Semaglutide
Metabolic & weight lossAlso known as: Ozempic, Wegovy, Rybelsus, GLP-1 receptor agonist
A GLP-1 receptor agonist approved for type 2 diabetes and weight loss, sold as Ozempic, Wegovy, and Rybelsus.
2.What it is / mechanism
Semaglutide copies , a gut hormone released after eating. It lowers appetite, slows how fast the stomach empties, and helps the pancreas release insulin when blood sugar is high. The result is less hunger and steadier blood sugar. It is approved by the FDA for type 2 diabetes (Ozempic) and for weight loss (Wegovy), with a daily tablet version as well (Rybelsus). A fatty acid chain lets it bind to albumin, which stretches its to about a week and allows once weekly dosing.s1, s4
3.What the evidence supports
- Strong human dataProduces large, lasting weight loss in people with obesity, around 15 percent of body weight over about a year at the 2.4 mg dose.s1
From the STEP trials, large randomized studies of weekly semaglutide.
- Strong human dataLowers blood sugar in type 2 diabetes.s3
Its original approved use, backed by the SUSTAIN trials.
- Strong human dataCuts the risk of heart attack and stroke in people with heart disease and overweight or obesity.s2
The SELECT trial showed about a 20 percent drop in major cardiovascular events.
4.Dosing
| Route(s) | subcutaneous, once weekly (Ozempic, Wegovy), oral, once daily (Rybelsus) |
|---|---|
| Typical range | Injectable: start 0.25 mg weekly and step up every 4 weeks through 0.5, 1.0, and 1.7 mg to a target of up to 2.4 mg for weight loss. Diabetes doses usually top out around 1 to 2 mg. |
| Frequency | Once weekly by injection, or once daily as the oral tablet |
| Half-life | 7 days |
| Cycle guidance | Titrated up over about 16 weeks, then used continuously. |
| Notes | The slow exists to limit nausea. With a around 7 days, semaglutide builds up over the first month or so before it levels off, which is why each dose step is held for 4 weeks. See the plot below. Because it slows stomach emptying, it can change how fast other swallowed medicines are absorbed. |
Saturation plotter
Adjust the protocol to see how Semaglutide builds up in the blood over a cycle and whether it reaches a steady-state plateau.
Semaglutide: Blood level over time
Relative level (mg)Steady-state avg
1.4 mg
Peak / trough
2 / 1
Time to ~90% saturation
3.3 wk
Saturation at cycle end
100%
Teaching model that assumes even dose spacing, instant absorption, and single compartment clearance. An educational estimate, not a clinical PK simulation or dosing advice.
5.Reconstitution
| Vial sizes | 5 mg, 10 mg |
|---|---|
| Diluent | Bacteriostatic water for multi dose vials, or sterile water for single use |
| Concentration | Example: a 5 mg vial plus 2 mL of water gives 2.5 mg/mL, so a 1 mg dose is 0.4 mL, which is 40 units on a U-100 syringe. Research vials vary, so check your label. |
| Notes | The approved products come as prefilled pens or single dose vials with their own instructions. Research material is sold as lyophilized vials, commonly 5 mg or 10 mg. |
Reconstitution calculator
Pick your vial size and how much water you add to see the draw volume and syringe units for a dose. Open the full calculator →
Inputs
Reminder: 1 mg = 1,000 mcg
Total amount stated on the vial, e.g. 5 mg.
How much diluent you draw into the vial.
Target dose per injection, in mcg. 1 mg = 1,000 mcg.
Result
Draw to
40 units
= 0.4 mL on your syringe
- Concentration
- 2,500 mcg/mL
- Per unit
- 25 mcg / unit
- Doses per vial
- 5
Educational estimate only. Not medical or dosing advice. Verify every calculation independently before use.
6.Storage & stability
Lyophilized (dry)
| Temp | Freeze for long term storage, or 2 to 8 short term |
|---|---|
| Shelf life | Many months when frozen |
| Notes | Keep dry and out of light. If you have an approved product, follow its own storage instructions. |
Reconstituted
| Temp | 2 to 8 (refrigerated) |
|---|---|
| Shelf life | About 2 to 4 weeks |
| Notes | Do not freeze after mixing. Discard if cloudy or discolored. |
7.Reported side effects
- SeriousAcute pancreatitis(rare)s4Seek care for severe, lasting abdominal pain.
- WarningGallbladder problems, including gallstones(uncommon)s4Rapid weight loss can raise the risk of gallstones.
- CautionNausea(common)s3The most common effect, worst in the days after a dose increase, then it eases.
- CautionVomiting, diarrhea, or constipation(common)s3
- InfoReduced appetite(common)s3Expected, and part of how the drug works.
8.Interactions & stacking risks
Raises the risk of low blood sugar. These medicines may need to be lowered under medical supervision.
Semaglutide slows stomach emptying, which can change how quickly swallowed drugs are absorbed.
- WarningOther GLP-1 or incretin drugs (tirzepatide, retatrutide)
Do not combine drugs in this class. Using more than one at once stacks the gut effects and risks with no proven benefit.
9.Contraindications / who should avoid
- SeriousPersonal or family history of medullary thyroid cancer, or MEN2
Carries an FDA boxed warning based on thyroid C cell tumors seen in rodents. No clear human cases, but the warning stands.
- SeriousPregnancy or breastfeeding
Not for use in pregnancy. It is generally stopped well before trying to conceive.
- WarningHistory of pancreatitis
A possible pancreatitis signal means extra caution.
10.COA & purity notes
| Common adulterants | underdosed or mislabeled research vials, research semaglutide sold without the controls of the approved product, the wrong salt form sold as the active drug, giving less real drug than the label suggests |
|---|---|
| Mislabeling | There are FDA approved products made to pharmaceutical standards. Research or compounded vials are not held to the same controls, so a recent third party COA matters. Watch for a salt form listed at the same mg as the active drug, which means less real semaglutide. |
| Notes | Semaglutide has approved versions (Ozempic, Wegovy, Rybelsus). Research or compounded material is not the same product. |
11.Sources
- [s1]New England Journal of Medicine (2021). Once-weekly semaglutide for obesity (STEP program). rct
- [s2]Nature Medicine (2024). Long-term weight loss effects of semaglutide in obesity without diabetes in the SELECT trial. rct link
- [s3]New England Journal of Medicine (2016). Semaglutide and cardiovascular outcomes in patients with type 2 diabetes (SUSTAIN-6). rct link
- [s4]U.S. FDA / Drugs.com (2024). Semaglutide prescribing information and drug overview. regulatory link
Last reviewed 2026-07-07 · status: reviewed