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Side effects of Wegovy

Applies to both the Wegovy injection and the Wegovy pill: both contain semaglutide.

  • Gastrointestinal complaints are the most common and are usually mild
  • They mainly occur at the start and after a dose increase, and then subside
  • Serious side effects are rare, but recognizable
When to call your doctor?
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Nicolette Lammers
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The information on this page has been medically reviewed by

How often do Wegovy side effects occur?

The leaflet states how often each side effect occurs. Very common means in more than 1 in 10 users. Common means in 1 to 10 in 100 users. Sometimes means in 1 to 10 in 1,000 users.

In the STEP studies (68 weeks), participants received Wegovy or a placebo, a substance without active ingredients. Complaints also occurred in the placebo group. This shows what is truly caused by Wegovy:

Side effectWith WegovyWith placebo
Nausea44%16%
Diarrhea30%16%
Vomiting25%6%
Constipation24%11%
Abdominal pain20%10%

Approximately 4% of participants discontinued due to gastrointestinal complaints.

Side effects in the first weeks and per dose

With Wegovy, the dose is gradually increased, usually every four weeks. Symptoms primarily occur in the first weeks and may return or temporarily increase after each escalation. Subsequently, they decrease for most people as the body adapts to the new dose.

If the symptoms are too severe, your doctor may postpone an increase or temporarily keep the dose lower. The complete titration schedule can be found on the Wegovy page.

How long do Wegovy side effects last?

In the studies, most gastrointestinal complaints lasted only a short time. Nausea lasted an average of 8 days, diarrhea 3 days, and vomiting 2 days. Constipation lasted significantly longer, averaging 47 days, and therefore deserves extra attention.

For most people, the body adapts to the medication, and symptoms lessen after the titration phase. If they persist or worsen, consult your doctor.

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Common side effects and what you can do about them

For each complaint, you can read how often it occurs, what helps, and when to contact your doctor.

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Common side effects

  • Nausea Occurs in about 4 out of 10, especially during the titration phase. Helps: small portions, eating slowly, and low fat.

  • Diarrhea, vomiting, and dehydration Common and usually short-lived. Drink small sips of water throughout the day.

  • Constipation Occurs in about 1 out of 4 and can last longer. Helps: adequate hydration, fiber, and daily exercise.

  • Heartburn, belching, and bloating Due to slower stomach emptying. Helps: smaller meals, not eating late, and less carbonated drinks.

For persistent symptoms, your doctor can advise.

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Other symptoms you might notice

  • Fatigue and dizziness Especially at the beginning, also due to eating less. Eat small meals regularly and drink enough fluids.

  • Hair loss In 2.5% (placebo 1.0%). Usually associated with rapid weight loss and is generally temporary.

  • Itching or redness at the injection site Occurs at the injection site. Change the injection site every week.

  • Increased heart rate In studies, an average of 3 beats per minute higher.

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If in doubt, discuss it with your doctor

Rare but serious side effects

Serious side effects are uncommon. However, it is good to recognize the signs so that you can seek help in time.

Pancreatitis

Sign: severe, persistent abdominal pain, sometimes radiating to the back, with or without vomiting. Stop Wegovy and contact a doctor immediately.

Gallstones and gallbladder inflammation

Sign: pain in the upper right abdomen, fever, or a yellow discoloration of the skin or eyes. Contact your doctor immediately.

Severe allergic reaction

Sign: swelling of the face, lips, tongue, or throat, or difficulty breathing. Call 911.

Low blood sugar

If you also use insulin or certain other diabetes medications, your blood sugar may become too low. Signs include sweating, trembling, confusion, and heart palpitations. Your doctor can adjust the dosage of your other medication.

Eye side effects

In people with type 2 diabetes, an existing diabetes-related eye condition (diabetic retinopathy) may worsen. In addition, NAION, a very rare optic nerve disorder, has recently been included as a side effect in the product information. If you suddenly notice a worsening of your vision, contact a doctor immediately. You can read more in our blog about Ozempic and blindness.

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When to contact your doctor?

Call 911 if you experience swelling of the face, lips, tongue, or throat, or difficulty breathing or swallowing. Contact your doctor immediately for:

  • Persistent, severe abdominal pain
  • Prolonged vomiting or diarrhea
  • Yellow discoloration of the skin or eyes
  • Sudden worsening of vision
Outside office hours: Emergencies

Side effects of the Wegovy pill and Wegovy injection

The Wegovy pill and the Wegovy injection contain the same active ingredient, semaglutide. As a result, they cause similar side effects, especially nausea and diarrhea, and with the pill, symptoms also mainly occur during the titration phase.

The difference lies in the administration. You take the pill daily on an empty stomach, with a maximum of 120 ml of water, after which you do not eat or drink anything for 30 minutes. You administer the injection once a week. Does the tablet form also cause nausea? Yes, it can, in the same way as the injection. You can read more about the injection form on our page about weight loss with injections.

Pregnancy, contraception, and surgeries

Wegovy should not be used during pregnancy or while breastfeeding. If you plan to become pregnant, stop at least two months in advance, as semaglutide remains in the body for a long time. Use effective contraception during treatment.

Do you need to undergo surgery or an examination with general anesthesia or sedation? Always report that you are using Wegovy. Because your stomach empties more slowly, there is a risk that stomach contents may enter your lungs.

Is Wegovy dangerous in the long term?

Wegovy has been studied in trials lasting several years. The side effects observed in these studies are listed on this page. What happens after even longer use is not yet fully known. Therefore, the medication is under additional monitoring: new reports of side effects are followed with extra diligence.

If you stop Wegovy, side effects usually disappear. However, weight may return. This is not a side effect but something to discuss with your doctor beforehand.

Wegovy and alcohol

Alcohol can worsen gastrointestinal complaints such as nausea and, when using diabetes medication, increase the risk of low blood sugar. Therefore, be cautious, especially during the titration phase. You can read all about this topic in our blog about semaglutide and alcohol.

Does Wegovy have more or fewer side effects than Mounjaro or Ozempic?

Wegovy, Ozempic, and Mounjaro cause similar side effects, especially gastrointestinal complaints during the titration phase. Wegovy and Ozempic contain the same active ingredient, Mounjaro a different one. Your doctor will discuss which medication is right for you. You can read a detailed comparison in our blog about the difference between Mounjaro, Wegovy, Ozempic, and Saxenda.

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Reporting side effects and guidance

If you experience side effects, always discuss them with your doctor. You can also report side effects yourself to the Netherlands Pharmacovigilance Centre Lareb. At The Body Clinic, the doctor remains involved throughout the entire process. Symptoms are discussed during check-ups, and where necessary, the doctor adjusts the regimen or advises supportive medication for the stomach or bowel movements.

If you have questions about your own symptoms, please contact your treating physician.

Frequently asked questions about side effects 

Do you have a question about your own symptoms? Please contact your treating physician.

  • Most side effects are mild to moderate and temporary. Serious side effects are rare, but it is important to recognize the signs. A doctor will assess in advance whether Wegovy is suitable for your situation.

  • In multi-year studies, no side effects other than those listed on this page were observed. What happens after even longer use is being further monitored. The drug is therefore subject to additional monitoring.

  • Some people experience fatigue, especially at the beginning, partly due to reduced food intake. Regularly eating small meals and staying hydrated can help. If fatigue persists, please discuss it with your doctor.

  • No, both the pill and the injection contain the same active ingredient and cause similar side effects, especially nausea and diarrhea. The main difference lies in the method of administration.

  • Eat smaller portions, eat slowly, and stop as soon as you feel full. Be careful with fatty foods and drink enough water throughout the day. If the nausea remains severe, contact your doctor.

  • Most gastrointestinal complaints are short-lived. In studies, nausea lasted an average of 8 days and diarrhea 3 days. Constipation lasted longer, averaging 47 days.

  • For most people, the complaints diminish as the body gets used to the medication. They may temporarily return after a dose increase. If they persist, consult your doctor.

  • Symptoms often return or temporarily increase after a dose increase. Therefore, the dose is built up gradually. Your doctor may postpone an increase if the symptoms are too severe.