Authored: 19/06/2022
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Weight Loss Injections
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UK pharmacy
At Simple Online Pharmacy you can buy the latest and most effective weight loss injections online, from our UK registered service.
Simply complete the online assessment and our doctor will review your assessment and prescribe your treatment, if it is appropriate.
Our pharmacy will then dispatch your medication securely and discreetly direct to your door.
Mounjaro and Wegovy are designed to help you with your weight in conjunction with healthy eating and a weight loss plan.
Saxenda is also still available in the UK, but has been passed in effectiveness by both Wegovy and Mounjaro. Weight loss pills are also available to buy.
Weight Loss Injections treatment options
Order within for guaranteed next day delivery options
Order within for guaranteed next day delivery options
Order within for guaranteed next day delivery options
Order within for guaranteed next day delivery options
Overview
What are Weight Loss Injections?
Weight loss injections have become a transformative solution for managing obesity. They offer a clinically backed, non-surgical approach to appetite control and weight reduction.
Their rapid adoption in the UK and across the globe, has been driven by strong scientific evidence. In addition, increasing awareness of obesity as a medical condition and the convenience of online prescriptions, has increased use of these treatments.
By supporting sustainable weight loss and improving metabolic health, these treatments have had a significant impact, helping individuals achieve better long-term health outcomes.
Mounjaro, Wegovy and Saxenda are all weight loss injections designed to help assist with weight loss alongside diet and exercise. For the best results, create a weight loss plan that includes healthy eating, physical activity, and weight loss pills and injections only if necessary to help reach a healthy weight.
There are a number of different injection pens used for weight loss in the UK. These are a relatively new type of treatment for weight loss, with the first well known treatment being Saxenda, released in the UK in 2020.
These treatments can support with weight loss between an average of 10% - 22.5% body weight loss.
The following is a summary of the main weight loss injections currently available in the UK.
How do they work?
GLP-1 treatments help you lose weight in 3 key ways.
- Reduce Hunger: Help control appetite, making it easier to eat less.
- Slow Digestion: Keeps you feeling full for longer, so you’re less likely to overeat.
- Balance Hormones: Regulates blood sugar levels and energy use, improving how your body processes food.
These combined effects make managing weight more sustainable. If you’re considering this treatment, complete our online assessment to see if it’s the right fit for you.
Treatment Options
Wegovy
A type of weight loss medication in the UK, Wegovy is an injectable medicine which can help achieve ~15-17% body weight loss on average. This medicine is used much like insulin and comes in an injectable pen that’s injected into the fat under the skin once weekly.
It contains the active ingredient semaglutide, which works by regulating the way the body naturally gets hungry. Changing your appetite leads to eating few calories and a better chance of weight loss.
Clinical trials show that Wegovy helps the average patient lose as much as 15-17% of their body weight. The treatment will potentially revolutionise weight loss treatment across the globe and help many patients with their weight management.
Wegovy also offers added heart protection, with research showing a 20% reduction in cardiovascular events, in patients with previous underlying disease, which is independent of weight loss.
Wegovy dose is started low and increased slowly up to the maintenance dose. It can only be prescribed to patients with a BMI of over 30 or >27.5 with other risk factors at a doctor’s discretion.
Side effects of this weight loss injection include:
- Nausea
- Vomiting
- Diarrhoea or constipation
Mounjaro
Mounjaro is the latest of the weight loss injection pens. It is also the most effective in clinical trials, with an average body weight loss of ~22.5%.This compares to 10% in Saxenda, and 15% in Wegovy and Ozempic.
Mounjaro contains the active ingredient Tirzepatide.
Like the other weight loss injections, Mounjaro should be started at it's lowest dose and titrated up, to help avoid side effects. The starting dose is 2.5mg and the highest maintenance dose is 15mg. It is a once weekly injection.
Saxenda
Saxenda is the original weight loss pen which has been available in the UK since 2020. This treatment has shown that the average patient will achieve around 10% body weight loss over the course of treatment.
This treatment contains the active ingredient liraglutide. This is a sister drug of semaglutide, and both belong to a group of drugs called GLP-1 agonist.
Saxenda is a very similar injection to Wegovy, except it is used once daily instead of once weekly. It works in the same way, suppressing the appetite to reduce eating to assist with losing weight. It is prescribed to patients with A BMI of over 30 or above 27.5 with additional risk factors, just like Wegovy.
Ozempic
Ozempic is perhaps the most well-known of the weight loss injection pens, however, it's not actually licensed for weight loss! In the UK, Ozempic is licensed in the treatment of diabetes. Despite this, it is effective in helping patients lose weight, and as a result, many doctors do prescribe Ozempic off licence (a legal practice), to patients.
Ozempic, like Wegovy, contains the active ingredient semaglutide.
Because Ozempic is primarily a drug used in diabetes, we choose not to prescribe this, so as not to affect critical supply chains for diabetic patients.
Weight Loss Injection Summary
| Feature | Mounjaro | Wegovy | Saxenda | Ozempic |
|---|---|---|---|---|
| Licensed for weight loss? | Yes | Yes | Yes | No |
| How much weight can I lose? | Up to 22.5% | Up to 14.9% | Up to 6.3% | Not for weight loss |
| When does it start working? | A few weeks | A few weeks | A few days | A few days |
| Active ingredient | Tirzepatide | Semaglutide | Liraglutide | Semaglutide |
| How it works | Reduces appetite | Reduces appetite | Reduces appetite | For diabetes only |
| Can I buy it online? | Yes | Yes | Yes | No |
| Do I need a prescription? | Yes | Yes | Yes | Yes |
| How is it taken? | Weekly injection | Weekly injection | Daily injection | Weekly injection |
| How long do I take it? | As advised by your doctor | As advised by your doctor | As advised by your doctor | As advised by your doctor |
* In studies, patients lost up to 22.5% of their starting weight after 72 weeks at the 15 mg dose.
** In studies, patients lost up to 14.9% of their starting weight after 68 weeks on the maintenance dose.
*** In studies, patients lost an average of 6.3% of their starting weight after 56 weeks on the maintenance dose.
Weight Loss Pills
A weight-loss treatment we can prescribe is Orlistat (Xenical/ Alli). This medicine stops the body from absorbing 30% of the fat from meals. This reduction in fat absorption reduces overall daily calorie intake. Orlistat is taken before, during or one hour after each major meal.
It may only be prescribed to patients with a BMI of over 30 or >28 with other weight-related conditions.
Orlistat also acts as a deterrent for high-fat foods due to the stomach discomfort experienced if you do eat a high-fat meal.
Side effects may include fat in the stool, poorly smelling stool (due to high-fat content), increased flatulence, floating stools, gastric upset if taken with a high-fat meal.
Visit our Orlistat Page for more information
When Should You Consider Losing Weight?
To understand when it may be time to lose weight you should consider your body mass index (BMI). This tool uses your height and weight to give a number determining how healthy your current weight is.
- Underweight = <18.5
- Healthy range = 18.5 to 24.9
- Overweight = 25-29.9
- Obese = >30
While useful in identifying whether you are carrying too much weight, it does not consider what type of weight this is. BMI will not distinguish the difference between muscle, bone or water weight. It often classes very muscular adults as overweight or very low muscle adults as healthy even when they have high body fat percentages.
For this reason, body fat percentage is a more reliable indicator of obesity. Body fat percentages of over 25% are defined as obese. You can find a guide on measuring your body fat on the BHF website.
Obesity in the UK is a major health concern with 64.2% of UK adults and 37% of children considered overweight or obese.
The Risks of Obesity
Whilst being obese generally does not pose immediate threats to your health, the long-term risks of being overweight or obese are:
- Cardiovascular diseases - high blood pressure, heart attack, stroke
- Sexual dysfunction - women: infertility and irregular menstruation. Men: erectile dysfunction
- Cancer of the uterus, ovary, breast, prostate, liver, colon, oesophagus, and kidney.
- Low self-esteem
- Sleep apnoea
- Osteoarthritis
- Gastro-intestinal diseases
- Certain types of diabetes
What are the Health Benefits of Weight Loss?
The risks of obesity listed above have all have been proven to drop a clinically significant amount with only a 5% drop in weight.
What Causes Weight Gain?
The body will gain weight if the calories taken in by food and drinks exceeds what the body is using. This excess of calories is stored as energy in the form of fat resulting in weight gain.
Poor Diet
Men and women have different nutritional demands per day, and these can vary with age, activity, and health. A diet that fails to meet these demands will result in an unhealthy weight loss. However, in avoiding some of the following you may find it easier to achieve healthy weight loss:
- Fast food - high in saturated fats and refined/added sugars
- Alcohol - high in calories and added sugars
- Overeating - Large portion sizes - you can find a guide to portion sizes on the BDA site
- Sugary drinks- Fresh fruit juices(>150ml), soft drinks, and milkshakes are all high in sugars.
Lack of Exercise
Exercise increases the nutritional demands of the body each day. This plays a large role in balancing whether your body uses or stores fat each day.
Medicines
Side effects of some medicines may cause weight gain. Some examples include:
- Antipsychotics
- Birth control
- Antiepileptics
- Oral corticosteroids
Weight gain that you suspect your current medicines are causing should be discussed with your GP.
Medical Conditions
A number of medical conditions can cause you to gain weight including:
- Cushing’s syndrome
- Depression
- Insomnia
- Hypothyroidism
- Diabetes types 1 and 2
If you believe your medical condition is causing you to gain weight, seek out medical advice for long term treatments for both the underlying condition and weight loss.
Alternatives
Weight Loss Surgery
This is also known as bariatric or metabolic surgery. It is typically used only for the treatment of people who are very obese with few options remaining. The NHS will sometimes cover this surgery for patients if they fit the criteria.
Lap Band
An inflatable band is placed around the stomach creating a small pocket above. Smaller meals then result in you feeling full.
Gastric Bypass
A part of your stomach is attached further down the intestine, thus bypassing a large section where calories are usually absorbed.
Gastric Sleeve
The majority of the stomach is removed during this procedure (80-85%). This smaller stomach requires less food to make you feel full.
Lifestyle Changes to Lose Weight
Diet
Changes to eating habits are the most important changes to make to lose weight. Whilst weight loss can be achieved by keeping the calories used higher than the calories consumed, it is important to be aware that numerous factors contribute to weight changes. This is why at Simple Online Healthcare we promote a holistic approach to weight loss, making your health a priority. Due to your body adapting to this, it can become quite difficult to maintain and potentially lead to a continuous cycle of restriction. That's why modern medicines aim to increase feelings of satiety. This enables you to focus on making the lifestyle changes to achieve long-term results. Short term diet changes may yield good results; however, these are usually short-lived as the weight tends to return after the diet ends and eating habits revert back.
Short term fad diets tend to be unsustainable as they restrict eating to very few food groups which can lead to an unhealthy relationship with food and eating behaviours. The best sustainable solution to long term weight loss is a balanced diet containing an appropriate amount of each food group.
Examples of this can be:-
- Carbohydrates - 2-3 portions per day-
- Protein - 2-3 portions per day (mixing animal and plant sources)-
- Fats - 1-2 portions per day (having healthy plant sources most often and oily fish at least 2x per week).
- Fruit - 1-3 portions per day (great for a quick boost in energy)
- Vegetables - 3-5+ portions per day.
For more information, you should speak to a dietitian or GP who can tailor a weight loss plan for you.
Exercise
Once you have started to fuel your body for your current lifestyle, it is then recommended to adding more movement and exercise to your day. Movement is a great way of boosting health and mood. Having just thirty minutes of physical activity a day can drastically increase weight loss and your wellbeing.
You may want to talk to a personal trainer for instruction and safety while your body adjusts to the change in daily exercise.
Wellbeing
Throughout your journey you will experience changes to your moods, behaviours, and emotions. It is important to remind yourself that it is perfectly normal to experience these feelings and be forgiving of yourself if you don’t meet your standards on any day. A helpful tool in maintaining your progress throughout your weight loss journey is to record your thoughts, feelings, and experiences in a journal; taking time to reflect on them each week. It can also be useful to start your day with small easy to complete goals, to help build your motivation to achieve the more difficult tasks later in the day.
Of course, everyone needs some help every now and then. Talking to a trained psychotherapist or psychologist can help you make and sustain changes throughout your journey.
Written by Qualified Experts
All of our medication and condition content is written by UK qualified pharmacists and doctors.
Reviewed: 17/03/2025
FAQ
General Information
What are weight loss injections like Mounjaro, Wegovy, and Ozempic?
GLP-1 treatments such as Wegovy and Ozempic (semaglutide) or Mounjaro (tirzepatide) mimic hormones that help control appetite and blood sugar by signalling fullness. Initially used for diabetes, they are now approved for weight loss at higher doses.
Who can use weight loss injections?
Ozempic is for type 2 diabetes, whereas Wegovy and Mounjaro are prescribed for obesity. They are typically recommended for individuals with a BMI of 30+ (or 27+ with related health issues), with UK guidelines usually suggesting them if your BMI is above 35 or 30+ with additional conditions.
Can I use Wegovy or Mounjaro without diabetes?
Yes. Wegovy and Mounjaro are approved for weight loss in people without diabetes who meet the required BMI criteria, while Ozempic primarily targets diabetes but can also aid weight loss.
Is a GLP-1 injection like insulin?
No. Weight loss injections are not insulin. They help your body release its own insulin and reduce appetite, working through a different mechanism than insulin, which directly lowers blood sugar.
Is there a pill form of GLP-1 treatments?
Only Rybelsus, an oral semaglutide, is available – but solely for diabetes. Weight loss injections such as Ozempic, Wegovy, and Mounjaro are available by injection only.
Effectiveness & Results
How effective are GLP-1 injections for weight loss?
Very effective. Mounjaro can achieve around 20% weight loss, Wegovy about 15%, and Ozempic typically 5–10%. Results are optimised when combined with diet and exercise.
How quickly do weight loss injections work?
Weight loss is gradual. Initial appetite changes may occur within weeks, but significant weight loss typically appears between 3–6 months and continues over time.
Why am I not losing weight with my Weight Loss Pen?
Initial weight loss can be slow, especially at lower doses. Higher doses of Mounjaro and Wegovy tend to offer better results. Also, check your diet and lifestyle, and discuss any concerns with your doctor.
What if my GLP-1 injection isn’t effective enough?
Your doctor might adjust the dose, switch medications, or suggest additional lifestyle modifications. Patience is essential as slow, consistent weight loss is typical.
Do weight loss pens have benefits besides weight loss?
Yes. GLP-1 injections improve blood sugar control, reduce the risk of diabetes, and can positively affect blood pressure, cholesterol, and other metabolic factors.
Will I regain weight after stopping injections?
Typically, yes – appetite and metabolism tend to revert once treatment stops. Ongoing use or strict lifestyle changes are necessary to maintain weight loss.
Which is the most effective weight loss injection for weight loss?
Mounjaro typically offers the highest weight loss (20%+), followed by Wegovy (around 15%), with Ozempic at diabetes doses providing moderate weight loss.
Administration & Usage
How are GLP-1 medications administered?
They are administered as subcutaneous injections into the abdomen, thigh, or upper arm using easy-to-use pens.
Do weight loss injections hurt?
Typically, no. The needles are very fine and any discomfort is usually limited to a brief pinch or mild sting.
Where should I inject weight loss injections?
Inject into fatty tissue under the skin of your abdomen, thighs, or upper arm. Rotate injection sites weekly to minimise irritation.
What if I miss a dose?
Take the missed dose within 4–5 days. If more time has elapsed, skip the dose and resume your regular schedule. Never double the dose.
What if I take an overdose?
Contact your doctor immediately. Side effects such as increased nausea may occur temporarily, but serious complications are rare.
Alcohol and GLP-1 treatments?
Moderate alcohol consumption is generally acceptable; however, it can increase nausea and may affect blood sugar control, particularly for diabetics.
Special diet or exercise needed with weight loss injections?
There is no specific diet, but a healthy, balanced eating plan and regular exercise can enhance the results of your treatment.
How do I store weight loss pens?
Refrigerate the pens before use. Once in use, Ozempic can be stored for up to 56 days, Wegovy for 28 days, and Mounjaro for 21 days at room temperature.
Can I travel with injections?
Yes, you can travel with your injections. Keep them cool in your hand luggage using an insulated bag and cool packs, and adhere to the recommended storage timelines.
Can I switch Weight Loss Pen?
Switching should be done under your doctor’s supervision. Typically, you would stop one medication and start the other at its lowest dose.
Safety & Side Effects
Are GLP-1 treatments safe?
Generally, yes. Although mild stomach issues are common, serious risks such as pancreatitis or thyroid cancer are very rare.
What are common side effects of GLP-1 treatments?
Common side effects include nausea, stomach discomfort, diarrhoea, and constipation. These are usually temporary and tend to improve over time.
Do GLP-1 weight loss injections cause low blood sugar?
Low blood sugar is rare when used alone, but the risk increases if combined with insulin or sulfonylureas.
How do I manage nausea when taking weight loss injections?
To manage nausea, eat small, bland meals, stay well hydrated, try ginger or peppermint, and consult your doctor about adjusting your dose if necessary.
Will nausea fade over time?
Yes, nausea typically diminishes within a few weeks to months as your body adjusts to the treatment.
Can I use GLP-1 treatments with other diabetes medications?
Yes, GLP-1 treatments are commonly used alongside other diabetes medications; however, doses of insulin or sulfonylureas may need to be adjusted to avoid hypoglycaemia.
Product Comparison & Availability
What are the differences between injections?
Mounjaro: dual-hormone action with greater weight loss (20%+).
Wegovy: single-hormone, high-dose treatment for obesity (around 15% average weight loss).
Ozempic: primarily for diabetes at lower doses, offering moderate weight loss.
Wegovy: single-hormone, high-dose treatment for obesity (around 15% average weight loss).
Ozempic: primarily for diabetes at lower doses, offering moderate weight loss.
Are they available on the NHS?
Wegovy is available for obesity under NHS specialist criteria.
Ozempic is prescribed for diabetes only.
Mounjaro has been approved recently for both obesity and diabetes, with access initially limited to specialist clinics.
Ozempic is prescribed for diabetes only.
Mounjaro has been approved recently for both obesity and diabetes, with access initially limited to specialist clinics.
What do they cost privately?
Privately, Mounjaro costs around £139–£229 per month, with Wegovy and Ozempic priced similarly or slightly less. NHS availability remains restricted.
Can I buy online without a prescription?
No. Always purchase from reputable, registered online pharmacies that are registered with the GPHC, like Simple Online Pharmacy.
What alternatives can I consider and how do they compare?
Alternatives include lifestyle changes, older medications with limited effect, and bariatric surgery—which is highly effective but invasive. GLP-1 injections offer significant weight loss (15–20%) without the risks of surgery.
Weight Loss Injections Treatment Comparison
| Saxenda | Xenical | Orlistat | Mysimba | |
| Ingredient | Liraglutide | Orlistat 120mg | Orlistat 120mg | Naltrexone/Bupropion |
| Mechanism | Regulates appetite | Reduces fat absorption | Reduces fat absorption | Regulates appetite |
| Dose | Injected once daily | One three times daily with meals | One three times daily with meals | Gradually increased to 4 tablets daily |
