01 How it works
Semaglutide mimics GLP-1, a gut hormone released after you eat. It tells the brain you are full, slows how fast the stomach empties, and helps the pancreas release insulin only when blood sugar is high. A fatty-acid tail keeps it in circulation for about a week, which is why it is taken once weekly.
02 Common uses
03 Run profile
It is started at a low dose and stepped up every four weeks, so the stomach has time to adjust. Most people reach their maintenance level after roughly four months. Taken once a week, on the same day.
The profile shows the shape. Ask for the numbers for your vial, your goal and your timeline.
04 Pairs well with
05 What to watch for
Stomach effects are the big one — nausea, diarrhoea, constipation, cramping — worst in the week or two after each step up. Eating smaller meals, easing off fatty food and staying hydrated help. Severe stomach pain that goes through to the back needs urgent attention (a rare risk of pancreatitis), as do gallbladder symptoms. Not for anyone with a personal or family history of medullary thyroid cancer or MEN2.
06 Evidence & status
Approved (as Ozempic®/Wegovy®)One of the best-studied compounds on this site. In large trials (STEP), people lost around 15% of body weight on average over about 16 months.
FDA-approved as the brand medicines Ozempic® (type 2 diabetes) and Wegovy® (weight management). This page covers the compound itself.
Sources
- WEGOVY- semaglutide injection, solution (prescribing information)DailyMed, U.S. National Library of Medicine, 2026 · Prescribing information
- OZEMPIC- semaglutide injection, solution (prescribing information)DailyMed, U.S. National Library of Medicine, 2026 · Prescribing information
- WEGOVY (semaglutide) injection, for subcutaneous use - initial FDA-approved labelU.S. Food and Drug Administration (Drugs@FDA), 2021 · Prescribing information
- Once-Weekly Semaglutide in Adults with Overweight or ObesityThe New England Journal of Medicine, 2021 · Clinical trial
- FDA declares end to semaglutide shortage, threatens makers of compounded versions of Ozempic, WegovySTAT (reporting the FDA decision of 21 February 2025), 2025 · Regulator document
- The Prohibited ListWorld Anti-Doping Agency, 2026 · Regulator document
Status and sources last checked November 3, 2026. Something out of date? Tell us.
07 How long until it works
Semaglutide builds slowly by design. The Wegovy schedule steps the dose up every four weeks, from 0.25mg to the 2.4mg maintenance dose over 16 weeks, so the stomach has time to adjust; the appetite effect is usually noticed in the first weeks, and weight loss follows the dose. In STEP 1, the main 68-week trial, people on 2.4mg had lost about 15% of their body weight by the end, with most of the loss in the first year and the curve flattening after that.
Averaged over the trial that is roughly 0.2% of body weight a week. Someone who holds at a lower dose because it is working, which the run profile above allows for, will lose more slowly, and that is fine.
08 Semaglutide vs tirzepatide
Both are once-weekly GLP-1 medicines; tirzepatide adds a second hormone pathway, GIP. In their main trials, average weight loss at the highest dose was about 15% for semaglutide (STEP 1, 68 weeks) and about 21% for tirzepatide (SURMOUNT-1, 72 weeks). Different trials, different people, but the gap is consistent.
Semaglutide is the one with the longer track record, the broader set of approved uses (its label now includes reducing heart-attack and stroke risk in adults with heart disease and obesity) and the most familiar side-effect picture. If results stall on semaglutide, tirzepatide is the usual next step, which is why the two are listed as a pair above.
Sema, Tirz or Reta, side by side →09 Stacking
Semaglutide is usually run on its own. Where people add something it is a recovery peptide (BPC-157) during training, or NAD+ for energy. No trial has tested semaglutide with any peptide, and the label’s only combination warning is the important one: with insulin or sulfonylureas, the risk of low blood sugar rises, so that needs a doctor’s input.
10 Where it stands legally
Semaglutide is FDA-approved as Ozempic (type 2 diabetes) and Wegovy (weight management, and cardiovascular risk reduction). Compounded semaglutide was permitted during the shortage; the FDA declared that shortage over on 21 February 2025, and shortage-based compounding had to end by 22 April 2025 for pharmacies and 22 May 2025 for outsourcing facilities.
It is not among the six peptides in the October 2026 HHS enforcement-discretion policy. In sport, it is not on WADA’s Prohibited List; from 2026 WADA monitors semaglutide use without banning it.
11 FAQ
How quickly does it work?
Appetite usually drops within the first week or two. Weight loss is gradual — most of the effect builds over months as the dose steps up.
Why start so low?
The starting dose is about tolerance, not results. Climbing slowly is what keeps nausea manageable.
What happens if I stop?
Appetite tends to return, and studies show much of the weight can come back without lifestyle changes in place.
What happens if I miss a semaglutide dose?
If your next dose is more than 2 days (48 hours) away, take the missed one as soon as you can. If it is less than 2 days away, skip it and take the next dose on the usual day. Never take two to catch up.
How long can a Wegovy pen stay out of the fridge?
Up to 28 days at room temperature, below 30°C (86°F), with the cap on. For a compounded vial, follow the pharmacy’s label.
Does semaglutide cause hair loss?
Hair loss was reported by about 3% of people on Wegovy in trials versus 1% on placebo. It is linked to rapid weight loss rather than the medicine itself and usually recovers as weight settles.
Can I change the day I take it?
Yes. The label allows the dose day to change as long as there are at least 2 days (48 hours) between doses.
Educational information only — not medical advice. The Daily Stack does not sell or supply any products. Talk to a licensed healthcare professional about your own health decisions.