What ingredients are in Wegovy?

Read any drug packaging and you’ll find the “active” ingredient — that’s what brings all the health benefits — as well as the “inactive” ones. What are those, exactly? Things like stabilizers, preservatives, or coatings that don’t treat your condition but help the medication be in its most stable, useful form. It's good to know all of the ingredients, both active and inactive, so you can know exactly what you’re putting in your body, especially if you have certain allergies or drug interactions — and it turns out that while the same active ingredient makes the Wegovy weekly injection and daily pill work, the inactive ingredients are different. What are they, and do any of them pose risks for allergic reactions or drug interactions? Read on for more info.

Wegovy is a brand name for the medication semaglutide that’s been approved by the FDA for weight loss, and it’s available in weekly injectable and daily oral pill versions. Like other types of medications, Wegovy has both active ingredients (that would be the semaglutide) as well as inactive ingredients, which are things like preservatives. 

The active ingredient is semaglutide. It mimics GLP-1, short for glucagon-like peptide 1, a hormone your body naturally produces when you eat. This hormone signals the pancreas to release insulin as a way to control blood sugar, and when this happens, it prompts feelings of fullness. 

The ingredient also slows the rate of stomach emptying, which boosts the effect of helping you feel full, according to Dr. Robert Kushner, M.D., professor of medicine and medical education at Northwestern University Feinberg School of Medicine in Chicago. 

According to Wegovy's manufacturer, Novo Nordisk, these are the inactive ingredients in Wegovy:

• Sodium chloride: This is another name for salt, which is used to increase the shelf life of medications.

• Disodium phosphate dihydrate: This one is also a type of salt, used as a buffer, a.k.a. an ingredient that keeps a solution stable. This helps keep Wegovy from changing significantly when other ingredients are added or when a solution's temperature changes. For instance, it's recommended that you store Wegovy in the refrigerator, but if needed, it can be kept at room temperature with the pen cap still on for up to 28 days, according to the manufacturer. A buffer ingredient like this is what allows that to happen.

• Water: This helps with the solution’s consistency, ensuring it can be delivered easily through an injection. 

• Hydrochloric acid or sodium hydroxide: These are used to adjust the acidity in the injection solution, which is another way to keep the semaglutide stable. Hydrochloric acid makes the solution more acidic while sodium hydroxide can make it less acidic.

Oral Wegovy pill active ingredient

Just like the injection, the active ingredient in the daily pill is semaglutide. Semaglutide mimics GLP-1, short for glucagon-like peptide 1, a hormone your body naturally produces when you eat. This hormone signals the pancreas to release insulin as a way to control blood sugar, and when this happens, it prompts feelings of fullness. 

 The ingredient also slows the rate of stomach emptying, which boosts the effect of helping you feel full. The different doses available for the tablets are: 1.5 mg, 4 mg, 9 mg, and 25 mg.

Oral Wegovy pill inactive ingredients

According to Wegovy's manufacturer, Novo Nordisk, these are the inactive ingredients in the Wegovy pill:

• Salcaprozate sodium (SNAC): This is an absorption enhancer in Wegovy tablets that helps the body absorb the active ingredient, semaglutide.

Magnesium stearate: This is a salt that’s often used to coat a medication such as a tablet; it’s common and non-hazardous, according to the National Institute of Health’s National Center for Biotechnology Information.

Some of the inactive ingredients in Wegovy like sodium chloride could be considered short-term preservatives, but the more standard preservatives such as benzyl alcohol are not needed in Wegovy since each injection pen is only used one time. Those preservatives are only needed for medications that are used more than once.

Although use of the word "preservatives" can sometimes prompt negative associations, keep in mind that one of the preservatives in Wegovy is simply salt, which has been used to stabilize and preserve foods and medications for centuries. And a buffer like disodium phosphate dihydrate is often used as an emulsifier, fermentation aid, and binder in foods like whipping cream and is considered safe for humans.

The semaglutide that's in Wegovy is produced using what's called recombinant DNA technology. This is a laboratory process that blends genetic material from different sources to create DNA sequences. For semaglutide, these sequences are encoded with directions to make a certain type of peptide (the building blocks of protein) that is similar to naturally-occurring GLP-1.

Any medication, including over-the-counter options like aspirin and cough syrup, comes with a risk of side effects. These can range from mild and temporary reactions to more serious health risks.

The most common side effects of GLP-1 medications like Wegovy are nausea, vomiting, diarrhea, and acid reflux (find the full list of side effects here). While allergic reactions can happen, they tend to be rare, says Vukasinov. For example, according to an estimate from the American Academy of Asthma Allergy & Immunology, less than 1% of patients report an allergic reaction to semaglutide.

An allergic effect seen with either semaglutide itself or with one of the inactive ingredients would involve the type of reactions seen with other types of serious allergies, he adds. These include:

• Sudden and widening rash or hives

• Itching anywhere in the body, but particularly around the injection site

• Swelling of the face, tongue, or throat

• Swelling in the skin around the injection site

• Severe dizziness

• Trouble breathing, such as difficulty taking a full breath, or as if something feels lodged in the throat

If you experience any of these, particularly if your symptoms are worsening, it's important to get medical attention immediately, Vukasinov says.

You can also experience a much more minor allergic reaction that doesn't require medical help, adds Kushner. This would be tied to a mild irritation at the injection site, he says, like a small amount of redness, tenderness, or discomfort. That reaction tends to diminish within hours of the injection, so talk with your doctor if those symptoms are lingering for over a few days.

"Some of the inactive ingredients in Wegovy may have an effect on how well you absorb other medications," says Dr. Paunel Vukasinov, M.D., an internal medicine doctor at Medical Offices of Manhattan in New York. "Because of that, you should do a medication review with your health team."

For example, disodium phosphate dihydrate may prevent calcium absorption, Vukasinov says, so it could interfere with a calcium supplement if you’re taking one for bone density. In addition, sodium chloride may interfere with medications related to kidney function, high blood pressure, or heart issues. Although the amount in Wegovy is minor, it’s still worth talking to your doctor if you’re on other medication, he says.

Wegovy, whether in injection or tablet form, contains both active and inactive ingredients. The active ingredient, semaglutide, helps reduce appetite and delay stomach emptying, which prolongs feelings of fullness. The inactive ingredients do important things like help absorption or keep the product stable. While it’s rare, some ingredients may cause an allergic reaction, so if you've just started taking Wegovy and you have hives, itching, swelling, dizziness, or trouble breathing, get medical attention immediately.