Wegovy

Wegovy is a prescription weight management medicine containing semaglutide 2.4mg, administered as a once-weekly subcutaneous injection. It belongs to the class of glucagon-like peptide-1 (GLP-1) receptor agonists and represents a significant advance in the pharmacological treatment of obesity. Wegovy is indicated for use in adults with a body mass index (BMI) of 30 kg/m2 or above (obesity), or a BMI of 27 kg/m2 or above (overweight) in the presence of at least one weight-related comorbidity such as type 2 diabetes, hypertension, dyslipidaemia, obstructive sleep apnoea, or cardiovascular disease. It should be used as part of a comprehensive programme that includes a reduced-calorie diet and increased physical activity.

GLP-1 Receptor Agonism and the Science of Weight Loss

GLP-1 is a hormone produced naturally in the gut after eating. It acts on the brain's hypothalamus to reduce appetite, increases feelings of fullness (satiety), slows gastric emptying, and modulates blood glucose levels. Semaglutide is a long-acting synthetic analogue of GLP-1 that shares approximately 94% structural homology with the human hormone. At the higher dose used in Wegovy (2.4mg, compared with the 0.5-1mg doses used for type 2 diabetes in Ozempic), semaglutide produces a pronounced reduction in appetite and food intake, resulting in clinically significant and sustained weight loss.

Clinical Evidence - STEP Trials

The STEP (Semaglutide Treatment Effect in People with obesity) trial programme demonstrated impressive weight loss outcomes with Wegovy. In the landmark STEP 1 trial, participants treated with semaglutide 2.4mg over 68 weeks achieved an average weight loss of 14.9% of body weight, compared with 2.4% in the placebo group. Approximately 68% of participants lost more than 5% of their body weight, and one third lost more than 20%. The SELECT cardiovascular outcomes trial additionally demonstrated a 20% reduction in major adverse cardiovascular events in overweight and obese individuals with established cardiovascular disease, marking Wegovy as the first weight-loss medicine to demonstrate cardiovascular benefit.

Place in Treatment

Wegovy is the first GLP-1 agonist specifically licensed for obesity management in the UK at the 2.4mg dose. It is available through NHS specialist weight management services and private prescriptions. Supply constraints have periodically limited availability, and patients should discuss realistic expectations and the need for long-term use with their prescriber.

Wegovy is injected subcutaneously (into the fatty tissue under the skin) once a week, on the same day each week if possible. It can be taken at any time of day, with or without food.

Injection Sites and Technique

The recommended injection sites are the abdomen (avoiding the area immediately around the navel), the front of the thigh, or the upper arm. The injection site should be rotated with each dose to avoid lipodystrophy (fat tissue changes). The Wegovy pen is pre-filled and pre-set to the correct dose; there is no need to draw up medication. The needle is very fine and injections are generally well tolerated. Patients should be trained in injection technique by a healthcare professional before self-administering.

Dose Escalation Schedule

Wegovy is initiated at a low dose and escalated gradually over 16 weeks to the full maintenance dose of 2.4mg per week, in order to minimise gastrointestinal side effects. The schedule is: 0.25mg for weeks 1 to 4; 0.5mg for weeks 5 to 8; 1.0mg for weeks 9 to 12; 1.7mg for weeks 13 to 16; then 2.4mg from week 17 onwards. If gastrointestinal side effects are intolerable during escalation, the current dose may be maintained for an additional four weeks before increasing further. If the 2.4mg maintenance dose cannot be tolerated, the 1.7mg dose may be used, though weight loss outcomes may be reduced.

Wegovy is available in five dose strengths (0.25mg, 0.5mg, 1mg, 1.7mg, and 2.4mg) in separate pre-filled injection pens. The maintenance dose is 2.4mg once weekly, reached after a 16-week titration schedule. Each pen delivers a single dose and is then discarded.

No dose adjustment is required in patients with renal or hepatic impairment, as semaglutide is not renally cleared to a clinically significant extent. Wegovy should not be used in patients with a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN2). It is not recommended in pregnancy or breastfeeding. Women of childbearing potential should use effective contraception during treatment and for two months after the last dose.

Common Side Effects

• Nausea (very common, especially during dose escalation)
• Vomiting
• Diarrhoea
• Constipation
• Abdominal pain or discomfort
• Headache
• Fatigue
• Injection site reactions (redness, bruising, pain)

Serious Side Effects

• Acute pancreatitis: severe, persistent abdominal pain radiating to the back - stop treatment and seek emergency care immediately
• Gallbladder disease (cholelithiasis, cholecystitis): rapid weight loss increases gallstone risk
• Hypoglycaemia (when used in combination with insulin or sulphonylureas)
• Medullary thyroid carcinoma (seen in animal studies; patients with risk factors must not use Wegovy)
• Diabetic retinopathy complications (in patients with pre-existing retinopathy)
• Tachycardia (elevated heart rate)

Wegovy is a powerful medicine for weight management and must be used under medical supervision as part of a structured programme. It is not a short-term solution and requires long-term commitment.

Gastrointestinal Effects and Dehydration

Nausea, vomiting, and diarrhoea are very common, particularly during the early weeks of treatment and at each dose increase. These effects usually improve over time as the body adjusts. However, persistent vomiting or diarrhoea can lead to dehydration and electrolyte disturbances, which can impair renal function. Patients should ensure adequate fluid intake during periods of gastrointestinal upset and contact their healthcare provider if symptoms are severe or prolonged. Patients taking Wegovy alongside insulin or sulphonylureas are at increased risk of hypoglycaemia; blood glucose should be monitored closely and diabetes medication doses may need to be reduced.

Pancreatitis, Thyroid Tumours, and Long-Term Use

GLP-1 receptor agonists have been associated with an increased risk of pancreatitis in some studies. Patients with a history of pancreatitis should not use Wegovy. In animal studies, semaglutide caused dose-dependent thyroid C-cell tumours; while this has not been confirmed in humans, Wegovy is contraindicated in patients with a personal or family history of medullary thyroid carcinoma or MEN2. Long-term weight maintenance after stopping Wegovy typically requires continuation of lifestyle changes, and many patients regain weight when the medicine is discontinued. The decision to stop or continue treatment should be reviewed at least annually with a healthcare professional.

• Personal or family history of medullary thyroid carcinoma (MTC)
• Multiple Endocrine Neoplasia syndrome type 2 (MEN2)
• Known hypersensitivity to semaglutide or any excipient
• History of pancreatitis (relative contraindication)
• Pregnancy or breastfeeding
• Type 1 diabetes mellitus (not indicated)
• Diabetic ketoacidosis
• Severe gastroparesis or other severe gastrointestinal disease
• Children and adolescents under 18 years of age