Key Points

• Wegovy (semaglutide) is a once-weekly weight loss medicine approved to help eligible people lose weight and keep it off.
• Common stomach side effects with Wegovy include mild to moderate nausea, diarrhea, vomiting, constipation, and abdominal pain. For most people, stomach side effects lessen or go away after a few weeks of treatment. Low blood sugar may also be common.
• More serious side effects with Wegovy are less common or rare, but include a risk for thyroid cancer, which has been seen in animal studies, inflammation of your pancreas (pancreatitis), gallstones, and low blood sugar (hypoglycemia).

What is Wegovy?

Wegovy (semaglutide) is a weight loss medicine approved to be used in adults and children 12 years and older with obesity, or excess weight and weight-related health problems (like high blood pressure or high cholesterol).

How is it given?

Wegovy comes as an injection that is given once-a-week as a subcutaneous (under the skin) injection (shot) in your abdomen, thigh or upper arm. You’ll use the shot on the same day of each week, with or without a meal. Your healthcare provider will teach you how to give the shot at home for added convenience.

For most people, the injection is not painful, as it is given with very fine needle.

How does it work for weight loss?

Wegovy works by acting like the natural hormone called incretin that targets areas of the brain involved in controlling your appetite and food intake. This can help you eat less, which can result in weight loss. Wegovy is recommended to be used with healthy eating and an exercise program to maximize its benefits.

Wegovy is classified as a glucagon-like peptide-1 (GLP-1) receptor agonist and is the same medicine found in Ozempic and Rybelsus used for type 2 diabetes. GLP-1 targets area of the brain that helps to regulate appetite, especially after eating. It also slows how quickly the stomach empties, which makes you feel fuller for longer. In addition to this, Wegovy enhances the production of insulin.

You may see some weight loss in the 4 weeks of treatment, but the full effects may not occur for several months. In clinical studies submitted to the FDA, weight loss continued over a 68-week period.

Wegovy treatment is recommended for long-term use if it’s effective for you. Because you will use it for a long period of time, it’s important to become familiar with possible side effects and how to recognize them.

6 side effects of Wegovy and how to manage them

Here, let’s look at 6 of the top side effects with Wegovy. Some are common and others are more serious or rare. Most common side effects are short-term and only last a few days or weeks. We’ll offer tips on how you can recognize and manage these side effects so you can stay on treatment and meet your weight loss goals.

1. Stomach problems

Stomach (abdominal) side effects with GLP-1 agonist agents like Wegovy are common and well-known, but are usually mild and clear up in a few weeks. The most common side effect with Wegovy is nausea and occurs in about 44% of people. Others include diarrhea (30%), vomiting (24%), constipation (24%), stomach-area pain (20%), feeling bloated (7%), heartburn (5%), belching or gas (6%).

Stomach side effects tend to occur at the beginning of treatment and when your dose is increased too quickly. Because of this, your healthcare provider will slowly increase your dose every 4 weeks over a 16 week period, until you reach your normal dose. You can take Wegovy with or without food. Stomach-related problems have been reported to occur in adults and adolescents.

The good news is that for most people these side effects are mild, temporary and will not interfere with long-term treatment. They typically subside with a few weeks of starting treatment.

In general, about 5% to 10% of people will need to stop treatment due to stomach side effects with GLP-1 agonists. In studies, the most common side effects that led to people stopping treatment were nausea, vomiting, and diarrhea.

Tips for managing stomach side effects

If you have stomach side effects like nausea when first starting treatment, you can help to manage it by:

• eating more slowly
• consuming smaller meals
• selecting more bland, low-fat foods (like crackers, toast and rice)
• avoiding greasy, fried foods
• eating foods that contain water (like soup or gelatin)
• not lying down after eating
• going outside for fresh air

If you experience stomach side effects with Wegovy that bother you, worsen or do not go away, call your healthcare provider for further evaluation.

2. Low blood sugar

Low blood sugar, also called hypoglycemia, can happen with Wegovy treatment in both adults and adolescents, but is not a frequent side effect. The chances for this side effect may be greater if you also take certain drugs for type 2 diabetes, including sulfonylureas (for example: glipizide, glimepiride or glyburide) or insulin. Wegovy works by slowing down your stomach emptying and may change how some medicines work in your body.

Low blood sugar is a serious, but infrequent side effect with Wegovy treatment. In studies, low blood sugar occurred in 6% of patients taking Wegovy and 2% taking a placebo (inactive treatment). Low blood sugar has also been reported in patients taking GLP-1 receptor agonists who do not have type 2 diabetes.

One of the advantages of using the GLP-1 receptor agonists in general is the low risk of hypoglycemia.

Tips for managing low blood sugar

Call your doctor right away if you have any of these signs or symptoms:

• dizziness, feeling lightheaded or jittery
• headache
• feeling tired, drowsiness
• anxiety, irritability or other mood changes
• blurred vision
• weakness or shakiness
• a fast heartbeat
• confusion
• slurred speech
• hunger
• sweating

Ask your doctor what you should do if you develop symptoms of low blood sugar. This may include taking glucose (sugar) tablets, a glucose liquid, or fruit juice. You and your doctor may need to more closely monitor your blood sugar during treatment with Wegovy.

Tell your healthcare provider if you are taking other medicines to treat diabetes, including sulfonylureas or insulin. Your doctor may need to change your dose of any type 2 diabetes medicines.

Do not exceed the dose of Wegovy prescribed by your healthcare provider, which may increase your risk for low blood sugar.

3. Allergic Reactions

Serious hypersensitivity (allergic) reactions have been reported with the use of semaglutide, the active ingredient in Wegovy. In some people, these reactions may be life-threatening.

In studies, adolescents 12 years and older had more reports of rash and itching (3%), when compared to adults treated with Wegovy.

Tips for managing allergic reactions

Stop taking this medicine and contact emergency medical services right away if you have any of these symptoms:

• swelling of your face, lips, mouth, tongue or throat
• trouble breathing, swallowing or talking
• severe rash, hives or itching
• very rapid heartbeat
• wheezing or feeling of chest tightness
• fainting or feeling dizzy
• blistered or peeling skin (with or without a fever)

Do not use Wegovy if you are allergic to it or have had an allergic reaction with any semaglutide product or its inactive ingredients. You can find a list of inactive ingredients in the package insert or ask your pharmacist.

4. Risk of thyroid tumors or thyroid cancer

Your thyroid is a small gland found in the front of your neck area. It helps to control many functions in your body by making and releasing certain hormones.

One of the the most serious but rare warnings with Wegovy includes a risk for thyroid tumors or thyroid cancer, which has been seen in rodent studies. It is not known if Wegovy will cause thyroid tumors or thyroid cancer in humans, but it carries a Boxed Warning for this possible side effect, the FDA’s most prominent warning.

You should not use Wegovy if you or anyone in your family have ever had a type of thyroid cancer called medullary thyroid carcinoma (MTC) or if you have an endocrine system condition called Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).

Cases of MTC have been seen in patients treated with another GLP-1 receptor agonist known as liraglutide (Saxenda, Victoza) after it was approved by the FDA. However, it is not known if liraglutide caused these tumors because there was not enough data in the reports to draw a final conclusion.

Your doctor will check your thyroid gland (found in your neck area) for nodules. A blood test (serum calcitonin) or a thyroid ultrasound (imaging test) may be used to monitor for thyroid disease, but this is not commonly done because the tests are not very specific. However, if your doctor suspects thyroid disease, they may order these tests and do further evaluations.

Tips for managing possible thyroid disease

If you notice any of the following signs or symptoms, contact your doctor right away:

• a lump or swelling in the neck
• neck pain
• a hoarse voice or voice changes
• trouble swallowing
• trouble breathing
• a cough that won’t go away

5. Acute pancreatitis

Your pancreas is an important organ that lies behind the lower part of your stomach. Your pancreas releases enzymes that aid digestion of food and makes hormones (insulin) that help manage your blood sugar (blood glucose). Acute pancreatitis is a sudden inflammation of your pancreas.

Acute pancreatitis was reported in studies with Wegovy. With other GLP-1 receptor agonists and other semaglutide products, some cases of acute pancreatitis have been fatal. According to the manufacturer, acute pancreatitis was reported in studies in 5 patients taking Wegovy vs. 1 patient on placebo (an inactive shot).

Tips for management of acute pancreatitis

Acute pancreatitis can be a severe or even deadly side effect, so call your doctor right away and stop taking Wegovy if you experience any of these signs or symptoms.

• severe stomach pain, that may radiate to your back
• severe pain in your back
• severe nausea (upset stomach)
• vomiting (throwing up)

If your doctor finds that you have developed acute pancreatitis, you will need to stop Wegovy treatment and not restart it.

Wegovy has not been studied in patients with a history of pancreatitis. If you’ve previously had pancreatitis, it is not known if you are more at risk for a recurrence with this treatment. It is not known if this medicine can be used safely in people with a history of pancreatitis.

6. Gallbladder problems

Your gallbladder is a small, pouch-like organ located just below your liver. It stores bile that is produced by the liver. Bile is released from the gallbladder into the small intestine and helps to digest fat from your diet.

Wegovy can cause problems with your gallbladder and the need for surgery, including gallstones (cholelithiasis) or gallbladder inflammation (cholecystitis). Sometimes rapid weight loss can cause gallbladder disease, but you don’t have to lose weight to have gallbladder problems, either.

While gallbladder disease is not as common as general stomach side effects with Wegovy, it can be much more serious. In Wegovy studies in adults, the occurrence of gallstones occurred in 1.6% of those who received Wegovy and 0.7% of those who received a placebo (an inactive shot). Gallbladder inflammation was even less common, and occurred in 0.6% of adults receiving Wegovy and 0.2% of placebo-treated patients.

Adolescents 12 years and older treated with Wegovy had higher rates of gallstones (3.8%) and gallbladder inflammation (0.8%) in studies when compared to adults. Adolescents who received the placebo did not have reports of gallbladder problems.

Tips for managing gallbladder disease

If you experience any of the following, contact your healthcare provider right away to be evaluated for possible gallbladder inflammation or gallstones:

• pain in the upper right area of your stomach
• pain in the right shoulder or between the shoulder blades
• yellowing of your skin or eyes (jaundice)
• a fever with chills
• dark-colored urine
• light-colored (clay-colored) stools

These are not all of the side effects that occur with Wegovy. Learn more here: Wegovy side effects (in more detail)

You can also review a more complete list of side effects in the manufacturer's Medication Guide. If you need a copy, you can get one from your pharmacist or doctor.

Bottom Line

• Wegovy (semaglutide) is a weight loss medicine approved to be used in adults and children 12 years and older with obesity, or excess weight and weight-related health problems (like high blood pressure or high cholesterol). It is given as a shot once per week.
• The most common side effects with Wegovy are stomach-related and include nausea, diarrhea, vomiting, constipation, and pain in the stomach area. For most people, stomach side effects lessen or go away after a few weeks of treatment.
• Low blood sugar (hypoglycemia) can also be a serious and common side effect, especially in people taking certain type 2 diabetes medicines.
• Other serious but less common or rare side effects with Wegovy include a risk for thyroid cancer or tumors, which has been seen in animal studies, inflammation of your pancreas (pancreatitis), gallbladder disease (like gallstones), and severe, possibly life-threatening allergies.

This is not all the information you need to know about Wegovy (semaglutide) for safe and effective use and does not take the place of your doctor’s directions. Review the full product information and discuss this information and any questions you have with your doctor or other health care provider.