The active ingredient in Wegovy is semaglutide. This medication is known as human-glucagon-like-peptide-1 analogue, also known as a GLP-1 receptor agonist. Wegovy lowers body weight in humans mainly through reducing calorie intake. It regulates appetite by increasing feelings of fullness, while lowering feelings of hunger, leading to reduced food intake.

The active ingredient in Mounjaro is tirzepatide. This medication is known as a dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist. Mounjaro lowers body weight in humans mainly through reducing calorie intake. It regulates appetite by increasing feelings of fullness, delaying gastric emptying, and lowering feelings of hunger, leading to reduced food intake.

Wegovy (semaglutide) and Mounjaro (tirzepatide) are both licensed medications in the UK for the management of weight, alongside a reduced-calorie diet and increased physical activity.

Both medications can only be supplied or prescribed by a suitably qualified healthcare professional, such as a doctor, prescribing nurse, or pharmacist. They are not available over the counter.

During your consultation, your clinician will assess your medical history, current medications, and individual circumstances to determine whether Wegovy or Mounjaro is safe and appropriate for you.

You can read the relevant patient information leaflets for each medication for further details.

You can read the patient information leaflet here.

It can only be prescribed to adults (18yrs+) with at least one weight-related condition and a body mass index (BMI) of at least 27 kg/m2 or to people with a BMI of 30.0 kg/m2 or more. It is prescribed as part of a weight management programme that might include diet changes and exercise. You will be asked to confirm your BMI on booking, this will be confirmed, along with your measurements and blood pressure during your appointment. Wegovy is not suitable for patients that are pregnant or trying to conceive, or that are breast feeding.

Mounjaro can only be prescribed to adults (18 years and over) with at least one weight-related condition and a body mass index (BMI) of 27 kg/m² or higher, or to individuals with a BMI of 30.0 kg/m² or more.

It is prescribed as part of a comprehensive weight management programme, which may include dietary changes and increased physical activity.

You will be asked to confirm your BMI at the time of booking, which will be verified along with your measurements and blood pressure during your appointment.

Mounjaro is not suitable for patients who are pregnant, trying to conceive, or breastfeeding.

Both Wegovy (semaglutide) and Mounjaro (tirzepatide) are effective prescription medications for weight management when used alongside a reduced-calorie diet and increased physical activity. The amount of weight loss varies between individuals and depends on factors such as starting weight, adherence to treatment, diet, and lifestyle changes.

Wegovy works by mimicking the GLP-1 hormone, helping to reduce appetite, increase feelings of fullness, and lower overall calorie intake. Clinical trials have shown that many patients achieve clinically meaningful weight loss, with a significant proportion losing 5–15% or more of their body weight over time when combined with lifestyle changes.

Mounjaro works slightly differently, as it is a dual GIP and GLP-1 receptor agonist. This dual action can lead to enhanced appetite regulation and improved satiety. Clinical studies have shown that, on average, patients using Mounjaro may achieve greater weight loss than those using GLP-1 medicines alone, with some individuals losing 15–20% or more of their body weight.

While Mounjaro may lead to greater average weight loss in clinical trials, both treatments can be highly effective, and the most suitable option depends on your individual medical history, tolerability, and response to treatment. Your clinician will help determine whether Mounjaro or Wegovy is the safest and most appropriate option for you.

All patients should read the instructions for use included in the package leaflet carefully before administering this medicinal product. Our dedicated team will provide training on how to safely use the pen.

Wegovy is for subcutaneous use only (to be injected under the skin). It must not be given in a vein or in a muscle. Wegovy is administered once weekly at any time, independent of meals. It should be injected in the abdomen (preferred) or thigh, but can also be injected in the upper arms. The injection site and timing can be changed without dose adjustment. You can inject in the same body area each week, but make sure it is not in the same spot as used the last time.

You can also see information here also on how to use the pen and administer a dose safely here.

It is preferable that Wegovy is injected around the same time of the week, when the most convenient time has been chosen.

All patients should read the instructions for use included in the package leaflet carefully before administering this medicinal product. Our dedicated team will provide training on how to safely use the pen.

Mounjaro is for subcutaneous use only (to be injected under the skin). It must not be injected into a vein or muscle. Mounjaro is administered once weekly, at any time of day, with or without meals.

It should be injected into the abdomen (preferred) or thigh, and can also be injected into the upper arm. The injection site can be rotated, and the day or timing of injection can be changed if needed without dose adjustment. You may inject into the same general body area each week, but should avoid using the exact same spot consecutively.

You can also find further guidance on how to use the pen and administer a dose safely in the patient information leaflet.

It is preferable to inject Mounjaro on the same day each week, at a time that is most convenient for you.

Each Mounjaro pen contains 4 once-weekly doses. Therefore, each pen provides treatment for up to 28 days.

You will need to make an appointment to see the nurse to review your progress and obtain your next pen.

• 1 pen = 4 weeks treatment

• 2 pens = 8 weeks treatment

• 3 pens = 12 weeks treatment

Yes!

Your personalised plan is likely to include an increase in activity and some specific exercises. Exercise not only helps you manage weight, it has been shown to have a number of mental wellbeing and wider health benefits.

NHS Choices suggests adults should aim to:

• do strengthening activities that work all the major muscle groups (legs, hips, back, abdomen, chest, shoulders and arms) on at least 2 days a week
• do at least 150 minutes of moderate intensity activity a week or 75 minutes of vigorous intensity activity a week
• spread exercise evenly over 4 to 5 days a week, or every day
• reduce time spent sitting or lying down and break up long periods of not moving with some activity

The weight loss injection service is not suitable if any of the following apply:

• Patient is currently not registered with a GP
• Confirmed anaphylactic reaction to either:
  • A previous dose of semaglutide (Wegovy) or other GLP-1 agonist
  • Any of the components of the medication – refer to specific product information for list of excipients (www.medicines.org.uk) (e.g. propylene glycol)
• Informed consent has not been given for the supply or administration of the medication.
• Patients aged under 18 years or over 75 years of age.
• Current pregnancy or planned pregnancy within the next 2 months
• Breastfeeding
• History of / current eating disorder (includes bulimia and anorexia nervosa)
• Concomitant use of other GLP-1 agonists (see interactions below)
• Concomitant use of other weight loss medication (e.g. orlistat, Mysimba etc)
• Diabetes (Type 1 or Type 2)
• Pre-diabetes
• Patients with renal impairment
• History of pancreatitis
• Diabetic retinopathy (diabetics are wholly excluded)
• Heart failure
• Weight gain suspected to be caused by current medication

You should be in possession of a sharps bin if you are using Wegovy. Sharps bins are available at most pharmacy’s. Please use the sharps bin to dispose of used needles. If you require disposal of your sharps bin please see the following link.

We would recommend waiting until your sharps bin is nearly full or you are terminating treatment before requesting a collection from your local council, as you may not be entitled to have several collections in a year. Each council may have different provisions.

You should not use other weight loss medications at the same time as Wegovy. If you are currently using or finishing treatment with other weight loss medications ensure your clinician is aware if you did not mention this in your consultation before you start using Wegovy. They can advise any precautionary steps when switching over if needed.

Stopping Ozempic or Rybelsus and starting Wegovy: you should always start at the lowest dose of Wegovy: 0.25mg once weekly. Ensure at least a 7 day gap before finishing Ozempic/Rybelsus and starting Wegovy.

Stopping Saxenda (liraglutide) and starting Wegovy: you should start at the lowest dose of Wegovy: 0.25mg once weekly. Ensure a 7 day interval from the last dose of Saxenda to the first dose of Wegovy

Going forward if you wish to change from Wegovy to Saxenda you should advise your Saxenda prescriber about your current use of Wegovy. A 2 month interval after Wegovy is recommended before Saxenda use.

No minimal interval is currently required between starting Wegovy and stopping orlistat or Mysimba (naltrexone/bupropion) but they should NOT be used at the same time. Always inform your health care professional of current medications you are taking to ensure a safe and thorough consultation.

If you miss a dose you should administer as soon as possible and within 5 days after the missed dose. If more than 5 days have passed, you should skip the missed dose, and the next dose should be administered on the regularly scheduled day. After this you can resume your regular once weekly dosing schedule. If more than one dose is missed, you may need to consider reducing your starting dose for re-initiation as you may experience side effects. Consult your healthcare provider in this case if you were currently using a pen of strength 0.5mg / 1mg / 1.7mg / 2.4mg. If you missed a dose on the 0.25mg weekly strength this is the initiation dose so can be continued.

Side effects can occur with any medication. There are some things that can help prevent side effects during your treatment with Wegovy. Please be aware of the following possible side effects:

Very common (more than 1 in 10 people affected):
Headache, vomiting, diarrhoea, constipation, nausea, abdominal pain, fatigue

Common (less than 1 in 10 but more than 1 in 100):
Hypoglycaemia in Type 2 diabetics, dizziness, diabetic retinopathy in Type 2 diabetics, gastritis, gastro-oesophageal reflux disease, dyspepsia, eructation, flatulence, abdominal distention, cholelithiasis (gallstones), hair loss, injection site reactions

Uncommon (less than 1 in 100 but more than 1 in 1000)
Increased heart rate, acute pancreatitis, increased enzymes (amylase/lipase)

If you are experiencing any concerning side effects, you can contact a GP immediately or contact NHS 111 (call 111 or visit https://111.nhs.uk/). You can report any side effects not listed above to your clinician. In particular, if you are experiencing milder side effects and these are becoming intolerable, contact your clinician for support with your ongoing weight management journey. If you are a current Wegovy patients of ours, you can contact us via email at: wl@sussexmedicalchambers.co.uk and we will pass on your query within our team.

Please note that you can also report side effects from using Wegovy as a member of the public to the Medicines and Healthcare products Regulatory Agency which helps to ensure its safe and effective use. This is via the Yellow Card scheme https://yellowcard.mhra.gov.uk/ . However, if you need current medical support with your side effects then contact your clinician.

• Acute Pancreatitis
  An uncommon side effect of Wegovy is acute pancreatitis. This is where the pancreas can become swollen over a short period of time.
  If you experience any of the following symptoms of acute pancreatitis you should stop using Wegovy (semaglutide) and contact a GP immediately or contact NHS 111 (call 111 or visit https://111.nhs.uk/):

• Severe pain in the centre of the belly/abdomen. This can worsen and travel along the back
• Nausea/vomiting
• Indigestion
• Fever (>38 degrees celsius)
• Yellowing of the eyes
• Yellowing of the skin
• Tenderness in the belly/abdomen or swelling
• Faster heart rate (tachycardia) or rapid breathing
• Dehydration
  There is a risk of dehydration due to reactions of the gastrointestinal system to semaglutide. Ensure you drink plenty of fluids and stay hydrated to avoid depletion
• Dizziness
  Using Wegovy and increasing your dosage may cause dizziness. You should exercise caution with driving or use of machines. See also above to ensure you are hydrated.

Your dietitian lead personalised plan will include guidance on how to eat a balanced diet to improve the likelihood of weight loss.

The Eatwell Guide shows that to have a healthy, balanced diet, people should try to:

• eat at least 5 portions of a variety of fruit and vegetables every day
• base meals on higher fibre starchy foods like potatoes, bread, rice or pasta
• have some dairy or dairy alternatives (such as soya drinks)
• eat some beans, pulses, fish, eggs, meat and other protein
• choose unsaturated oils and spreads, and eat them in small amounts
• drink plenty of water (at least 6 to 8 glasses a day)

Wegovy (semaglutide) and Mounjaro (tirzepatide) should not be used during pregnancy. If you become pregnant while using either medication, you should stop treatment immediately and inform your GP or prescribing clinician.

Both medications should not be used while breastfeeding, as it is not known whether they pass into breast milk or what effect they may have on the infant.

Women who are planning a pregnancy should not use:

• Wegovy (semaglutide) for at least 2 months before planned conception

• Mounjaro (tirzepatide) for at least 1 month before planned conception

This allows sufficient time for the medication to be cleared from the body.

For women of childbearing age, it is strongly advised to use an effective form of contraception while using Wegovy or Mounjaro.

You can see more about your contraceptive choices here.