Mounjaro® and Wegovy® for Weight Loss: A Complete Guide to GLP-1 Weight Management Medicines in the UK

Introduction

Weight management can be challenging, and for many people living with obesity, losing weight is not simply a matter of willpower or making short-term changes to diet and exercise.

Obesity is recognised as a chronic health condition that can affect many aspects of health, including the risk of developing conditions such as type 2 diabetes, high blood pressure, cardiovascular disease, sleep apnoea and joint problems.

For some people, lifestyle changes alone may not lead to sufficient or sustained weight loss. In these situations, healthcare professionals may consider additional treatment options, including prescription weight management medicines alongside dietary changes, increased physical activity and long-term lifestyle support.

In recent years, medicines that work on appetite regulation pathways, including Mounjaro® (tirzepatide) and Wegovy® (semaglutide), have gained attention as options for managing obesity in suitable patients.

These medicines do not replace healthy lifestyle changes. Instead, they are designed to support people by influencing the body's natural appetite and metabolic pathways.

At Wallis Jones Pharmacy, our approach is focused on safe, evidence-based weight management support, including assessment, monitoring, lifestyle advice and ongoing pharmacist guidance where appropriate.

Understanding obesity

What is obesity?

Obesity is a condition where excess body fat can negatively affect health. Healthcare professionals commonly use Body Mass Index (BMI) as one measurement when assessing weight status.

BMI is calculated using weight (kg) ÷ height² (m²).

However, BMI is not the only factor considered. Healthcare professionals may also consider:

• Waist circumference
• Existing health conditions
• Family history
• Lifestyle factors
• Previous weight management attempts
• Medicines that may affect weight

Why can losing weight be difficult?

Weight regulation involves complex interactions between the brain, hormones, appetite signals, metabolism, genetics, environment, and behaviour and lifestyle factors.

When someone loses weight, the body may respond by increasing hunger signals and reducing energy expenditure. This can make maintaining weight loss difficult.

GLP-1 (glucagon-like peptide-1)

GLP-1 is naturally produced in the body after eating. It helps:

• Increase feelings of fullness
• Slow stomach emptying
• Regulate blood glucose levels
• Influence appetite signals in the brain

GIP (glucose-dependent insulinotropic polypeptide)

GIP is another hormone released after meals. It is involved in insulin regulation, glucose metabolism and energy balance.

Medicines such as semaglutide and tirzepatide work by mimicking some of these natural hormone effects.

What are GLP-1 weight management medicines?

GLP-1 receptor agonists are a group of medicines originally developed for managing type 2 diabetes. Research showed that these medicines can also support weight management by affecting appetite control and metabolism.

Reducing appetite

Many people taking these medicines report feeling less hungry and becoming full more quickly.

Increasing feelings of fullness

Food may remain in the stomach for longer, helping some people feel satisfied after smaller meals.

Supporting blood glucose regulation

These medicines can improve how the body responds to changes in blood sugar levels.

What is Mounjaro®?

Mounjaro contains the active ingredient tirzepatide. It belongs to a newer class of medicines known as a dual GIP and GLP-1 receptor agonist.

Unlike medicines that target only GLP-1, tirzepatide works on two hormone pathways — the GIP receptor pathway and the GLP-1 receptor pathway. This dual action helps regulate appetite and metabolism.

How does Mounjaro work?

1. Reducing appetite — it affects areas of the brain involved in appetite regulation, which may reduce hunger and cravings.
2. Improving feelings of fullness — patients may feel satisfied with smaller portions.
3. Supporting metabolic health — it can improve insulin sensitivity and help regulate blood glucose.

How is Mounjaro taken?

Mounjaro is administered as a once-weekly injection. Treatment usually begins with a lower dose, which is gradually increased over time if appropriate.

The gradual dose escalation is used to help reduce gastrointestinal side effects such as nausea, vomiting, diarrhoea, constipation and abdominal discomfort.

Who may be considered for Mounjaro?

Suitability depends on several factors, including BMI, weight-related health conditions, medical history, current medicines and previous weight management attempts.

Not everyone who wants to lose weight will be suitable for prescription weight management medicines. A healthcare professional should assess whether treatment is appropriate and safe.

What is Wegovy®?

Wegovy® contains the active ingredient semaglutide. It belongs to a group of medicines called GLP-1 receptor agonists.

GLP-1 is a naturally occurring hormone released after eating. It plays an important role in regulating appetite, feelings of fullness, blood glucose levels and digestion.

Wegovy works by mimicking the effects of GLP-1, helping some people feel fuller after eating and reducing hunger signals. Like all prescription weight management medicines, Wegovy should be used as part of a wider weight management plan that includes dietary support, physical activity and lifestyle changes.

How does Wegovy work?

1. Appetite regulation

Semaglutide acts on areas of the brain involved in appetite control. Some patients report reduced hunger, fewer food cravings and feeling satisfied with smaller portions.

2. Slower stomach emptying

GLP-1 medicines can slow the movement of food from the stomach into the intestine. This may help some people feel fuller for longer after meals.

3. Blood glucose regulation

GLP-1 medicines can help regulate glucose levels by influencing insulin and glucagon activity. This is particularly relevant for people who also have conditions such as prediabetes or type 2 diabetes.

How is Wegovy taken?

Wegovy is administered as a once-weekly injection. Treatment usually follows a gradual dose escalation schedule, increased over time where appropriate to improve tolerability and reduce the likelihood of side effects.

Common side effects during dose increases may include nausea, constipation, diarrhoea, vomiting and abdominal discomfort. The dose schedule should always follow the approved product information and clinical assessment.

Mounjaro® vs Wegovy®: what is the difference?

Which is more effective: Mounjaro® or Wegovy®?

Clinical studies have shown that both medicines can support meaningful weight reduction in suitable patients. However, results vary between individuals.

Factors affecting outcomes include:

• Starting weight
• Diet quality
• Physical activity levels
• Dose reached
• Treatment adherence
• Individual response to treatment
• Existing health conditions

A medicine that works well for one person may not be the best option for another. The choice of treatment should consider medical history, current medicines, side effect risk, patient preference and clinical suitability.

Who may be suitable for weight loss medication?

Weight loss medicines are not suitable for everyone. A healthcare professional will consider factors such as:

Body Mass Index (BMI)

BMI is one factor used when assessing eligibility.

Weight-related health conditions

• High blood pressure
• Abnormal cholesterol levels
• Obstructive sleep apnoea
• Cardiovascular disease
• Prediabetes
• Type 2 diabetes

Previous weight management attempts

Healthcare professionals may consider previous efforts involving diet changes, physical activity and behavioural support.

NICE recommendations include specific eligibility criteria depending on the medicine being considered. For example, NICE guidance for tirzepatide includes BMI thresholds and weight-related comorbidities when used for managing overweight and obesity.

Who may not be suitable?

A clinical assessment is essential because these medicines may not be appropriate for everyone. Important considerations include:

• Pregnancy or planning pregnancy
• Breastfeeding
• Previous reactions to the medicine
• Certain gastrointestinal conditions
• History of pancreatitis
• Other medicines being taken
• Personal medical history

Patients should always discuss suitability with a qualified healthcare professional.

Starting your weight management journey with Wallis Jones Pharmacy

A pharmacist-led weight management service should focus on safe, structured care. A typical consultation may include:

Initial assessment

• Height
• Weight
• BMI calculation
• Medical history
• Current medicines
• Lifestyle assessment
• Previous weight management attempts

Treatment discussion

The pharmacist can discuss available treatment options, benefits and limitations, possible side effects and lifestyle support.

Ongoing monitoring

Regular reviews help assess weight progress, side effects, treatment response, lifestyle changes and whether treatment remains appropriate.

The aim is not simply weight loss, but improving long-term health outcomes.

Wegovy® tablets: the oral option for weight management

Wegovy® tablets contain the active ingredient semaglutide, the same active ingredient used in Wegovy injection treatment. Unlike the injectable version, Wegovy tablets are taken by mouth once daily.

They belong to the same medicine group as injectable GLP-1 receptor agonists and work by mimicking the body's natural GLP-1 hormone pathway. The MHRA approved the oral semaglutide formulation of Wegovy for weight management in adults who meet appropriate criteria, alongside a reduced-calorie diet and increased physical activity.

How do Wegovy® tablets work?

Wegovy tablets work in a similar way to injectable semaglutide. They may help by reducing appetite (acting on areas of the brain involved in appetite regulation), increasing feelings of fullness by slowing stomach emptying, and supporting metabolic health by influencing glucose regulation and insulin response.

How are Wegovy® tablets taken?

Unlike the weekly injection, Wegovy tablets are taken once daily and the dose is gradually increased over time. This gradual increase helps the body adjust and may reduce gastrointestinal side effects.

The oral formulation uses specific technology to allow semaglutide to be absorbed when taken by mouth. Patients should follow the administration instructions carefully because how the tablet is taken can affect absorption.

1. On an empty stomach

The tablet should be taken after a fasting period of at least 8 hours. This means it is usually taken in the morning before eating or drinking anything.

2. Swallowed whole with water

The tablet should be swallowed whole with no more than half a glass of water (up to approximately 120 mL). Do not split, crush or chew the tablet, because altering it may affect how semaglutide is absorbed and the impact of doing so is not known.

3. Wait before eating, drinking or taking other medicines

After taking Wegovy tablets, patients should wait at least 30 minutes before eating food, drinking anything other than water, or taking other oral medicines. Doing any of these sooner may reduce the absorption of semaglutide.

Both options require clinical assessment, lifestyle support, monitoring, and review of effectiveness and tolerability.

Are Wegovy tablets better than the injection?

Not necessarily. The best option depends on the individual patient. Some people prefer tablets because they do not want injections or find daily routines easier; others prefer weekly injections because they do not need to remember a daily tablet.

A healthcare professional should consider patient preference, medical history, other medicines, ability to follow administration instructions and treatment goals.

Can you switch between Mounjaro® and Wegovy® tablets?

Switching between weight management medicines should only happen after a clinical review. Patients should not independently change from one medicine to another.

A healthcare professional will consider the current dose, previous side effects, treatment response, the reason for changing treatment and the appropriate starting dose of the new medicine. A lower starting dose may be required when changing treatments to improve tolerability.

Common side effects

Because these medicines affect appetite and digestion, the most common side effects involve the gastrointestinal system. Most side effects are mild to moderate and are often most noticeable when treatment is started or when the dose is increased.

Nausea

This is particularly common when starting treatment or increasing the dose. Helpful strategies may include eating smaller meals, avoiding very fatty foods, eating slowly, maintaining hydration and avoiding lying down immediately after eating.

Some people also find that ginger products, such as ginger tea, ginger biscuits, crystallised ginger or ginger capsules, may help relieve mild nausea. If nausea is persistent, severe or prevents you from eating or drinking adequately, speak to your pharmacist or healthcare professional.

Constipation

Some patients experience constipation because of reduced food intake and slower digestion. Helpful measures include drinking enough fluids, eating fibre-containing foods where appropriate and staying physically active. Your pharmacist can recommend suitable treatments if needed.

Diarrhoea

This may occur, especially during dose increases. Drink extra fluids, consider oral rehydration solutions if appropriate, and continue eating small, simple meals. Seek advice if diarrhoea is severe, prolonged or associated with dehydration.

Vomiting

Occasional vomiting may occur, particularly after dose increases. Persistent vomiting should be discussed with a healthcare professional, especially if there is difficulty maintaining fluids.

Burping, indigestion and bloating

Eating smaller meals and avoiding large quantities of fatty food may help reduce these symptoms.

When should you seek medical advice?

Contact your pharmacist, prescriber or healthcare professional if you experience:

• Persistent vomiting or inability to keep fluids down
• Signs of dehydration
• Severe or ongoing abdominal pain
• Symptoms that concern you or are worsening
• Significant changes in your health while taking treatment

Living well while taking Mounjaro® or Wegovy®

Starting a weight management medicine is only one part of the journey. Long-term success is usually achieved by combining medication with sustainable lifestyle changes, ongoing support and regular reviews. These medicines are designed to support healthier eating habits — not to replace them.

Focus on protein

Protein helps support muscle maintenance during weight loss, feelings of fullness, recovery after physical activity and general health. Good sources include:

• Skinless chicken or turkey
• Fish and seafood
• Eggs
• Greek yoghurt and cottage cheese
• Tofu and tempeh
• Lentils, chickpeas and beans
• Quorn® products
• Unsalted nuts and seeds (in moderation)

If your appetite is low, prioritising protein-rich foods first at meals may help ensure adequate intake.

Stay hydrated

Reduced appetite can sometimes mean people drink less without realising it. Aim to drink fluids regularly throughout the day unless advised otherwise. Good hydration may also help reduce constipation, headaches, fatigue and dizziness.

Eat smaller, balanced meals

Large meals may increase the likelihood of nausea or discomfort. Many patients find it easier to eat smaller portions, more slowly, and more frequently if needed — stopping when comfortably full rather than finishing every meal. A balanced plate may include a protein source, vegetables or fruit, high-fibre carbohydrates and healthy fats.

Foods that may worsen symptoms

Some people notice that fried foods, greasy meals, very spicy foods, large takeaway meals, sugary desserts and fizzy drinks increase nausea or indigestion. These do not need to be completely avoided unless advised, but reducing them during the first few weeks may improve comfort.

Alcohol

Alcohol is not specifically prohibited for most people taking these medicines. However, it may worsen nausea, increase the risk of dehydration, add unnecessary calories and make healthy eating goals more difficult. If alcohol consistently worsens side effects, discuss this with your healthcare professional.

Exercise during treatment

Physical activity helps preserve muscle mass, improve cardiovascular health, support mental wellbeing and maintain weight loss. Many people start with walking, swimming, cycling, resistance exercises or bodyweight strength training. Choose activities you enjoy and can continue long term.

Travelling with your medication

• Plan ahead and ensure you have enough medication for your trip.
• Follow the manufacturer's storage recommendations.
• Carry medicines in your hand luggage where appropriate if flying.
• If travelling abroad, check whether you need supporting documentation for prescription medicines.

Can I take other medicines?

Always tell your pharmacist or prescriber about all medicines you take, including prescription medicines, over-the-counter medicines, herbal remedies, and vitamins and supplements. Some medicines may require additional monitoring or timing adjustments while you are taking GLP-1 medicines.

Pregnancy and breastfeeding

These medicines are not recommended during pregnancy. If you become pregnant or are planning a pregnancy, speak to your healthcare professional promptly. Women of childbearing potential should discuss contraception and pregnancy planning before starting treatment, in line with current product information. These medicines are also generally not recommended while breastfeeding.

What happens if you stop treatment?

Weight management is a long-term process. When weight loss medication is stopped, some people may regain weight, because appetite signals may return, the body naturally tries to restore previous weight, and lifestyle habits may need ongoing support.

For this reason, healthcare professionals place significant emphasis on developing sustainable eating habits, physical activity and behavioural changes while taking medication. Any decision to stop treatment should be discussed with your pharmacist or prescriber so that ongoing weight management support can be planned.

How Wallis Jones Pharmacy supports your weight management journey

We understand that weight management involves more than simply choosing a medicine. Our pharmacist-led approach focuses on safe, evidence-based support throughout your journey.

Initial assessment

We will discuss your current weight and health goals, medical history, current medicines, previous weight management attempts, lifestyle factors and suitability for treatment.

Treatment discussion

If weight management medication is clinically appropriate, we can discuss how the medicine works, expected benefits, possible side effects, how to take the medication correctly and lifestyle support alongside treatment.

Ongoing reviews

Reviews may include discussion of weight progress, side effects, treatment adherence, lifestyle changes and any concerns or questions.

Why choose a pharmacist-led weight management service?

Community pharmacists are highly trained healthcare professionals who are accessible and experienced in medicines optimisation, side-effect management, lifestyle advice, monitoring treatment safety and supporting long-term health goals.

Frequently asked questions

Key takeaways

• Mounjaro® and Wegovy® are prescription medicines used as part of a wider weight management programme.
• They work by influencing appetite and metabolic pathways that affect hunger, fullness and glucose regulation.
• These medicines work best alongside lifestyle changes — healthy eating, physical activity, adequate protein intake and sustainable habits remain essential.
• Treatment suitability is individual: a medicine that is suitable for one person may not be suitable for another.
• Side effects are possible, mostly digestive, and are often most noticeable when starting treatment or increasing doses.
• Ongoing support matters — regular reviews help ensure treatment remains safe, effective and appropriate.