Compounds / Semaglutide
Semaglutide
Ozempic · Wegovy · Rybelsus · compounded semaglutide
You probably know semaglutide as Ozempic (type 2 diabetes) or Wegovy (weight and heart risk), both once-weekly GLP-1 injections. Rybelsus, Ozempic tablets and Wegovy tablets are the once-a-day versions1–3. Compounded semaglutide from vials is not FDA approved, and FDA said the US shortage ended on February 21, 20257–8.
- Taken
- Once a week, injection (or daily tablet)
- Half-life
- About 1 week
- US status
- FDA-approved (Ozempic, Wegovy, Rybelsus)
- Type
- GLP-1 agonist
What is semaglutide and how does it work?
Semaglutide is a man-made version of GLP-1, a gut hormone that helps control appetite and how much you eat. It is 94% the same as human GLP-1 and works on the same receptor, including in the parts of the brain that regulate appetite2.
Semaglutide has a half-life of about 1 week, which is why the injection is taken once a week. It stays in the blood for about 5 to 7 weeks after the last Wegovy dose2. The tablets are taken every day.
What is semaglutide approved for?
Semaglutide is approved for type 2 diabetes as Ozempic and Rybelsus, and for weight management as Wegovy, in both the US and the UK1–3,6. Each brand also has heart, kidney or liver uses that differ between the two countries.
| Use | US | UK |
|---|---|---|
| Type 2 diabetes | Ozempic injection, Rybelsus and Ozempic tablets: adults | Ozempic: adults |
| Heart risk with type 2 diabetes | Ozempic: adults with heart disease. Rybelsus and Ozempic tablets: adults at high risk | Not a listed use for Ozempic |
| Kidney disease with type 2 diabetes | Ozempic: lowers the risk of kidney decline, kidney failure and heart death | Not a listed use for Ozempic |
| Weight management | Wegovy injection: adults with obesity, or overweight with a weight-related condition, and children 12 and older with obesity. Wegovy tablets: adults | Wegovy: adults with a BMI of 30 or more, or 27 to under 30 with a condition, and teens 12 and older with obesity who weigh more than 60 kg |
| Heart risk with overweight or obesity | Wegovy injection and tablets: adults with heart disease | Wegovy: adults with heart disease and a BMI of 27 or more |
| MASH liver disease with F2 to F3 scarring | Wegovy injection: adults (accelerated approval) | Wegovy: adults |
Sources: US labels section 1; UK SmPCs section 4.11–4,9. The UK also licenses Rybelsus tablets6. Compounded semaglutide isn't FDA-approved for any use7.
The labels say not to use Wegovy together with any other semaglutide product or any other GLP-1 medicine2.
What are the semaglutide doses?
Both injections start at 0.25 mg once a week for 4 weeks and go up every 4 weeks. Wegovy reaches its usual 2.4 mg dose in week 17. Ozempic can stay at 0.5 mg, or go up to 1 mg and then 2 mg if more blood sugar control is needed1–2.
| Weeks (earliest) | Wegovy | Ozempic |
|---|---|---|
| 1 to 4 | 0.25 mg (starting dose) | 0.25 mg (starting dose) |
| 5 to 8 | 0.5 mg | 0.5 mg (can stay here) |
| 9 to 12 | 1 mg | 1 mg, if more blood sugar control is needed |
| 13 to 16 | 1.7 mg | 2 mg, if more control is needed (maximum) |
| 17 onward | 2.4 mg (usual maintenance) | Stays on the dose reached |
Wegovy: if a step isn't tolerated, the label says to consider waiting 4 more weeks. US adults using Wegovy for weight can go to 7.2 mg after at least 4 weeks on 2.4 mg2.
The tablets step up every 30 days. Wegovy tablets go 1.5 mg, 4 mg and 9 mg, then 25 mg a day from day 912. Rybelsus goes 3 mg, then 7 mg, and 14 mg if needed. Ozempic tablets go 1.5 mg, then 4 mg, and 9 mg if needed3.
To turn a dose into units on an insulin syringe, the semaglutide dosage chart has each step at common vial strengths.
What are the side effects of semaglutide?
Nausea, diarrhea, vomiting and constipation are the most common side effects of semaglutide. In the Wegovy weight trials, 73% of people on 2.4 mg had a stomach or gut side effect, compared with 47% on placebo2.
| Side effect | Placebo | Wegovy 2.4 mg |
|---|---|---|
| Nausea | 16% | 44% |
| Diarrhea | 16% | 30% |
| Vomiting | 6% | 24% |
| Constipation | 11% | 24% |
| Stomach (abdominal) pain | 10% | 20% |
| Headache | 10% | 14% |
| Tiredness (fatigue) | 5% | 11% |
| Indigestion (dyspepsia) | 3% | 9% |
| Dizziness | 4% | 8% |
| Burping (eructation) | <1% | 7% |
| Hair loss | 1% | 3% |
6.8% stopped Wegovy because of side effects, vs 3.2% on placebo2. At diabetes doses, nausea was 15.8% on Ozempic 0.5 mg and 20.3% on 1 mg, vs 6.1% on placebo1.
The labels carry a boxed warning: semaglutide caused thyroid C-cell tumors in rodents, and it isn't known whether it does in people. It isn't used by anyone with a personal or family history of medullary thyroid cancer or with MEN 2. The other serious warnings are pancreatitis, gallbladder problems, low blood sugar in people with diabetes, kidney injury from dehydration, severe stomach problems, serious allergic reactions, eye problems in people with type 2 diabetes, a faster heart rate, and food entering the lungs under anesthesia2. The GLP-1 side effects guide covers when they start and how long they last.
How do you take semaglutide, and what if you miss a dose?
The injection goes under the skin of the belly, thigh or upper arm once a week, on the same day, at any time and with or without food1–2. Tablets are taken each morning on an empty stomach with up to 4 ounces of water, then nothing to eat, drink or take for at least 30 minutes2–3.
- Ozempic: take a missed dose within 5 days. After that, skip it1.
- Wegovy injection (US): take it if your next dose is more than 2 days away, otherwise skip it. After 2 or more missed doses in a row, the label says to restart the steps at a lower dose2. The UK SmPC uses a 5-day rule instead9.
- Tablets: skip the missed tablet and take the next one the following day2–3.
Before first use, keep pens in the fridge at 2°C to 8°C (36°F to 46°F) and never freeze them. Once in use, Ozempic and Wegovy FlexTouch pens last 56 days at 15°C to 30°C (59°F to 86°F) or in the fridge. Single-dose Wegovy pens can be kept at 8°C to 30°C for up to 28 days before the cap comes off1–2. The semaglutide tablets guide covers the daily versions in more detail.
How much weight do people lose on semaglutide?
In the main 68-week trial, adults without diabetes lost an average of 14.9% of their body weight on Wegovy 2.4 mg, compared with 2.4% on placebo. About 3 in 10 (30.2%) lost at least a fifth of their weight2.
| Trial | Who took part | On semaglutide | Comparison |
|---|---|---|---|
| STEP 1 (Wegovy Study 2), 68 weeks2 | Adults with obesity or overweight, no diabetes | −14.9% weight (2.4 mg) | −2.4% on placebo |
| Wegovy Study 3, 68 weeks2 | Adults with overweight or obesity and type 2 diabetes | −9.6% weight (2.4 mg) | −3.4% on placebo |
| Wegovy Study 8, 72 weeks2 | Adults with obesity | −18.8% weight (7.2 mg), −15.5% (2.4 mg) | −3.9% on placebo |
| Wegovy Study 7, 64 weeks2 | Adults with obesity or overweight | −13.6% weight (25 mg tablet) | −2.4% on placebo |
| SELECT (Wegovy Study 1)2 | 17,604 adults with heart disease and overweight or obesity, no diabetes | 6.5% had a heart attack, stroke or heart death | 8% on placebo |
| Ozempic monotherapy trial, 30 weeks1 | Adults with type 2 diabetes on diet and exercise only | HbA1c down 1.4 (0.5 mg) and 1.6 (1 mg) points | HbA1c down 0.1 on placebo |
In SELECT, the heart outcomes trial, Wegovy lowered the risk of a heart attack, stroke or heart death by 20% compared with placebo (hazard ratio 0.80)2. The Wegovy 7.2 mg guide covers the higher dose and its side effects.
How does semaglutide compare with tirzepatide?
In SURMOUNT-5, the one head-to-head trial, adults with obesity lost an average of 13.7% of their weight on semaglutide and 20.2% on tirzepatide after 72 weeks. The trial was open-label and funded by Eli Lilly, which makes tirzepatide10. Ozempic vs Mounjaro compares doses, side effects and uses.
Ozempic and Wegovy are the same medicine with different doses and approved uses1–2. The Ozempic vs Wegovy guide explains the differences.
Semaglutide fact sheet
- Type
- GLP-1 receptor agonist. Injected under the skin once a week, or taken as a tablet once a day.2
- Status (US)
- FDA approved as Ozempic injection and tablets and Rybelsus (type 2 diabetes)1,3, and Wegovy injection and tablets (weight reduction and heart risk; the injection also for MASH liver disease)2.
- Status (UK)
- Licensed as Ozempic, Wegovy and Rybelsus6. Since January 2026 the MHRA allows Wegovy up to 7.2 mg a week for adults with a BMI of 30 or more only5.
- Compounded vials (US)
- Not FDA approved and not reviewed by FDA before sale7. Grace periods for copies of the approved drug ended April 22, 2025 (pharmacies) and May 22, 2025 (outsourcing facilities)8.
- Doses on the label
- Ozempic: 0.25 mg → 0.5 mg, then 1 mg and 2 mg (max), weekly1. Wegovy: 0.25 mg up to 2.4 mg weekly over 16 weeks, max 7.2 mg (US adults, weight); tablets 1.5 mg up to 25 mg daily2.
Mixing math for Semaglutide
For a vial you mix yourself. Example numbers only: change them to match your own vial and dose. This does the math; it doesn't recommend a dose.
The mg printed on the vial label.
Bacteriostatic (bac) water, in mL.
Check whether it says mcg or mg. They differ by 1,000 times.
It's printed on the packet: 0.3, 0.5 or 1 mL.
5 mg vial + 2 mL water → 0.25 mg dose
Fill your syringe to
10units
The 10 line on a 1 mL syringe, which is 0.1 mL.
- Strength after mixing
- 2.5 mg/mL
- Each unit holds
- 25 mcg
- Doses in this vial
- 20
Show the math
- 5 mg × 1,000 = 5,000 mcg in the vial
- 5,000 mcg ÷ 2 mL = 2,500 mcg/mL
- 250 mcg ÷ 2,500 mcg/mL = 0.1 mL
- 0.1 mL × 100 units/mL = 10 units
Not what you expected? Check the numbers above, and confirm with your prescriber or pharmacist before you inject.
Semaglutide guides
- Semaglutide dosage chart: mg, mL and unitsPens give you a set dose in mg. If your semaglutide comes from a vial, each label dose also has to become mL and syringe units.
- Wegovy 7.2 mg: who it's for, how you step up, and what the trials showed7.2 mg is the highest Wegovy dose. You only get there after time on 2.4 mg, and the US and UK rules differ in a few places.
- Oral semaglutide: Rybelsus and Wegovy tablet doses and how to take themSemaglutide tablets only work well if you take them the label's way: empty stomach, a little water, then 30 minutes before anything else. The doses differ by brand and country.
Units for each dose: 0.25 mg · 0.5 mg · 1 mg · 1.7 mg · 2 mg · 2.4 mg
Also useful: Dose schedule planner · Missed dose checker · Units to dose
Questions
How many units is 0.25 mg of semaglutide?
In a 5 mg vial mixed with 2 mL of water (2.5 mg/mL), 0.25 mg is 10 units on a U-100 insulin syringe, or 0.1 mL. A vial of a different strength gives a different number. The dosage chart has the other common strengths.
Are Ozempic and Wegovy the same medicine?
Both contain semaglutide, made by Novo Nordisk. Ozempic is approved for type 2 diabetes and goes up to 2 mg a week. Wegovy is approved for weight reduction and heart risk and goes up to 2.4 mg a week, or 7.2 mg for some adults.
Is compounded semaglutide the same as Ozempic or Wegovy?
No. Compounded semaglutide is not FDA approved, and FDA doesn't check it before it's sold. FDA also says salt forms like semaglutide sodium or acetate are different active ingredients with no lawful basis for use in compounding.
How long does semaglutide stay in your body?
The half-life is about 1 week. The US labels say semaglutide is still in the blood for about 5 weeks after the last Ozempic dose, and about 5 to 7 weeks after the last Wegovy dose.
Is there a semaglutide pill?
Yes. In the US, Rybelsus and Ozempic tablets are approved for type 2 diabetes, and Wegovy tablets (up to 25 mg a day) for weight reduction and heart risk. They are taken once a day on an empty stomach.
Sources
- 1Ozempic (semaglutide) injection, US prescribing information (DailyMed). sections 1, 2.1, 2.2, 6.1, 12.3, 14 and 16.2; DailyMed version of June 2026
- 2Wegovy (semaglutide) injection and tablets, US prescribing information (DailyMed). sections 1, 2.1 to 2.4, 5, 6.1, 12.1, 12.3, 14 and 16; DailyMed version of June 2026
- 3Rybelsus and Ozempic (semaglutide) tablets, US prescribing information (DailyMed). sections 1, 2.1 and 2.2; revised 1/2026
- 4Ozempic 0.25 mg solution for injection in pre-filled pen, UK Summary of Product Characteristics (eMC). sections 4.1 and 6.3; text revised 07/2026
- 5MHRA: Medicines regulator approves up to 7.2mg dose of semaglutide (Wegovy) for patients with obesity only (GOV.UK). published January 16, 2026
- 6eMC: medicines containing semaglutide (UK product list). accessed November 8, 2026
- 7FDA: FDA's concerns with unapproved GLP-1 drugs used for weight loss. content current as of October 1, 2026
- 8FDA: FDA clarifies policies for compounders as national GLP-1 supply begins to stabilize. update of February 21, 2025; content current as of April 1, 2026
- 9Wegovy FlexTouch solution for injection in pre-filled pen, UK Summary of Product Characteristics (eMC). sections 4.1 and 4.2; accessed November 9, 2026
- 10Aronne LJ, et al. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity (SURMOUNT-5). N Engl J Med 2025;393:26-36. doi:10.1056/NEJMoa2416394; abstract
This page explains what labels and published studies say. It isn't medical advice and doesn't replace your prescriber or pharmacist.
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