Wegovy Side Effects: How Common They Are, the 7.2 mg Dose and When to Get Help

Stomach and gut side effects are the most common with Wegovy, and they happen mostly while the dose is being increased. This guide sets out how often each side effect happened in the trials, as reported in the UK product information for the Wegovy injection, what changes at the higher 7.2 mg dose, which effects need urgent attention and how to report them.

Wegovy Side Effects at a Glance

Very common: headache, nausea, vomiting, diarrhoea, constipation, stomach pain and tiredness.

The Summary of Product Characteristics (SmPC) for the Wegovy injection groups side effects by how often they happened in clinical trials:

• Very common (more than 1 in 10 people): headache, feeling sick (nausea), vomiting, diarrhoea, constipation, stomach (abdominal) pain and tiredness.

• Common (up to 1 in 10 people): dizziness, changes in taste, unusual skin sensations, inflamed stomach lining (gastritis), acid reflux, indigestion, burping, wind, bloating, gallstones, hair loss and injection site reactions.

• Uncommon (up to 1 in 100 people): low blood pressure, including on standing up, faster heart rate, acute pancreatitis, slower stomach emptying, kidney stones, and low blood sugar in people without type 2 diabetes.

• Rare (up to 1 in 1,000 people): severe allergic reactions (anaphylaxis), swelling under the skin (angioedema) and hip fracture.

• Very rare (up to 1 in 10,000 people): non-arteritic anterior ischaemic optic neuropathy (NAION), a condition that affects the nerve of the eye.

Blockage of the bowel (intestinal obstruction) has been reported since the medicine came onto the market, with frequency not known. Low blood sugar and worsening diabetic eye disease are common in people with type 2 diabetes. Wegovy is also available as a daily tablet, which has its own product information.

Stomach and Gut Side Effects

On 2.4 mg: nausea 43.9%, diarrhoea 29.7%, vomiting 24.5%, constipation 24.2%; mostly mild to moderate.

Section 4.8 of the SmPC reports these figures from the trials of Wegovy 2.4 mg, over 68 weeks:

• Nausea: 43.9% of people, against 16.1% on placebo.

• Diarrhoea: 29.7%, against 15.9%.

• Vomiting: 24.5%, against 6.3%.

• Constipation: 24.2%, against 11.1%.

Most were mild to moderate and short-lived, and they were reported most often while the dose was being increased. Constipation tended to last longer. Stomach and gut side effects led 4.3% of people to stop treatment for good.

Vomiting and diarrhoea can cause dehydration, which in rare cases can affect the kidneys. The SmPC advises taking care to avoid losing too much fluid, so keep drinking and speak to your prescriber or a pharmacist if you cannot keep fluids down. People with gastroparesis may have more severe stomach side effects.

Side Effects at the 7.2 mg Dose

At 7.2 mg, stomach effects are similar, and unusual skin sensations affected 21.6% of people.

For some adults with obesity, the dose can go up to 7.2 mg. The SmPC reports the STEP UP trials at this dose, over 72 weeks:

• Nausea 38.9% (12.6% on placebo), diarrhoea 24.2% (11.6%), vomiting 22.1% (5.7%) and constipation 20.4% (7.6%), mostly during the first 20 weeks.

• Unusual skin sensations (dysaesthesia), such as tingling, burning or sensitive skin, were reported by 21.6% of people on 7.2 mg, against 0.3% on placebo. Most were mild to moderate and got better while people kept taking it.

• Hair loss was reported by 5.3% on 7.2 mg, against 1.0% on placebo.

Other Common Side Effects

Headache, tiredness, hair loss (2.5% on 2.4 mg), gallstones (1.6%) and a small rise in heart rate.

The figures below are from section 4.8 of the SmPC.

• Headache and tiredness are very common, mainly while the dose is increasing.

• Hair loss was reported by 2.5% of people on 2.4 mg and 1.0% on placebo. It was mainly mild, most people recovered while still taking it, and it was more frequent in people who lost more weight.

• Gallstones were reported by 1.6% of people on 2.4 mg, and led to an inflamed gallbladder in 0.6%.

• Heart rate: on average it rose by 3 beats per minute.

• Burping, indigestion, wind, bloating and reflux are all common.

Serious Side Effects: When to Get Help

Persistent, severe stomach pain, sudden loss of vision or a severe allergic reaction need urgent help.

Some side effects are uncommon or rare but need urgent attention:

• Acute pancreatitis was confirmed in 0.2% of people on 2.4 mg in the main trials. The SmPC says to seek immediate medical attention for persistent, severe stomach pain. If pancreatitis is confirmed, Wegovy should not be restarted.

• Sudden loss of vision, even partial, needs urgent assessment by an eye specialist. Studies in people with type 2 diabetes suggest semaglutide may be linked to about one extra case of NAION per 10,000 years of treatment.

• Severe allergic reactions, such as swelling of the face or throat or difficulty breathing, need emergency help.

• Low blood sugar is mainly a risk with insulin or a sulphonylurea; your prescriber may lower those doses.

• Diabetic eye disease: in people with pre-existing diabetic retinopathy, a rapid improvement in blood sugar has been linked to a temporary worsening, so they should be monitored closely.

If you think you are having a serious reaction, call 999 or go to A&E. For urgent advice that is not an emergency, call NHS 111.

Rarer Findings From the Heart Outcomes Trial

In SELECT, hip and pelvis fractures were more common on Wegovy in women and people aged 75 and over.

SELECT followed more than 17,000 adults with heart disease for around 3 years. The SmPC reports that:

• Hip and pelvis fractures were more common on Wegovy than placebo in women (1.0% against 0.2%) and in people aged 75 and over (2.4% against 0.6%).

• Kidney stones were reported by 1.2% on Wegovy and 0.8% on placebo.

• People who had had bariatric surgery had more serious low blood sugar episodes on Wegovy (2 of 87 people) than on placebo (0 of 97).

Pregnancy, Breastfeeding and Contraception

Use contraception; not in pregnancy or breastfeeding; stop at least 2 months before a planned pregnancy.

• Contraception: the SmPC recommends that women who could become pregnant use contraception while taking Wegovy.

• Pregnancy: Wegovy should not be used during pregnancy. If you want to become pregnant, stop it at least 2 months before, because it stays in the body for a long time. Any pregnancy while taking Wegovy can be reported to the Novo Nordisk pregnancy registry.

• Breastfeeding: the SmPC says Wegovy should not be used while breastfeeding.

Before an Operation or Procedure

Tell the team you take Wegovy, because it slows stomach emptying.

Wegovy slows down how quickly the stomach empties. The SmPC notes reports of food or fluid being breathed into the lungs (pulmonary aspiration) in people taking this type of medicine who had a general anaesthetic or deep sedation. If you are due to have an operation or procedure, tell the team that you take Wegovy.

Thyroid Questions

Thyroid C-cell tumours were seen in rodents; the SmPC says relevance for humans is considered low.

In 2-year studies in rats and mice, semaglutide caused thyroid C-cell tumours. The SmPC describes this as a class effect of GLP-1 medicines in rodents, caused by a mechanism to which rodents are particularly sensitive, and says the relevance for humans is considered low but cannot be completely excluded. Tell your prescriber about your medical history before starting.

Reporting Side Effects

Tell your prescriber and report suspected side effects to the MHRA Yellow Card scheme.

Tell your prescriber or pharmacist about any side effect that bothers you or does not go away. You can also report suspected side effects to the MHRA Yellow Card scheme, online or through the Yellow Card app.

Frequently Asked Questions