This guide explains the common, mild, and serious side effects of Wegovy, Mounjaro, Ozempic, and Zepbound(GLP-1 medications).
Most side effects happen as your body adjusts to treatment and are usually temporary. However, some symptoms require urgent medical attention.
Use this guide when you need to:
Understand common side effects of GLP-1 medications
Know what counts as mild or moderate symptoms
Identify serious side effects that require urgent care
Check whether an injection site reaction is normal
What are the most common side effects of Wegovy, Mounjaro, Ozempic, Zepbound, or generic semaglutide?
The most common side effects of GLP-1 medications include:
Nausea
Vomiting
Diarrhoea
Constipation
Stomach discomfort or abdominal pain
Indigestion or heartburn
Bloating or gas
Fatigue
Other common side effects include:
Headache
Dizziness
Mild reactions at the injection site (pain, redness, swelling, or itching)
A faster than usual heart rate
A change in your sense of taste
Hair loss
These side effects are usually:
Mild to moderate
Temporary
More noticeable when starting treatment or increasing dose
Clinical trial data shows that fewer than 5% of patients stop treatment due to side effects.
Because generic semaglutide contains the same active ingredient as Wegovy and Ozempic, the side effect profile is the same as those of branded semaglutide.
What counts as mild or moderate side effects?
Mild or moderate side effects from Wegovy, Mounjaro, Ozempic, Zepbound, or generic semaglutide are symptoms that:
Do not prevent you from carrying out normal daily activities
Improve as your body adjusts to the medication
Can be managed with simple measures (for example, hydration or rest)
Examples of mild or moderate side effects include:
Mild nausea
Occasional headache
Temporary digestive discomfort
These symptoms are expected during treatment and do not usually require stopping the medication.
How can I avoid becoming dehydrated?
Nausea, vomiting, and diarrhoea from a GLP-1 medication can cause you to lose fluids. Severe dehydration can lead to kidney problems, including sudden kidney failure.
To help prevent dehydration:
Drink water steadily throughout the day, even if you do not feel thirsty
Increase your fluid intake if you are vomiting or have diarrhoea
Consider oral rehydration solutions if you have repeated vomiting or diarrhoea
Contact a healthcare professional or attend urgent care if you experience extreme thirst, very little urine, very dark urine, lightheadedness, confusion, or a rapid heartbeat.
Are there serious side effects I should watch for?
Yes. Some side effects from GLP-1 medications require immediate medical attention.
Stop using Wegovy, Mounjaro, Ozempic, Zepbound, or generic semaglutide and seek urgent care if you experience any of the following:
Signs of pancreatitis (inflammation of the pancreas)
Severe and persistent stomach pain, especially if the pain:
Is very intense (for example, 8 out of 10 or higher)
Prevents normal daily activities
Does not improve with rest or over-the-counter pain relief
Spreads to your back or under your right ribcage or shoulder
Severe vomiting, including:
Vomiting multiple times per day
Vomit containing blood
Vomit that looks like coffee grounds
Signs of a severe allergic reaction
Difficulty breathing
Swelling of the lips, tongue, or throat
A widespread rash or hives
These symptoms may indicate a life-threatening allergic reaction.
Signs of gallbladder problems
Severe pain under the right ribcage
Pain that spreads to the shoulder or back
Vomiting
Fever or high temperature
Yellowing of your skin or the whites of your eyes (jaundice)
Rapid heartbeat
Signs of severe dehydration or kidney problems
Extreme thirst or very dry mouth
Producing very little urine, or urine that is very dark
Severe lightheadedness, dizziness, or fainting
Confusion
Signs of a serious mental health change
New or worsening depression
Thoughts of suicide or thoughts of hurting yourself
Sudden or significant changes in mood or behaviour
Thyroid changes
A lump or swelling in your neck
Hoarseness
Trouble swallowing
Shortness of breath
What should I do if I experience serious side effects?
If you experience any of the symptoms listed above:
Call 911 immediately, or
Go to your nearest emergency department
If you are having thoughts of suicide or thoughts of hurting yourself, you can also contact the Canada Suicide Crisis Helpline on 9-8-8
MedExpress cannot provide emergency care, so urgent symptoms must be handled by emergency services.
I notice a lump at my injection site. Is this normal?
A small lump at the injection site can sometimes occur after using Wegovy, Mounjaro, Ozempic, Zepbound, or generic semaglutide.
This type of injection site reaction is usually:
Mild
Temporary
Not a cause for concern
However, you should contact a healthcare professional if the lump:
Persists for several days
Becomes larger or more painful
Shows signs of infection (for example, redness, warmth, or swelling)
Important: MedExpress clinical support and side effects
MedExpress provides ongoing clinical support through online messaging if you have questions about side effects or treatment.
MedExpress can help with:
Managing mild or moderate side effects
Deciding whether to continue treatment
Providing general clinical guidance
MedExpress cannot:
Diagnose emergencies
Treat severe reactions in real time
For urgent or severe symptoms, always use emergency medical services.
If you still need help after reviewing the information above, additional assistance is available.