Key takeaways:
Wegovy (semaglutide) is an injectable medication for weight loss. Its active ingredient is semaglutide, which is made using recombinant DNA technology.
In addition to semaglutide, Wegovy’s inactive ingredients include disodium phosphate dihydrate (a buffer), sodium chloride (salt), and water. Wegovy does not contain a preservative since it comes in a single-use injection pen.
It’s possible to have an allergic reaction to one of Wegovy’s ingredients. Make sure your healthcare team has a full list of your allergies before starting Wegovy.
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Each ingredient found in a medication like Wegovy (semaglutide) has a specific role to play. The active ingredient, semaglutide, has the most important job since Wegovy won’t work without it.
Wegovy’s inactive ingredients are also necessary. They help keep Wegovy potent, transport its active ingredient, and more. So, what’s Wegovy made of, and how does it all come together?
What’s in Wegovy?
Wegovy contains a combination of active and inactive ingredients. The amount of each ingredient depends on the dose inside each injection pen.
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Active ingredient
Semaglutide is the active ingredient in Wegovy. It works by mimicking the effects of a gut hormone called glucagon-like peptide-1 (GLP-1), which is why it’s considered a GLP-1 receptor agonist.
Semaglutide is found in a few other medications, including Ozempic and Rybelsus.
The amount of semaglutide in each Wegovy pen can vary, depending on the dose:
0.25 mg (light-green pen)
0.5 mg (pink pen)
1 mg (brown pen)
1.7 mg (blue pen)
2.4 mg (black pen)
Inactive ingredients
Wegovy also has a short list of inactive ingredients that each have a specific purpose. These include:
Disodium phosphate dihydrate (buffer agent)
Sodium chloride (salt for tonicity)
Water (injection vehicle)
Hydrochloric acid or sodium hydroxide (to adjust acidity)
The 0.25 mg, 0.5 mg, and 1 mg Wegovy pens contain 0.5 mL of liquid. The 1.7 mg and 2.4 mg pens contain 0.75 mL of liquid.
Good to know: Compounded semaglutide may contain different or additional ingredients compared to FDA-approved Wegovy.
Does Wegovy contain preservatives?
No. Wegovy does not contain preservatives.
Since Wegovy comes in a single-use injection pen, it doesn’t need a preservative. That’s because it’s only used once before it is thrown away. Multidose pens, such as Ozempic and Saxenda (liraglutide), are used more than once, so they contain a preservative.
Can any ingredients in Wegovy cause an allergic reaction?
Yes. It’s possible to have an allergic reaction, including anaphylaxis, to an ingredient in Wegovy. And if you’ve had a reaction to a different GLP-1 receptor agonist before, it’s unknown if you would have the same reaction to Wegovy.
How they compare: Wegovy and Ozempic both contain semaglutide, but they aren’t exactly the same. Here’s how they compare.
The science behind Wegovy: Learn how Wegovy works to affect your appetite and food cravings to help you lose weight.
How to save: Glucagon-like peptide-1 (GLP-1) medications like Wegovy don’t need to break the bank. Explore ways to save on your prescription with this GLP-1 savings guide.
It’s a good idea to make your healthcare team aware of your allergies before starting a new medication. That way, potential issues can be identified and avoided before they happen.
But if you start experiencing symptoms of an allergic reaction after injecting Wegovy, call 911 or have someone take you to the ER. Examples of these symptoms include hives, difficulty breathing, and swelling of the face, lips, or tongue.
How is Wegovy made?
The semaglutide contained in Wegovy is considered a peptide. The FDA defines peptides as chains of 40 or fewer amino acids (protein building blocks). Some peptides are made using chemicals. Others, such as semaglutide, are made using recombinant DNA technology.
The recombinant DNA technology used to make semaglutide involves encoding DNA with instructions to make the peptide and then introducing the DNA into yeast cells to make peptide copies. The peptides are extracted, modified, and purified.
Semaglutide is made to look very similar to the GLP-1 found inside your body, but with a few changes to make it last longer.
The bottom line
Wegovy (semaglutide) is an injectable medication that contains an active ingredient called semaglutide. It also contains disodium phosphate dihydrate (buffer), sodium chloride (salt), and water. Each Wegovy pen is for one-time use only, so it doesn’t contain a preservative.
It’s possible to have an allergic reaction to one of Wegovy’s ingredients. Make sure your healthcare team knows about any allergies you have before starting Wegovy. Get emergency medical attention if you develop symptoms of an allergic reaction, such as difficulty breathing or swelling of the face, lips, or throat.
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References
Center for Drug Evaluation and Research. (2023). Clinical pharmacology considerations for peptide drug products: Guidance for industry. U.S. Food and Drug Administration.
European Medicines Agency. (n.d.). Annex I: Summary of product characteristics.
National Human Genome Research Institute. (2025). Recombinant DNA technology.
Novo Nordisk. (2024). Saxenda- liraglutide injection, solution [package insert]. DailyMed.
Novo Nordisk. (2024). Wegovy- semaglutide injection, solution [package insert]. DailyMed.
Szajek, A., et al. (2015). USP and synthetic therapeutic peptides. Quality Matters.
Usach, I., et al. (2019). Subcutaneous injection of drugs: Literature review of factors influencing pain sensation at the injection site. Advances in Therapy.
