Semaglutide (Wegovy)
Is It Right for You?
A complete guide to Semaglutide (Wegovy) — what it treats, how it works, dosages, side effects, and when a clinician may prescribe it following an online consultation.
What Is Semaglutide (Wegovy)?
Wegovy is a brand of semaglutide — a glucagon-like peptide-1 (GLP-1) receptor agonist — licensed specifically for chronic weight management in adults with obesity or overweight with at least one weight-related comorbidity. It is administered as a once-weekly subcutaneous injection at doses of up to 2.4 mg — significantly higher than the doses used in semaglutide formulations for type 2 diabetes (Ozempic, 0.5–1 mg).
Semaglutide is the most clinically significant advance in pharmaceutical weight management in decades. In landmark clinical trials (STEP programme), Wegovy produced average weight reductions of approximately 15% of body weight over 68 weeks — far exceeding the efficacy of any previously approved weight-loss medication. This has been transformative for patients who have not achieved adequate weight loss through lifestyle intervention alone.
Wegovy is delivered via a pre-filled, single-use auto-injector pen, administered once weekly. It is prescribed as an adjunct to a reduced-calorie diet and increased physical activity — not as a standalone treatment. Long-term adherence is required, as weight tends to return after discontinuation.
Wegovy is a prescription-only medication in the UK and must be prescribed only by clinicians experienced in obesity management, following confirmation of eligibility criteria — which can now be done through a telehealth consultation.
What Conditions Is Wegovy Used For?
Wegovy is licensed for:
BMI ≥ 30 kg/m², as an adjunct to a reduced-calorie diet and increased physical activity.
BMI ≥ 27 kg/m² with at least one weight-related comorbidity such as type 2 diabetes, hypertension, dyslipidaemia, cardiovascular disease, or obstructive sleep apnoea.
recent evidence (SELECT trial) demonstrates that semaglutide 2.4 mg significantly reduces the risk of major cardiovascular events (heart attack, stroke, cardiovascular death) in adults with established cardiovascular disease who are overweight or obese — even in those without diabetes.
Obesity is a chronic condition requiring long-term management. The weight loss achieved with Wegovy is generally only maintained while treatment continues — most patients regain weight after discontinuation. Wegovy should be considered a long-term or indefinite treatment rather than a short course, in combination with sustained lifestyle changes.
How Does Wegovy Work?
Semaglutide is a synthetic analogue of GLP-1 — a hormone released from intestinal L cells in response to food intake. Naturally occurring GLP-1 has a very short half-life of approximately 2 minutes; semaglutide is engineered with a fatty acid chain that binds to albumin in the bloodstream, extending its half-life to approximately 7 days, allowing once-weekly dosing.
Semaglutide exerts its weight-reducing effects through multiple complementary mechanisms:
Appetite Suppression — Semaglutide activates GLP-1 receptors in the hypothalamus — the brain's principal appetite-regulating centre — reducing hunger signals and increasing satiety. Patients consistently report a dramatic reduction in appetite, reduced food cravings, and a diminished enjoyment of high-calorie foods.
Delayed Gastric Emptying — Semaglutide slows the rate at which the stomach empties after meals, prolonging the feeling of fullness after eating and reducing overall caloric intake.
Glucose-Dependent Insulin Secretion — At high doses, semaglutide stimulates insulin release in response to elevated blood glucose and suppresses glucagon secretion, improving glucose metabolism. This contributes to metabolic benefits in patients with type 2 diabetes or pre-diabetes.
Central Reward Pathway Modulation — Emerging evidence suggests semaglutide reduces the rewarding properties of food — particularly ultra-processed, high-fat, high-sugar foods — through action on mesolimbic pathways, contributing to reduced hedonic eating.
Dosages & Administration
The correct dose depends on the type and severity of infection, age, weight, and kidney function. Always follow your clinician's instructions. The table below is for general reference only.
Administration Tips
Inject once weekly on the same day each week, at any time of day, with or without food.
Inject subcutaneously into the abdomen, upper thigh, or upper arm — rotating injection sites each week to prevent lipodystrophy (fatty tissue changes at the injection site).
Do not inject into muscle — pinch the skin to ensure subcutaneous placement.
Wegovy pens are pre-filled, single-use, and disposable — they do not require priming or manual dose setting. Click the button until a click is heard and hold the pen in place for 10 seconds.
Store unused pens in the refrigerator (2–8°C). A single pen can be kept at room temperature (below 30°C) for up to 28 days.
If a weekly dose is missed, take it within 5 days. If more than 5 days have passed, skip it and resume on your next scheduled day. Do not take two doses in one week.
Side Effects of Wegovy
Gastrointestinal side effects are the most common and are directly related to GLP-1 receptor agonism and delayed gastric emptying. They are most prominent during dose escalation and typically improve over several weeks.
- Nausea (very common; most prominent in the first weeks of each dose increase)
- Vomiting
- Diarrhoea
- Constipation
- Abdominal pain and discomfort
- Belching and reflux
- Fatigue (particularly at initiation)
- Injection site reactions (redness, bruising)
- Headache
- Dizziness
- Acute pancreatitis — severe upper abdominal pain radiating to the back, nausea, vomiting; discontinue immediately and seek emergency care if suspected
- Gallbladder disease — gallstones and cholecystitis; risk increased with rapid weight loss from any cause
- Diabetic retinopathy complications — worsening of pre-existing retinopathy in patients with type 2 diabetes; ophthalmological assessment recommended before starting in diabetic patients with established retinopathy
- Acute kidney injury — related to dehydration from severe GI side effects; maintain adequate hydration
- Tachycardia (elevated resting heart rate) — semaglutide can increase resting heart rate by 10–20 bpm; monitor in patients with cardiac conditions
- Suicidal ideation and self-harm — rare reports; monitor mental health during treatment
In rodent studies, GLP-1 receptor agonists including semaglutide caused dose- and duration-dependent thyroid C-cell tumours. The relevance to humans is uncertain, but Wegovy is contraindicated in patients with a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN2). Report any unexplained neck lump, difficulty swallowing, or persistent hoarseness to your clinician.
Drug Interactions
Always disclose all medications to your clinician and pharmacist.
Due to delayed gastric emptying, there is a theoretical risk of reduced contraceptive efficacy. Use additional barrier contraception and discuss with your clinician.
Semaglutide slows gastric emptying, which may reduce and delay the absorption of co-administered oral drugs. Clinically significant interactions are uncommon at approved doses, but timing-sensitive oral medications (particularly oral contraceptives) should be taken consistently and not immediately before a Wegovy dose.
Wegovy's glucose-lowering effects combined with insulin or sulfonylureas increases hypoglycaemia risk. Dose adjustments of antidiabetic medications are often required when starting Wegovy.
Possible modest effects on warfarin exposure due to delayed absorption; INR monitoring is prudent when initiating Wegovy in anticoagulated patients.
Important Warnings
Acute pancreatitis has been reported with semaglutide. Discontinue immediately and seek emergency medical care if you develop severe, persistent abdominal pain, particularly pain radiating to the back, accompanied by nausea and vomiting. Do not restart semaglutide after a confirmed episode of pancreatitis.
Wegovy is contraindicated in patients with personal or family history of medullary thyroid carcinoma or MEN2. Report any neck lump, difficulty swallowing, hoarseness, or persistent throat discomfort to your clinician.
Stopping Wegovy typically results in gradual regain of most of the lost weight within 12 months. This reflects the chronic nature of obesity as a condition, not treatment failure. Long-term or indefinite treatment may be required for sustained weight management.
Wegovy is contraindicated during pregnancy. Animal studies have shown adverse fetal effects. Women of reproductive potential should use effective contraception during treatment and for at least 2 months after stopping. If pregnancy is confirmed, discontinue Wegovy immediately.
Speak to a Clinician About Treatment
Getting advice no longer means sitting in a waiting room. Through The GP Service, you can consult with a licensed clinician in minutes — from home, on your lunch break, or wherever works for you. If treatment is clinically appropriate, your clinician can issue a prescription during the consultation. A consultation does not guarantee a prescription.
The treatment you need, when you need it.
Wegovy FAQs
In the STEP clinical trials, patients taking semaglutide 2.4 mg once weekly lost an average of approximately 15% of their body weight over 68 weeks. However, individual results vary considerably — some patients lose significantly more (over 20%), while others achieve less. Weight loss requires consistent adherence to Wegovy alongside a reduced-calorie diet and increased physical activity.
Yes — clinical evidence from the STEP 4 extension trial showed that most patients regain the majority of lost weight within 12 months of stopping Wegovy. Obesity is a chronic condition, and Wegovy addresses its biological drivers. Stopping the medication removes that therapeutic effect. This is similar to stopping any long-term treatment for a chronic condition such as hypertension or diabetes.
Nausea is the most common side effect and is usually worst in the first few weeks of each dose increase. Practical strategies include: eating smaller, more frequent meals; avoiding high-fat, greasy, or very sweet foods; eating slowly; not lying down immediately after eating; staying well hydrated with small, frequent sips; and avoiding strong food smells that trigger nausea. Nausea typically diminishes significantly after 4 to 8 weeks at each dose level.
Yes. Semaglutide also has glucose-lowering effects and is highly effective in people with type 2 diabetes who are overweight or obese. However, if you have type 2 diabetes and are already on insulin or a sulfonylurea, your antidiabetic medications may need adjusting to prevent hypoglycaemia. Note that Ozempic (semaglutide at lower doses, 0.5–1 mg) is a separate product specifically licensed for type 2 diabetes — Wegovy is the formulation specifically licensed for weight management at 2.4 mg.
Yes. Wegovy pens are designed for self-injection and are straightforward to use. Each pen is pre-filled, single-use, and requires no priming. Your clinician or practice nurse will demonstrate the injection technique. Most patients find self-injection quick and virtually painless with the auto-injector design.