaction study; the label advises extra monitoring for pills with a narrow safe range.
Not a full list. Tell your doctor and pharmacist everything you take.
More in Weight & metabolic
Reference only, not medical advice. Written for this app from the cited research. Doses marked community-reported are not from trials.