Semaglutide quick reference
What is Semaglutide?
Once-weekly GLP-1 drug sold as Ozempic and Wegovy.
People use it to cut appetite and lose weight.
Approved for diabetes, weight, heart risk and liver disease (MASH).
How Semaglutide works
Signals fullness in the brain and cuts hunger.
Food stays longer, so meals feel larger.
Raises insulin and lowers glucagon when sugar is high.
Albumin binding gives a half-life of about a week.
What Semaglutide is studied for
Lost 14.9% at 68 weeks vs 2.4% on placebo (STEP 1).
7.2 mg lost 18.8% vs 15.5% on 2.4 mg at 72 weeks.
20% fewer heart attacks, strokes or CV deaths (SELECT).
24% fewer kidney events in diabetes with kidney disease (FLOW).
Two-thirds of lost weight returned within a year (STEP 1 extension).
In rats it acted on appetite centres without lowering energy use.
Semaglutide dosing protocol
| Weeks | Weekly amount on the Wegovy label |
|---|---|
| 1–4 | 0.25 mg |
| 5–8 | 0.5 mg |
| 9–12 | 1 mg |
| 13–16 | 1.7 mg |
| 17+ | 2.4 mg maintenance (1.7 mg if 2.4 is not tolerated) |
| Optional | 7.2 mg (Wegovy HD) after at least 4 weeks at 2.4 mg |
Diabetes (Ozempic): 0.25 mg for 4 weeks, then 0.5 mg, with optional increases to 1 mg and 2 mg.
Label and trial amounts come from the sources below. Community amounts are what people report; they have not been tested.
Mixing
Brand pens come ready to use. Mixing a research vial is community practice only.
What the research found
Average body-weight change in the main obesity trials:
STEP 1: Wilding JP et al., N Engl J Med 2021 (NCT03548935). STEP UP (all randomized, 72 weeks, Wegovy label 06/2026): 7.2 mg −18.8%, 2.4 mg −15.5%, placebo −3.9%. Wegovy HD approved in the US March 19, 2026.
Semaglutide community experience
What users report. Not tested in trials.
Positive reports
- Less food interest Meals feel easier to shrink or skip.
- Smaller portions Many see fewer cravings within weeks.
- Lower doses can work Some do fine below the top dose with fewer side effects.
- Training helps Lifting plus protein goes with better strength.
Negative & mixed
- Nausea at step-ups Often lasts 1–2 weeks after each increase.
- Constipation and reflux Common, along with low energy and sulfur burps.
- Hair and face changes Fast loss can mean hair shedding and a gaunt face.
- Hard to eat protein Low appetite makes protein goals tough.
Semaglutide stacking
Main way to protect muscle while appetite is low.
Studied as CagriSema: 20.4% loss at 68 weeks.
Community muscle pairing. No trial shows it prevents lean loss.
Semaglutide side effects & safety
Common
- Nausea: 44% vs 16% on placebo (2.4 mg).
- Diarrhoea: 30% vs 16%.
- Vomiting: 24% vs 6%.
- Constipation: 24% vs 11%.
- Fatigue: 11% vs 5%.
- Mostly during step-ups.
Less common
- Dysesthesia (skin tingling or burning): 6% at 2.4 mg, 22% at 7.2 mg.
- Hair loss: 3% at 2.4 mg, 6% at 7.2 mg.
- Gallbladder problems, pancreatitis, dehydration-related kidney injury.
- Thyroid C-cell tumours in rodents; human risk unknown.
Precautions
- Avoid with personal or family history of medullary thyroid cancer or MEN2.
- Insulin or sulfonylureas raise low blood sugar risk.
- Stop when pregnancy is recognised; stop 2 months before a planned one.
- Tell your doctor before surgery; slower stomach emptying raises aspiration risk.
- Do not combine with other GLP-1 drugs.
Our verdict on Semaglutide
Longest track record, with heart and kidney benefits. Newer drugs lose more weight, but it works.
Semaglutide FAQ
How much weight loss should I expect?
STEP 1: 14.9% at 68 weeks on 2.4 mg vs 2.4% on placebo.
What happens if I stop?
STEP 1 extension: two-thirds of lost weight returned within a year.
Semaglutide or tirzepatide?
SURMOUNT-5: tirzepatide 20.2% vs semaglutide 13.7% at 72 weeks.
How long does it stay in the body?
Half-life is about 1 week. It lingers 5–7 weeks after the last dose.
Sources
- Wegovy and Ozempic US prescribing information
- Wilding JP et al. N Engl J Med 2021 (STEP 1, NCT03548935)
- FDA approval of Wegovy HD 7.2 mg, March 19, 2026
- Wegovy US prescribing information, revised 06/2026 (dosing, adverse reactions, SELECT, STEP UP)
- Wilding JP et al. Diabetes Obes Metab 2022;24:1553 (STEP 1 extension, stopping)
- Perkovic V et al. N Engl J Med 2024;391:109 (FLOW, kidney outcomes)
- Gabery S et al. JCI Insight 2020;5:e133429 (semaglutide in rodents, brain pathways)
- Aronne LJ et al. N Engl J Med 2025;393:26 (SURMOUNT-5, vs tirzepatide)
- Garvey WT et al. N Engl J Med 2025;393:635 (REDEFINE 1, CagriSema)