How Wegovy can cause side effects
Semaglutide activates GLP‑1 receptors. This helps reduce appetite and slow stomach emptying, which supports weight loss. The same mechanism commonly causes gastrointestinal symptoms (nausea, vomiting, constipation or diarrhoea), especially while your dose is increasing. Most side effects are dose‑dependent and improve as your body adapts.
If you’re experiencing troublesome symptoms during titration, speak with your prescriber about adjusting the pace or using short‑term supportive treatments.
Common Wegovy side effects
These reactions are frequently reported, particularly in the first weeks or after a dose increase:
- Nausea, vomiting or reduced appetite
- Diarrhoea or constipation; abdominal pain or cramping
- Indigestion, reflux/heartburn, bloating, gas or belching
- Headache, dizziness, fatigue
- Injection‑site redness or tenderness
- Fast resting heart rate (usually mild)
- Temporary hair shedding associated with rapid weight loss
Contact your prescriber if common effects are persistent, severe, or affecting hydration and nutrition.
Ways to reduce Wegovy side effects
- Follow the prescribed titration schedule. Slower increases can improve tolerability.
- Eat smaller, low‑fat meals. Avoid greasy, very spicy or very sweet foods.
- Sip fluids between meals to maintain hydration. Consider oral rehydration if at risk of dehydration.
- Prioritise protein and fibre. Add gentle activity and a consistent meal routine.
- Avoid alcohol while symptoms are active.
- Ask your clinician about short‑term supports (anti‑nausea options, stool softeners, fibre supplements).
- People with diabetes: monitor glucose closely if also on insulin or sulfonylureas—dose adjustments may be needed.
Serious risks: red‑flag symptoms
Stop Wegovy and seek urgent medical attention if you notice:
- Severe stomach pain, with or without vomiting, that won’t go away (possible pancreatitis)
- Right‑upper abdominal pain, fever, vomiting, yellowing of the skin/eyes (possible gallbladder disease)
- Very low urine output, swelling in legs/feet, or severe dehydration (possible kidney injury)
- Black or bloody stools, coughing/vomiting blood, or severe persistent abdominal pain
- Sudden vision changes, especially if you have diabetes or existing retinopathy
- Allergic reaction: rash, swelling of face/tongue/throat, trouble breathing, fainting
- Severe or worsening constipation with vomiting and abdominal distension (possible bowel obstruction/ileus)
- New or worsening low mood, depression or suicidal thoughts—seek prompt evaluation
In an emergency in Australia call 000. For poisoning concerns call the Poisons Information Centre on 13 11 26.
Who should avoid Wegovy or use extra caution
- Personal or family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2 (MEN2): do not use Wegovy
- Past pancreatitis, gallbladder disease, or severe gastrointestinal disease (e.g., gastroparesis): discuss risks first
- Significant kidney disease or dehydration risk
- Diabetic retinopathy: rapid glucose improvements can transiently worsen eye symptoms—monitor closely
- Pregnancy and breastfeeding: not recommended. Stop at least 2 months before a planned pregnancy
- Taking insulin or sulfonylureas: increased risk of hypoglycaemia—doses may need adjusting
Medicine and supplement interactions
- Insulin or sulfonylureas: higher risk of low blood sugar. Prescribers often reduce doses and increase monitoring.
- Other GLP‑1s or weight‑loss medicines: avoid duplication or unsafe combinations unless specifically advised.
- Delayed gastric emptying can affect absorption of some oral medicines. Discuss narrow‑therapeutic‑index drugs with your pharmacist.
- Alcohol may worsen nausea, vomiting or pancreatitis risk—avoid if symptomatic.
When side effects happen and how long they last
- First 1–4 weeks: nausea, early satiety and GI symptoms are most likely as dosing starts.
- During dose increases: symptoms may return briefly after each step up, then often settle.
- Months 2–3: constipation can appear or persist; addressing fibre, fluids and activity helps.
- Rapid weight‑loss phases: some report temporary hair shedding; it usually improves as weight stabilises and nutrition is optimised.
If symptoms don’t improve, speak to your clinician about slower titration, dose reduction, or alternative options.
When to see a GP vs go to emergency
See your GP or prescriber
- Persistent nausea, vomiting, constipation or diarrhoea
- Reflux/heartburn not settling with lifestyle changes
- Headache, dizziness or fatigue that interferes with daily life
- Questions about interactions, dose changes or nutrition support
Go to emergency (call 000)
- Severe or escalating abdominal pain with or without vomiting
- Signs of gallbladder disease, jaundice, or GI bleeding
- Signs of allergic reaction or severe dehydration
- Sudden vision changes
Frequently asked questions
What are the most common Wegovy side effects?
Nausea, vomiting, diarrhoea, constipation, abdominal pain, reflux/heartburn, bloating and gas are most common, especially during dose increases. Headache, dizziness, fatigue and injection‑site reactions can also occur.
How long do Wegovy side effects last?
Many settle after your body adapts—often within days to weeks after dose changes. If symptoms are persistent, severe or worsening, speak with your prescriber about slowing titration or using supportive treatments.
Does Wegovy cause hypoglycaemia?
On its own, Wegovy is less likely to cause low blood sugar. Risk increases if you use insulin or sulfonylureas. Your clinician may adjust doses and ask you to monitor glucose more closely.
Can I drink alcohol on Wegovy?
Alcohol can worsen nausea and vomiting and may increase pancreatitis risk. Avoid alcohol if you are experiencing GI symptoms or have a history of pancreatitis.
Does Wegovy cause hair loss?
Some people notice temporary hair shedding during rapid weight loss (telogen effluvium). It’s typically related to weight change and nutrition rather than a direct drug effect. Review protein intake and iron/B‑vitamins with your clinician.
What should I eat to reduce nausea on Wegovy?
Small, low‑fat meals; bland options (e.g., crackers, rice, bananas); ginger or peppermint tea; fluids between meals. Avoid greasy, highly spicy or very sweet foods and large portions.
Who should not take Wegovy?
Do not use if you have a personal or family history of medullary thyroid carcinoma or MEN2. Use caution and seek medical advice if you have past pancreatitis, gallbladder disease, severe GI disease, kidney disease, or are pregnant/breastfeeding.
Is this the same as Ozempic side effects?
Wegovy and Ozempic both contain semaglutide but are indicated and dosed differently. Side‑effect profiles overlap. See our dedicated pages for specific guidance.
Need help with Wegovy side effects?
Send a brief description of what you’re experiencing. A clinician will reply with next‑step guidance. If this is an emergency, call 000.
Response times are typically within one business day.
Key takeaways
- GI symptoms are the most common Wegovy side effects and often improve with time and slower titration.
- Know urgent red flags: severe abdominal pain, jaundice, dehydration, allergic reactions, vision changes.
- If side effects are limiting, talk to your clinician—dose adjustments and supportive care can help.