Semaglutide: Dosing, Side Effects, and Real-World Data
The molecule behind Wegovy and compounded semaglutide — mechanism, dosing, and what the trials show.

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Educational, not medical advice. Semaglutide is a prescription medicine. Compounded semaglutide is prepared by licensed 503A and 503B compounding pharmacies. Talk to a clinician about dosing.
Semaglutide is the most-prescribed GLP-1. It's the molecule behind Ozempic® (for type 2 diabetes) and Wegovy® (for weight management), and it's also the one most often compounded.
How does semaglutide work?
Semaglutide is a GLP-1 receptor agonist — it mimics your gut's GLP-1 hormone but resists the enzyme that normally breaks it down, so it stays active long enough to reduce appetite, slow stomach emptying, and improve blood-sugar control once a week.
How is semaglutide dosed?
In the branded products, semaglutide starts low and ramps up over several weeks to let your body adjust, which reduces nausea. The exact titration schedule and target dose are set by your clinician based on your goal — this is not a dosing guide.
What do the semaglutide trials show?
- Around 15% average weight loss over ~68 weeks in the weight-loss trial (Wegovy®).
- Meaningful A1c reduction in type 2 diabetes (Ozempic®).
- Cardiovascular benefit shown in the large SELECT trial (for the diabetes formulation).
- Most common side effects: nausea, GI upset — usually early and dose-related.
Is compounded semaglutide the same as Wegovy, and can you still get it?
For several years a large share of the semaglutide people actually took was compounded, because branded Wegovy® supply was short. That window has closed. The FDA declared the semaglutide shortage resolved in February 2025, and the deadlines to stop compounding under the shortage exemption passed that spring — April 22 for 503A pharmacies, May 22 for 503B outsourcing facilities.
Compounded semaglutide is not FDA-approved and is not interchangeable with Wegovy® or Ozempic®. A 503A pharmacy can still prepare a patient-specific formulation where the prescriber documents a clinically significant difference from the approved product for that patient, but that is a narrow exception rather than a general supply channel. Ask any provider, directly, which product you would be getting and what the documented basis is.
Common questions about semaglutide
- How does semaglutide work?
- It is a GLP-1 receptor agonist. It mimics your gut's GLP-1 hormone but resists the enzyme that breaks it down, so it stays active long enough to reduce appetite, slow stomach emptying, and improve blood-sugar control with once-weekly dosing.
- How much weight do you lose on semaglutide?
- Around 15% of body weight on average over about 68 weeks in the weight-loss trial (Wegovy). It also reduces A1c in type 2 diabetes (Ozempic) and showed cardiovascular benefit in the large SELECT trial.
- Is compounded semaglutide the same as Wegovy?
- No. Compounded semaglutide is not FDA-approved and is not interchangeable with Wegovy or Ozempic. The FDA declared the semaglutide shortage resolved in February 2025, and the shortage-based compounding exemption has ended; a patient-specific preparation now requires a prescriber-documented clinically significant difference.
Related reading
How it measures up against tirzepatide in the only trial that compared them directly: semaglutide vs. tirzepatide. What every route actually costs: the GLP-1 Cost Index. Whether it reaches an infant through breast milk: semaglutide and breastfeeding.
También en español
Semaglutida: precio y dónde conseguirla y semaglutida vs. tirzepatida.
Bottom line
Semaglutide is a real, well-studied medicine with strong weight-loss and metabolic data — all of it generated with the approved product. Know whether you are getting brand or compounded, and if compounded, what the documented clinical reason is. This is information, not a prescription.
Want this handled for you?
LunaRx — clinician-led GLP-1 care with a plan to come off
LunaRx connects you with a licensed clinician for an online evaluation. Depending on your state that is a live or a store-and-forward visit. If the clinician determines a GLP-1 is appropriate for you, a licensed pharmacy dispenses it — with a plan to come off when you’re ready. The prescribing decision is the clinician’s alone, and approval is not guaranteed.
Sources
Primary sources for the claims in this article. Trial results are reported as published; prescribing information is the authoritative reference for dosing and safety.
- 1.STEP 1: Once-Weekly Semaglutide in Adults with Overweight or Obesity
Wilding JPH, et al. · New England Journal of Medicine · 2021
Mean weight change of −14.9% with semaglutide 2.4 mg versus −2.4% with placebo at 68 weeks.
- 2.SELECT: Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes
Lincoff AM, et al. · New England Journal of Medicine · 2023
20% relative reduction in major adverse cardiovascular events (8.0% to 6.5% absolute) with semaglutide 2.4 mg.
- 3.WEGOVY (semaglutide) injection — full prescribing information
DailyMed, U.S. National Library of Medicine · 2026
Boxed warning for thyroid C-cell tumors, MTC/MEN 2 contraindications, and the labeled adverse-reaction profile — including hair loss in 3.3% of adults on 2.4 mg (4% of women, 0.9% of men) versus 1% on placebo. The June 2026 revision warns about diabetic retinopathy complications but does not list NAION. Verified 2026-09-29.
- 4.STEP 1 extension: Weight regain and cardiometabolic effects after withdrawal of semaglutide: The STEP 1 trial extension
Wilding JPH, et al. · Diabetes, Obesity and Metabolism · 2022
Participants regained roughly two-thirds of their lost weight in the year after stopping semaglutide.
- 5.FDA clarifies policies for compounders as national GLP-1 supply begins to stabilize
U.S. Food and Drug Administration · 2025
Shortages resolved (tirzepatide December 2024, semaglutide February 2025) and the compounding enforcement deadlines that followed.
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