Wegovy side effects: what the Canadian product monograph says

Most common side effects

In weight management clinical trials in adults, gastrointestinal disorders were reported in 73% of patients on Wegovy and in 47% of patients on placebo. Most episodes were mild or moderate, were of short duration and did not lead to discontinuation of Wegovy.

In adults on Wegovy, the median duration of nausea was 8 days, vomiting 2 days, diarrhea 3 days and constipation 47 days.

In clinical trials in adolescent patients, the most frequent reactions with Wegovy were nausea (42.1%), vomiting (36.1%), diarrhea (21.8%), headache (16.5%) and abdominal pain (15.0%).

The product monograph lists the reactions that occurred in 10% or more of adults on Wegovy in clinical trials. In this list, the first number is for Wegovy and the second number is for placebo.

• Nausea: 44% and 16%.
• Diarrhea: 30% and 16%.
• Vomiting: 24% and 6.3%.
• Constipation: 24% and 11%.
• Abdominal pain: 20% and 10%.
• Headache: 16% and 11%.
• Fatigue: 11% and 5.1%.

Frequency words in the patient information

The patient information of the product monograph groups the side effects by frequency. It says that the very common side effects usually go away over time.

• Very common (may affect more than 1 in 10 people): nausea or vomiting, diarrhea, constipation, stomach pain, feeling weak or tired, headache.
• Common (may affect up to 1 in 10 people): feeling dizzy, upset stomach or indigestion, burping, gas, bloating of the stomach, gastritis, reflux or heartburn.
• Also common: hair loss, injection site reactions, low blood sugar in patients with diabetes, low blood pressure.
• Also common: increase of pancreatic enzymes (such as lipase) shown in blood tests, hemorrhoids, a change in the way food or drink tastes.
• Uncommon (may affect up to 1 in 100 people): fast heartbeat, increase of pancreatic enzymes (such as amylase) shown in blood tests.
• Also uncommon: feeling faint or fainting/passing out, low blood sugar in patients without diabetes.
• Unknown: bowel obstruction, ileus, a delay in the emptying of the stomach, change in skin sensation.

Serious warnings and precautions box

The product monograph has a serious warnings and precautions box. It is about thyroid C-cell tumours.

In rodents, semaglutide causes thyroid C-cell tumours at clinically relevant exposures. The tumours depend on the dose and on the duration of treatment. It is unknown whether Wegovy causes thyroid C-cell tumours, including medullary thyroid carcinoma (MTC), in humans.

The patient information gives the symptoms to report. Tell your healthcare professional if you get a lump or swelling in your neck, hoarseness, trouble swallowing or shortness of breath. These may be symptoms of thyroid cancer.

The product monograph also lists these serious adverse reactions:

• Acute pancreatitis.
• Acute gallbladder disease.
• Retinal disorders, including diabetic retinopathy, in patients with type 2 diabetes.
• Hypoglycemia.
• Acute kidney injury.
• Hypersensitivity reactions.

Who must not use Wegovy

Wegovy is contraindicated in patients who are hypersensitive to this drug, to any ingredient in the formulation or to a component of the container.

Wegovy is contraindicated in patients with a personal or family history of medullary thyroid carcinoma (MTC). It is also contraindicated in patients with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).

Wegovy should not be used during pregnancy or breastfeeding. The product monograph says to discontinue semaglutide at least 2 months before a planned pregnancy.

The product monograph also says:

• Do not use Wegovy in patients with a history of suicidal attempts or active suicidal ideation.
• Wegovy is not recommended if you have severe gastroparesis (slow stomach emptying).
• Wegovy is not recommended for use in patients with end-stage renal disease.
• Wegovy is not recommended in patients with New York Heart Association (NYHA) Class IV heart failure.
• Wegovy is not indicated for use in pediatric patients below 12 years of age.
• Wegovy is not indicated for the treatment of type 1 diabetes mellitus or diabetic ketoacidosis.
• Wegovy should not be used in combination with any other medicine that contains semaglutide, or with any other GLP-1 receptor agonist.

When to stop and get medical help

The patient information has a table of serious side effects.

For two side effects in patients with type 2 diabetes, the table says to talk to your healthcare professional in all cases. These are diabetic retinopathy complications and severe hypoglycemia (low blood sugar).

If you notice a sudden loss of vision or rapidly worsening eyesight, urgently contact your doctor. If you have severe and on-going pain in the stomach area, see a healthcare professional straight away.

The product monograph tells health professionals to discontinue Wegovy in patients who experience suicidal thoughts or behaviours. It also says to discontinue Wegovy if a patient has a sustained increase in resting heart rate. If a hypersensitivity reaction occurs, the patient should discontinue Wegovy and promptly seek medical advice.

For these side effects, the table says to stop taking the drug and get immediate medical help:

• Gallstones (common): sudden pain in the upper stomach or back, often on the right, nausea, vomiting, indigestion, or cramping.
• Pancreatitis (uncommon): severe and ongoing pain in the stomach area.
• Appendicitis (uncommon): sudden pain in the middle or lower right side of the abdomen, chills, fever, nausea, vomiting.
• Acute kidney injury (uncommon): swelling in the legs, ankles and feet, feeling tired, confusion, shortness of breath, not enough urine.
• Severe allergic reaction, anaphylactic reaction or angioedema (rare): breathing problems, swelling of face, lips, tongue and/or throat with difficulty swallowing, and a fast heartbeat.
• Non-arteritic anterior ischemic optic neuropathy (very rare): sudden vision loss, blurring or cloudiness of vision, headaches.

Ask a health professional

This page repeats what the Canadian product monograph says. It is not medical advice. Ask your pharmacist or your prescriber what applies to you.