By Anna Fenech, Pharmacist Independent Prescriber
A pharmacist’s guide to weight loss injections in the UK, including Mounjaro, Wegovy, eligibility, costs, side effects and how to start.
If you have been searching for weight loss injections in the UK, you will probably have come across Mounjaro and Wegovy.
These prescription medicines have become an important option for people living with obesity, particularly when changes to diet and physical activity have not been enough on their own. They can reduce appetite, help you feel fuller after eating and make it easier to maintain a lower calorie intake.
But starting treatment is not simply a case of choosing a pen and ordering it online. Your medical history, current medicines, BMI, previous treatment and individual circumstances all need to be considered.
As a pharmacist independent prescriber, I know that people often have very practical questions before starting. Which injection is right for me? How much does it cost? What side effects should I expect? Will I have to take it forever?
This guide covers those questions and explains how weight loss injections work, who they may be suitable for and what to consider before starting treatment.
What are weight loss injections?
Weight loss injections are prescription medicines used alongside a reduced-calorie diet and increased physical activity to support weight management.
The two medicines currently offered through Direct Weight Loss are Mounjaro (tirzepatide) and Wegovy (semaglutide). Both are administered once a week.
They belong to a group of medicines known as incretin-based treatments. Wegovy acts on the GLP-1 receptor, while Mounjaro acts on both the GLP-1 and GIP receptors.
The important point for patients is what this means in practice: these medicines influence appetite and fullness. Many people find that they feel less hungry, become satisfied with smaller portions and experience fewer food cravings.
They are licensed medicines for specific medical conditions, rather than cosmetic slimming products. The MHRA advises that GLP-1 medicines should only be used within their authorised indications and following appropriate medical assessment.
How do weight loss injections work?
How Mounjaro works
Mounjaro contains tirzepatide, which activates two hormone receptors: GLP-1 and GIP.
These hormones are involved in appetite regulation, digestion and blood glucose control. By acting on both pathways, tirzepatide can reduce appetite and increase feelings of fullness.
Mounjaro is injected once a week. Treatment starts at a low dose and is gradually increased when appropriate. This gradual approach is important because gastrointestinal side effects are more common when starting treatment or increasing the dose.
How Wegovy works
Wegovy contains semaglutide, a GLP-1 receptor agonist.
GLP-1 is a hormone naturally released after eating. Among other effects, it helps regulate appetite and contributes to feelings of fullness.
Wegovy works by mimicking this hormone, helping many patients eat less without experiencing the same level of hunger they may have felt previously.
Wegovy is also taken once a week.
The MHRA approved a 7.2 mg Wegovy dose in April 2026 for adults with obesity. This does not mean everyone taking Wegovy should increase to that dose. Dose changes should only be made according to the prescribing instructions and advice of your healthcare professional.
Mounjaro vs Wegovy: what is the difference?
Mounjaro and Wegovy are both used for weight management, but they contain different active ingredients and work through different hormone pathways.
| Mounjaro | Wegovy | |
|---|---|---|
| Active ingredient | Tirzepatide | Semaglutide |
| Action | GIP and GLP-1 | GLP-1 |
| Administration | Once-weekly injection | Once-weekly injection |
| Used for weight management | Yes | Yes |
There is not one medicine that is automatically right for everyone.
When I assess someone for treatment, I look at the wider clinical picture rather than simply asking which medicine they would prefer. Medical history, other medicines, previous treatment, BMI, side effects and individual goals all have a bearing on the decision.
What about Foundayo?
There is a newer medicine worth knowing about if you have been researching weight management in the UK.
Foundayo contains orforglipron, an oral GLP-1 receptor agonist. Unlike Mounjaro and Wegovy, it is taken as a tablet rather than an injection.
The MHRA authorised orforglipron for weight management in the UK in August 2026. It can be used alongside a reduced-calorie diet and increased physical activity in adults with obesity, or in adults who are overweight and have at least one weight-related health problem.
Foundayo is therefore relevant to the wider conversation around prescription weight loss medicines, particularly for people interested in an oral option.
It is important not to confuse it with Mounjaro or Wegovy. They are different medicines, with different dosing schedules and prescribing considerations.
Who is eligible for weight loss injections in the UK?
Eligibility depends on the medicine and your individual circumstances.
At Direct Weight Loss, the published programme is available to adults aged 18 to 75 who meet the relevant criteria. These include:
- a BMI of 30 or above, or
- a BMI of 27 or above with a weight-related health condition.
Examples of weight-related conditions can include high blood pressure, abnormal blood lipid levels and obstructive sleep apnoea.
Meeting a BMI threshold does not automatically mean that a particular medicine is suitable.
Your prescriber will also need to consider your medical history, current medication, previous treatment and any contraindications or precautions that apply.
This is why a proper consultation matters.
What happens during a weight loss consultation?
One of the things I consider particularly important is that the consultation should be a genuine clinical assessment, rather than a tick-box exercise.
At Direct Weight Loss, the process begins with a medical questionnaire. A pharmacist reviews the information provided and assesses whether you may be suitable for treatment.
If there are no obvious contraindications, you are invited to an online one-to-one consultation. During this appointment, your pharmacist can discuss the available treatment, answer questions and create an appropriate plan. The service also asks patients to check their weight and measure their waist circumference at home.
If treatment is prescribed, the medication is supplied through a registered UK pharmacy and delivered to your home. Direct Weight Loss also provides a supervised video call for the first injection so that you can be shown how to administer it correctly.
If you are considering weight loss treatment, this type of clinical support is worth looking for. You should know what you are taking, why it has been prescribed and what to do if you develop side effects.
How much do weight loss injections cost in the UK?
Private prices vary between providers, so it is sensible to look at the full cost rather than comparing one headline figure.
At Direct Weight Loss, the currently published prices for individual pens are:
Mounjaro prices
- 2.5 mg: £169.99
- 5 mg: £185.99
- 7.5 mg: £236.99
- 10 mg: £260.99
- 12.5 mg: £277.99
- 15 mg: £297.99
Wegovy prices
- 0.25 mg: £119.99
- 0.5 mg: £124.99
- 1 mg: £129.99
- 1.7 mg: £169.99
- 2.4 mg: £220.99
Direct Weight Loss also currently advertises weight loss consultations from £89.99. Its published treatment pricing states that medication is supplied alongside additional resources to support the weight loss programme.
Prices can change, so it is always worth checking the current price before ordering.
What side effects can weight loss injections cause?
The most common side effects are gastrointestinal.
You may experience:
- nausea
- vomiting
- diarrhoea
- constipation
- abdominal discomfort
- reduced appetite.
These effects are often more noticeable when treatment starts or after a dose increase. For many people they settle as the body becomes accustomed to the medicine.
That does not mean you should simply put up with severe or persistent symptoms. If you are struggling with side effects, contact your prescriber. Sometimes a slower approach to dose escalation or additional advice about eating and drinking can make a significant difference.
The MHRA advises that nausea, vomiting and diarrhoea can occasionally lead to dehydration and, in more serious cases, hospital treatment.
Can weight loss injections cause pancreatitis?
Acute pancreatitis is an uncommon but recognised side effect of GLP-1 receptor agonists and dual GLP-1/GIP receptor agonists.
In January 2026, the MHRA strengthened its warnings following reports of acute pancreatitis, including rare cases of severe, necrotising and fatal pancreatitis.
The symptom I would particularly want patients to recognise is severe, persistent abdominal pain, especially if it spreads towards the back and is accompanied by nausea or vomiting.
If this happens, seek urgent medical attention.
If pancreatitis is suspected, treatment should be discontinued while it is investigated. If pancreatitis is confirmed, the medicine should not be restarted.
This is one reason I would strongly recommend obtaining weight loss medicines through a properly regulated prescribing service rather than an unverified seller.
Are weight loss injections safe?
For people who are appropriately assessed and prescribed the correct medicine, Mounjaro and Wegovy are established treatments for weight management.
But every medicine has risks.
The MHRA continues to monitor these medicines and update safety information as evidence develops. In 2026, for example, the regulator highlighted the very rare risk of NAION, a condition affecting the optic nerve, in people taking semaglutide. Anyone taking semaglutide who experiences sudden vision loss should seek urgent medical assessment.
There are also practical safety issues to consider. Prescription weight loss medicines should not be bought from unregulated websites or social media sellers. The MHRA has warned about illegal and falsified weight loss medicines, including falsified Mounjaro pens identified in the UK.
A legitimate UK prescribing service should be able to tell you who is prescribing your medication, where it is dispensed and how you can obtain help if you have a problem.
Do I need to change my diet while taking weight loss injections?
Yes.
Medication is a tool to support weight management, not a substitute for eating well.
As your appetite decreases, the type of food you choose becomes particularly important. You may be eating less overall, so meals need to provide useful nutrition.
I generally encourage patients to focus on:
- adequate protein
- vegetables and other sources of fibre
- sensible portions
- regular fluid intake
- limiting highly processed, calorie-dense foods
- eating slowly and stopping when comfortably full.
You do not need to starve yourself to make the medication work.
In fact, trying to force rapid weight loss by severely restricting food or increasing your medication dose without medical advice can be counterproductive and unsafe. The MHRA specifically advises patients not to increase their dose in an attempt to accelerate weight loss.
How quickly will I lose weight?
This varies considerably between individuals.
Some people notice that their appetite changes within the first few weeks. The amount of weight lost over time depends on factors including the medicine and dose, starting weight, diet, physical activity, underlying health conditions and how your body responds.
I would be cautious about anyone promising a fixed amount of weight loss each week.
Direct Weight Loss itself notes that results vary between patients and are influenced by diet, activity levels and individual metabolism.
The goal should be steady, sustainable progress rather than trying to make the number on the scales fall as quickly as possible.
What happens when I reach my target weight?
This is an important conversation to have before starting.
Weight management does not necessarily end when you reach a particular number on the scales. Appetite can return if medication is stopped, and some people regain weight after discontinuing treatment.
For some patients, ongoing treatment may be appropriate. For others, a planned reduction or stopping treatment alongside continued lifestyle support may be considered.
There is no single maintenance plan that suits everyone. Your prescriber should review your progress and help you decide what makes sense for your circumstances.
How do I get started with weight loss injections?
Start with an assessment rather than choosing a medicine based solely on price or online reviews.
At Direct Weight Loss, the process is designed around clinical assessment:
- Complete the initial medical questionnaire.
- Have your information reviewed by a healthcare practitioner.
- Attend an online one-to-one consultation if you appear suitable.
- Discuss your treatment options and agree on an appropriate plan if prescribing is suitable.
- Receive your medication by discreet delivery from a registered UK pharmacy.
- Have support with your first injection through a one-to-one video call.
The service also provides ongoing support and check-ins, rather than simply sending medication and leaving you to manage the treatment yourself.
What should I look for when choosing a weight loss provider?
Price is important, particularly because private treatment can be a long-term expense. But I would not make it the only consideration.
Before choosing a provider, check:
- who will prescribe your medicine
- whether the prescriber is appropriately registered
- which pharmacy will dispense it
- whether the medication is UK-licensed
- whether you receive a proper medical assessment
- what follow-up support is available
- who you can contact if you develop side effects
- whether you receive clear instructions for using the injection.
For an online service, these details matter because you should still receive the same standard of clinical care you would expect from any other healthcare professional.
Frequently asked questions
What are the best weight loss injections in the UK?
The two treatments currently offered by Direct Weight Loss are Mounjaro and Wegovy. Both are licensed medicines for weight management, but they work differently and may not be equally suitable for every patient.
Is Mounjaro or Wegovy better for weight loss?
There is no universally appropriate answer. Mounjaro contains tirzepatide and acts on both GIP and GLP-1 receptors, while Wegovy contains semaglutide and acts on GLP-1 receptors. The appropriate choice depends on your individual clinical circumstances.
Are weight loss injections available privately in the UK?
Yes. Mounjaro and Wegovy can be prescribed privately to eligible patients following an appropriate clinical assessment.
How much do weight loss injections cost?
Private prices vary. At Direct Weight Loss, currently published prices range from £119.99 for a 0.25 mg Wegovy pen to £297.99 for a 15 mg Mounjaro pen, with consultation fees applying separately.
Are weight loss injections available on the NHS?
Some weight management medicines are available through the NHS for eligible patients, but NHS access depends on the relevant clinical criteria and local service arrangements. Private prescribing has different eligibility and access arrangements.
Is Foundayo an injection?
No. Foundayo is the brand name for orforglipron, a once-daily oral GLP-1 medicine. The MHRA authorised it for weight management in the UK in August 2026.
Can I take Mounjaro or Wegovy with another weight loss medicine?
Do not combine prescription weight loss medicines unless your prescriber has specifically advised you to do so. Combining medicines that affect similar appetite and metabolic pathways can increase the risk of side effects and may not be appropriate.
Do weight loss injections hurt?
The injection uses a very fine needle and most people find administration straightforward. Direct Weight Loss provides a supervised first-dose video call to demonstrate how to use the pen correctly.
Do I have to fast while taking weight loss injections?
No. Fasting is not a requirement of the Direct Weight Loss programme.
Can I take weight loss injections if I have other medical conditions?
Possibly, but it depends on the condition and your medication. This is something that needs to be assessed during your consultation. Always provide a complete and accurate medical history before a prescription is issued.
Final thoughts
Weight loss injections can make a meaningful difference for people who meet the clinical criteria for treatment, but they work best when they are part of a properly managed weight management plan.
Mounjaro and Wegovy are currently the main injection options offered through Direct Weight Loss. Foundayo is a newer oral option that has also been authorised in the UK, although it is not an injection.
The right starting point is not simply choosing the medicine with the most attention online. It is understanding whether treatment is appropriate for you, what the potential benefits and risks are, how much it will cost and what support you will receive along the way.
Anna Fenech is a pharmacist independent prescriber and the founder of Direct Weight Loss.