Wegovy Side Effects: What You Should Know

Common side effects of Wegovy are experienced by more than 1 in 10 people include:

Gastrointestinal Effects:

• Nausea (reported in up to 44–61% of patients)
• Vomiting (up to 24%)
• Diarrhoea (up to 30%)
• Constipation (up to 24%)
• Abdominal pain or discomfort (up to 20%)
• Indigestion (unclear)

Other common side effects:

• Headache (up to 15%)
• Fatigue (up to 11%)
• Dizziness (up to 8%)
• Hair loss (up to 4%)

• Within 24–72 hours of the first injection: Some people notice early symptoms such as nausea, reduced appetite, mild headache, fatigue, or a “full” feeling.
• Weeks 1–4 (starting dose): This is when most common side effects first appear, including nausea, constipation or diarrhoea, abdominal discomfort, headache, and dizziness.
• After each dose increase: Side effects often reappear or get worse in the first few days after a dose increase. They typically settle within 1–2 weeks.
• After 2–3 months: For most people, side effects significantly reduce or resolve as the body adapts.

First few days to 2 weeks

Most common side effects, such as nausea, vomiting, diarrhoea, constipation, bloating, headache, dizziness, and fatigue, usually:

• Begin shortly after starting treatment or increasing the dose
• Peak within the first few days
• Improve within 7–14 days

During dose increases (first 8–16 weeks)

Each time the dose is increased:

• Side effects may briefly return or worsen
• These usually settle again within 1–2 weeks
• This is why Wegovy is titrated slowly.

After 2–3 months on a stable dose

For most people:

• Side effects significantly reduce or disappear
• Ongoing symptoms are uncommon and usually linked to hydration, nutrition, or rapid weight loss, rather than the drug itself

Long-term or rare effects

Some effects can persist or appear later:

• Hair shedding: may last several weeks to a few months, usually temporary and related to weight loss rather than the medication
• Gallbladder issues: may occur months into treatment, particularly with rapid weight loss
• Pancreatitis: rare, but can occur at any time and requires immediate medical attention

Although uncommon, Wegovy can cause serious side effects that require prompt medical attention.

Serious side effects include:

Gallbladder disease (e.g. gallstones, cholecystitis)

Wegovy: ~1.5–2.0%
Placebo: ~0.7–1.0%

What this means:

• About 1-2 in 100 people
• Often linked to rapid weight loss rather than direct drug toxicity

Pancreatitis (inflammation of the pancreas)

• Wegovy: ~0.2–0.3%
• Placebo: Similar or not significantly different

What this means:

• Around 2-3 in 1,000 people will get pancreatitis with Wegovy
• Rare, but potentially serious and requires urgent medical attention
• High risk individuals include those who have a history of pancreatitis, uncontrolled type-2 diabetes, very high cholesterol levels and heavy drinkers

Severe hypoglycaemia (low blood sugar)

(Primarily in people with diabetes taking insulin or sulfonylureas)

• Wegovy: ~0.5-1%
• Non-diabetics: Very rare

What this means:

• Mostly a risk when combined with medication used to treat diabetes

Serious dehydration

(Usually secondary to severe vomiting or diarrhoea)

• Wegovy: <1%
• Exact figures vary, but classified as uncommon

What this means:

• Rare, but risk increases if fluid intake is poor or vomiting is persistent

Severe allergic reactions

• Wegovy: <0.1% (less than 1 in 1,000)

What this means:

• Extremely rare, but potentially life-threatening

Diabetic retinopathy (in people with diabetes)

• Wegovy: ~0.3–1%
• Risk higher in patients with pre-existing eye disease

What this means:

• Rare; mainly relevant for people with long-standing diabetes

While many side effects of Wegovy are mild and temporary, the following strategies can help you manage them effectively:

Start with a lower dose

Gradual dose escalation can reduce nausea, vomiting, and other gastrointestinal symptoms.

Following your prescriber’s recommended schedule, taking the medication at the same time each day, and allowing your body to adjust before increasing the dose can improve tolerability.

Eat smaller, more frequent meals

This helps minimise nausea and indigestion.

Choosing bland, low-fat foods and eating slowly can further reduce gastrointestinal discomfort.

Pairing meals with plenty of water and avoiding lying down immediately after eating can also help.

Avoid high-fat or very spicy foods

These can worsen gastrointestinal discomfort.

Opting for lighter, bland meals and incorporating easily digestible foods can help reduce nausea, bloating, and indigestion while taking Wegovy.

Stay hydrated

Drinking plenty of water can help manage constipation and fatigue.

Sipping fluids consistently throughout the day, rather than in large amounts at once, also supports digestion and helps the body adjust to Wegovy more comfortably.

Use fibre-rich foods or supplements

This supports regular bowel movements and reduces constipation.

Fruits, vegetables, whole grains, and, if needed, a gentle fibre supplement can help maintain healthy digestion while taking Wegovy.

Increase fibre gradually and continue drinking plenty of water to avoid worsening gastrointestinal discomfort.

Rest when needed

Short naps or lighter activity can help manage fatigue.

Listening to your body, pacing yourself throughout the day, and prioritising adequate sleep at night can improve energy levels and overall tolerance to Wegovy.

Report persistent or severe symptoms

Always speak with your healthcare provider if side effects do not improve, as adjustments may be necessary.

Wegovy is considered safe for long-term use, and most people do not experience serious ongoing side effects.

Common early symptoms such as nausea, bloating, constipation, or diarrhoea usually settle within weeks as the body adjusts.

Some long-term effects can occur, but they are uncommon.

Gallbladder problems, often linked to rapid weight loss rather than the medication itself, and very rare cases of pancreatitis have been reported. Whilst these conditions are serious, they are not permanent and usually resolve within 1-2 weeks with medical intervention.

Most side effects resolve within a couple of weeks.

If symptoms persist beyond 2–3 weeks, interfere with daily life, or you are unable to keep food or fluids down, you should contact your prescriber or pharmacy, as your dose may need adjusting.

You may also wish to discuss alternatives, such as Mounjaro.

Current clinical evidence does not show that Wegovy increases the risk of cancer in humans.

The main concern relates to thyroid C-cell tumours, which have been seen only in animal studies at very high doses. No cases have been confirmed in people taking semaglutide.

Because of these animal findings, Wegovy carries a precaution advising that it should not be used by anyone with a personal or family history of medullary thyroid carcinoma (MTC) or MEN2 (Multiple Endocrine Neoplasia type 2).

In the UK, Wegovy carries a “black triangle” (▼) symbol, which means it is under additional monitoring by the MHRA.

This doesn’t mean the medicine is unsafe, it simply indicates that it is new to the market, and regulators want healthcare professionals and patients to report any side effects to the yellow card scheme so safety data can be collected more quickly.

All new medicines receive this status for a period, and it helps ensure any rare or unexpected side effects are identified as early as possible.

You can drink alcohol while taking Wegovy, but it’s best to do so in moderation.

Alcohol can increase the likelihood of gastrointestinal side effects, which are already common when starting Wegovy.

Limiting alcohol, particularly high-sugar or high-fat drinks, can help you feel more comfortable and stay on track with your weight-loss goals.

If you notice worsening side effects after drinking, reduce your intake or avoid alcohol altogether.

Further reading: Wegovy and alcohol

• Most side effects are mild and temporary, especially nausea, constipation, diarrhoea, headaches, fatigue, and bloating.
• Symptoms are most noticeable in the first few weeks or after dose increases and usually settle as the body adapts.
• Serious side effects are uncommon, including gallbladder problems and pancreatitis.
• Long-term complications are rare when Wegovy is used as prescribed and properly monitored.
• Good hydration, adequate nutrition, and gradual dose increases help reduce side effects.
• For most patients, the health benefits of sustained weight loss outweigh the risks, when taken under medical supervision.