If you’ve been on the internet at any point over the past few years, you’ve probably heard of Ozempic. While it’s a medicine that’s licensed for type 2 diabetes, Ozempic is often used off-label for weight loss. And once people learned what sort of results it could drive, demand surged.
But there’s also other medicines out there that are specifically licensed for weight loss, like Mounjaro, Wegovy, and Saxenda, that work very well. For example, people taking Mounjaro might lose up to 22.5% of their initial weight.
With so many people talking about weight loss medication , it can be confusing to understand what’s available—and what might be best for you. For example, it’s not always obvious how you’re meant to get these medicines in the first place. Can you just go to your GP and ask for it or do you need a private prescription?
We hear you, it’s a lot to get your head around. Not to worry—we’ve explained everything you need to know.
What are weight loss injections?
They’re medicines that help you lose weight by making you feel full. And they do that by acting like certain hormones that are released naturally when you eat.
Namely: they slow down digestion (which keeps your appetite at bay), tell the brain you’re full, and stimulate the release of insulin when you eat (this also signals to the brain that you’ve had enough).
Saxenda, Wegovy , and Mounjaro all bring on these effects by acting like the hormone GLP-1. But Mounjaro behaves like another hormone as well: GIP. Because it brings on the effects of two hormones rather than one, Mounjaro is considered more potent.
Weight loss injections available in the UK
You might have noticed that we didn’t mention Ozempic in the above section. That’s because it’s not licensed for weight loss.
But it’s actually the same drug as Wegovy: both use the active ingredient semaglutide. Wegovy and Ozempic are brand names—when semaglutide is used for weight loss in people without type 2 diabetes, the medicine is called Wegovy.
Okay, so what injections are available for weight loss, then?
Mounjaro
Mounjaro weight loss pens have only just been approved by the UK’s National Institute for Health and Care Excellence (NICE) for use on the NHS. So they should be available on the NHS in the near future. Until then, you can get Mounjaro via private prescription.
Wegovy
On the other hand, Wegovy injections are available on the NHS. But you need to be referred to a specialist weight management service first, and there are often long waiting lists. Or you could get Wegovy from private providers.
Saxenda
You can get Saxenda on the NHS, too—but, again, you’ll have to be referred to a weight management service. Saxenda is available via private prescription as well.
How do UK weight loss injections compare?
Now that you know what’s available, your next question might be: what is the best injection for weight loss?
Well, everyone is different, so there’s no one-size-fits-all approach. You might find that Wegovy side effects don’t agree with you, for example, or that you prefer to use medicines that are taken weekly rather than daily.
To help you decide, here’s an overview of how UK weight loss injections stack up against each other. FYI: all three are self-injector pens you can do at home.
Mounjaro vs Wegovy vs Saxenda
Mounjaro
- Active ingredient: Tirzepatide
- Mode of action: Acts like GLP-1 and GIP
- How often do you take it? Weekly
- Dosage: Increases every four weeks, from 2.5mg to 5mg, 7.5mg, 10mg, 12.5mg, to 15mg
- Maintenance dose: Usually 5mg, 10mg, or 15mg
- Results: Average weight loss is 22.5% of starting weight in 72 weeks
- How common are side effects? Can affect over one in ten, usually mild and clear on their own
- Most common side effects: Nausea, vomiting, diarrhoea, stomach pain, constipation
- How long should I take it for? For best results, at least a year. But your provider will advise
- Available on the NHS? Approved and will be available soon, though a referral might be required (at least initially)
- Prescription-only? Yes
Wegovy
- Active ingredient: Semaglutide
- Mode of action: Acts like GLP-1
- How often do you take it? Weekly
- Dosage: Increases every four weeks, from 0.25mg to 0.5mg, 1mg, 1.7mg to 2.4mg
- Maintenance dose: Usually 2.4mg
- Results: Average weight loss is 14.9% of starting weight after a year
- How common are side effects? Can affect over one in ten, usually mild and clear on their own
- Most common side effects: Nausea, vomiting, constipation, diarrhoea, headache, stomach pain, tiredness
- How long should I take it for? For best results, at least a year. But your provider will advise
- Available on the NHS? Yes, with referral to weight management services
Saxenda
- Active ingredient: Liraglutide
- Mode of action: Acts like GLP-1
- How often do you take it? Daily
- Dosage: Increases every week from 0.6mg to 1.2mg, 1.8mg, 2.4mg to 3mg
- Maintenance dose: 3mg
- Results: Average weight loss is 7.4% of starting weight after a year
- How common are side effects? Can affect over one in ten, usually mild and clear on their own
- Most common side effects: Nausea, vomiting, constipation, diarrhoea, headache
- How long should I take it for? For best results, at least a year. But your provider will advise
- Available on the NHS? Yes, with referral to weight management services
- Prescription-only? Yes
*The maintenance dose is the strength of the medicine where it has the effect we want it to without causing difficult side effects. It’s the dose you stay on while taking the medicine. For example, if you were getting Mounjaro side effects from a 12.5mg dose, your provider might suggest dropping down to 10mg. It’s totally fine to be on a lower strength of these medicines, they will still work!
Who is eligible for weight loss injections?
Each of these weight loss injections has similar eligibility criteria. And ultimately, your provider will decide which is best suited to you. They’ll consider your medical history, starting weight, and general health when making the call.
Saxenda, Wegovy, and Mounjaro are all licensed for use in people with a BMI of 30 or more, or at least 27 if they also have another health problem related to their weight.
Though if you’re pregnant or breastfeeding, you shouldn’t take any of these medicines.
How to integrate medications into a weight loss plan?
Weight loss injections work very well, but they aren’t a shortcut to reaching your health goals.
They’re meant to be used alongside a healthy diet and regular exercise for at least a year. Otherwise, they might not work as well. The idea is that you lose weight gradually and sustainably by making changes that last.
You’ll introduce weight loss injections by starting on the lowest strength and progressively increasing your dose. This way, your body can get used to the medicine and handle higher strengths down the line.
For instance, in the Wegovy dosing schedule , you start at 0.25mg and then move up every four weeks, provided you’re tolerating the medicine okay. Mounjaro dosing follows the same pattern: you start at 2.5mg and then increase every four weeks. With Saxenda, the dose goes up every week.
How to access weight loss injections in the UK
You can try to get Wegovy or Saxenda on the NHS, but again, you’ll need a referral to weight management services and there can be long wait lists. Mounjaro isn’t available on the NHS just yet.
The other option is to get a private prescription. But watch out: don’t buy them from just anyone. Online services selling medication should be registered as a pharmacy—and this should be stated clearly on their website. If you scroll down to the footer of this page, you’ll see our registration details.
And if you’re using an online doctor service, make sure they’re registered with the Care Quality Commission (CQC) and General Medical Council (GMC).
This is super important, because if you buy weight loss medicine from services that aren’t registered, there’s no guarantee their products are genuine, safe, or in-date.
FAQs
Are weight loss injections safe?
Yes, they’re generally considered safe for most people. Though you shouldn’t take weight loss injections if you’re pregnant or breastfeeding. Tell your provider about your medical history.
How much weight can I lose with weight loss injections?
Potentially quite a bit. In scientific research, average weight loss was 7.4% after taking Saxenda for a year. And people taking Wegovy and Mounjaro might lose around 15-22.5% respectively.
What happens when you stop taking weight loss injections?
It takes a little while for medicine to clear from your system, so you won’t notice a change right away. For instance, when you stop taking mounjaro or wegovy it takes about one week for half a dose to be flushed out, so its effects will start to dwindle after that. Saxenda will clear a lot quicker: it takes just 13 hours for half a dose to leave your system.
Should you buy weight loss injections online?
Only if you’re getting it from a registered pharmacy or an online doctor service that’s registered with the Care Quality Commission (CQC) and General Medical Council (GMC). Be careful out there, not all the medicines sold online are safe.
Can you drink alcohol on weight loss injections?
There’s no rule against it. But we’d suggest proceeding with caution here , because alcoholic drinks tend to be high in calories. And after a few, you might find that you’re craving comfort foods that are high in fat and sugar. Both of these factors can work against your health goals.
How old do you need to be to buy weight loss injections?
You need to be an adult (i.e. at least 18 years old) to buy weight loss injections.
Your next step
If you’ve tried to lose weight by making healthy lifestyle changes but didn’t get the results you hoped for—we see you. But please don’t let that discourage you.
Weight loss medication can be a great option here. We know you can reach your health goals—and our weight loss programme can help you get there, via weekly medication and one-to-one support from our coaches. Fill out this form to see if you’re eligible. It’ll take just a few minutes.
¹Arrone, Louis J, et al. “Continued Treatment with Tirzepatide for Maintenance of Weight Reduction in Adults with Obesity.” JAMA
, vol. 331, no. 1, 2023:38-48. https://pmc.ncbi.nlm.nih.gov/articles/PMC10714284.
²“Mounjaro: Information for the Patient.” Electronic Medicines Compendium. https://www.medicines.org.uk/emc/files/pil.15481.pdf Accessed 31 Jan. 2025.
³Mehta, A, et al. “Liraglutide for Weight Management: A Critical Review of the Evidence.” Obesity, Science & Practice, vol. 3, issue 1, 2016:3-14. https://onlinelibrary.wiley.com/doi/10.1002/osp4.84.
⁴“Obesity: Treatment.” NHS, 2023 https://www.nhs.uk/conditions/obesity/treatment/ Accessed 31 Jan. 2025.
⁵“Saxenda: Full prescribing information.” Food and Drug Administration. https://www.accessdata.fda.gov/drugsatfda_docs/label/2023/206321s016lbl.pdf Accessed 31 Jan. 2025.
⁶“Saxenda: information for the patient.” Electronic Medicines Compendium. https://www.medicines.org.uk/emc/files/pil.2313.pdf Accessed 31 Jan. 2025.
⁷“Tirzepatide for Managing Overweight and Obesity.” National Institute for Health and Care Excellence. 2024 https://www.nice.org.uk/guidance/ta1026/chapter/1-Recommendations Accessed 31 Jan. 2025.
⁸“Wegovy: information for the patient.” Electronic Medicines Compendium. https://www.medicines.org.uk/emc/files/pil.13800.pdf Accessed 31 Jan. 2025.
⁹Wilding, John P.H., et al. “Once-weekly Semaglutide in Adults with Overweight or Obesity.” The New England Journal of Medicine, vol. 384, no. 11, 2021:989-1002 https://www.nejm.org/doi/full/10.1056/NEJMoa2032183.
