Quick answer: Wegovy contains one active ingredient, semaglutide, plus a short list of inactive ingredients. The FDA label for Wegovy injection lists disodium phosphate dihydrate, sodium chloride, and water for injections, with the pH adjusted using sodium hydroxide and/or hydrochloric acid. Semaglutide is a synthetic version of a human gut hormone. Wegovy is a single-dose pen, so it does not contain an antimicrobial preservative. The inactive ingredients keep the solution stable and at the right pH. None of them cause weight loss on their own.
What is the main ingredient in Wegovy?
Semaglutide. It is a GLP-1 receptor agonist, a synthetic peptide modeled on human glucagon-like peptide-1, a hormone your gut releases after you eat. Native GLP-1 breaks down in minutes. Semaglutide is modified so it lasts about 7 days, which is why Wegovy is a once-weekly injection. It lowers appetite, slows how fast the stomach empties, and prompts insulin release. The weight loss comes mainly from eating less, not from speeding up metabolism.
What are the ingredients in Wegovy?
Per the FDA prescribing information, each 1 mL of Wegovy injection contains:
Active ingredient
- Semaglutide (supplied in pens delivering 0.25 mg, 0.5 mg, 1 mg, 1.7 mg, or 2.4 mg per dose)
Inactive ingredients
- Disodium phosphate dihydrate, 1.42 mg (pH buffer)
- Sodium chloride, 8.25 mg (tonicity agent)
- Water for injections (solvent)
- Sodium hydroxide and/or hydrochloric acid (added only to adjust pH)
That is the full list on the Wegovy injection label. Most of the volume is water. Wegovy does not contain a preservative because each pen is single-dose. This differs from Ozempic, a multi-dose semaglutide pen, which does contain the preservative phenol and propylene glycol.
What does each inactive ingredient do?
Disodium phosphate dihydrate is a buffer. It holds the solution at a stable pH so the semaglutide peptide does not clump or break down over the shelf life.
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Try the BMI Calculator →Sodium chloride is a tonicity agent. It brings the solution close to the salt concentration of body fluids, which makes the injection more comfortable and gentler on tissue.
Water for injections is sterile, purified pharmaceutical-grade water, not tap water. It is the base the other ingredients are mixed into.
Sodium hydroxide and hydrochloric acid are added in tiny amounts during manufacturing only to fine-tune the pH to the target. They are not active and are buffered in the final product.
Is Wegovy just semaglutide and water?
No. Water is most of the solution, but the buffer and the salt each do a specific job. Without the buffer the peptide would drift out of its stable pH range and degrade. The sodium chloride keeps the injection comfortable. These inactive ingredients are what let the medication stay stable and tolerable, even though Wegovy contains no preservative.
What are the ingredients in Ozempic compared to Wegovy?
Ozempic and Wegovy share the active-ingredient equivalence, semaglutide, made by the same manufacturer, but their inactive ingredients differ. Ozempic is a multi-dose pen, so it contains the preservative phenol plus propylene glycol. Wegovy is single-dose and contains neither. The doses and uses also differ: Wegovy goes up to 2.4 mg weekly for weight management, while Ozempic tops out at 2 mg weekly for type 2 diabetes.
Ingredient comparison table
| Ingredient | In Wegovy? | Role |
|---|---|---|
| Semaglutide | Yes | Active drug, GLP-1 receptor agonist |
| Disodium phosphate dihydrate | Yes | pH buffer |
| Sodium chloride | Yes | Tonicity agent |
| Water for injections | Yes | Sterile solvent |
| Sodium hydroxide / hydrochloric acid | Yes, trace | pH adjusters |
| Phenol (preservative) | No (in Ozempic) | Not used; Wegovy is single-dose |
| Propylene glycol | No (in Ozempic) | Not used in Wegovy |
What about compounded semaglutide ingredients?
Compounded semaglutide is prepared differently from brand Wegovy. It is often supplied as a freeze-dried powder that is mixed with a separate liquid before use, so the inactive ingredients differ from the pre-filled brand pen. Common components include the semaglutide active ingredient, a bulking agent, and a reconstitution liquid such as bacteriostatic water, which contains benzyl alcohol as a preservative. Because compounded products are made to a prescription rather than mass-produced under an approval, the exact formula varies by pharmacy. Note that after the FDA declared the semaglutide shortage resolved in early 2025, the period of enforcement discretion for compounding semaglutide ended that year, so availability of compounded versions changed. FormBlends works with licensed providers and compounding pharmacies; you can read more on our semaglutide page.
Does Wegovy contain allergens?
Wegovy does not contain common food allergens like gluten, dairy, or soy, and the pen contains no natural rubber latex, so people with latex allergy can use it. True allergic reactions to ingredients like phenol or propylene glycol are uncommon. Injection-site redness or itching is usually irritation rather than a true allergy. Hives, facial swelling, or trouble breathing are emergencies and need immediate care.
Why does Wegovy need refrigeration?
Semaglutide is a peptide and degrades faster when warm. Refrigeration keeps it stable through its shelf life. Once you start using a pen, it can stay at room temperature for up to 28 days. Do not freeze it. Freezing damages the peptide, and a frozen pen should be thrown away even after it thaws.
FAQ
What is Wegovy made of? One active ingredient, semaglutide, plus disodium phosphate dihydrate, sodium chloride, and water for injections, with pH adjusted by sodium hydroxide and/or hydrochloric acid.
What is the active ingredient in Wegovy? Semaglutide, a GLP-1 receptor agonist.
Are Wegovy and Ozempic ingredients the same? They share the active-ingredient equivalence, semaglutide. The maximum dose and approved use differ.
Does Wegovy contain phenol or propylene glycol? No. Those are in Ozempic, which is a multi-dose pen. Wegovy is single-dose and contains neither phenol nor propylene glycol.
Does Wegovy contain a preservative? No. Because each Wegovy pen is single-dose, it does not need an antimicrobial preservative.
Does Wegovy contain latex? No. The pen has no natural rubber latex.
Can I be allergic to Wegovy ingredients? Rarely. Most injection-site reactions are irritation. Severe systemic reactions are uncommon but need emergency care.
What is in compounded semaglutide? The semaglutide active ingredient plus different inactive ingredients than the brand pen, often a freeze-dried powder mixed with bacteriostatic water. The exact formula varies by pharmacy.
Sources
- Wegovy (semaglutide) FDA prescribing information, Novo Nordisk: https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/215256s000lbl.pdf
- electronic Medicines Compendium, Wegovy ingredient listing: https://www.medicines.org.uk/emc/product/13867/smpc
- STEP 1 trial (semaglutide weight management), NEJM 2021: https://www.nejm.org/doi/full/10.1056/NEJMoa2032183
- FDA, Medications Containing Semaglutide: https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/medications-containing-semaglutide-marketed-type-2-diabetes-or-weight-loss
- DailyMed, Wegovy label: https://dailymed.nlm.nih.gov/dailymed/
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