Weight loss injections and tablets have changed what's possible for people living with obesity. They're not a quick fix or a replacement for eating well and moving more, but alongside those changes they can help people lose a significant amount of weight and keep it off. At MedsRus, a UK prescriber reviews your health, checks your weight independently and agrees a plan with you. Then we support you through each dose.
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How do weight loss injections work?
Most of the newer weight loss medicines are GLP-1 medicines. They copy a natural hormone your gut releases after you eat. It tells your brain you're full, and it slows down how quickly your stomach empties. The result is that you feel less hungry, get full sooner and think about food less.
Tirzepatide (Mounjaro) also acts on a second gut hormone, called GIP. The injections are given once a week with a pre-filled pen, usually into your tummy or thigh. It only takes a few seconds, and the needle is very fine.
Our guide to weight loss pens explains how to use them step by step.
Weight loss treatment options
| Tirzepatide injection (Mounjaro) | Semaglutide injection (Wegovy) | Semaglutide tablet (Wegovy pill) | Orforglipron tablet (Foundayo) | Orlistat (Xenical) | |
|---|---|---|---|---|---|
| How it's taken | Weekly injection | Weekly injection | Daily tablet | Daily tablet | Capsule with each main meal |
| How it works | Reduces appetite (two hormones) | Reduces appetite | Reduces appetite | Reduces appetite | Stops some fat from food being absorbed |
| Good to know | Dose goes up step by step every 4 weeks | Dose goes up step by step every 4 weeks | Take on an empty stomach with a sip of water, then wait before eating | Can be taken with or without food | Oily stools if you eat fatty food |
The Wegovy pill and Foundayo are newer: they were approved in the UK in 2026 for people who would rather not inject. Orlistat is an older medicine that works in a different way, and it may suit people who can't take GLP-1 medicines.
Tirzepatide vs semaglutide (Mounjaro vs Wegovy)
Both are weekly injections that reduce appetite. In studies, people on tirzepatide (Mounjaro) lost more weight on average than people on semaglutide (Wegovy), but everyone responds differently, and side effects and your medical history matter too. The prescriber will talk through which is suitable for you. For a deeper comparison, see Ozempic vs Mounjaro.
Who can have weight loss medication?
These medicines are licensed for adults with:
- a BMI of 30 or more; or
- a BMI of 27 to 30 plus a weight-related health condition, such as high blood pressure, type 2 diabetes, high cholesterol or sleep apnoea.
You can work out your BMI with the NHS BMI calculator.
UK rules mean we must check your weight and height independently, not just take your word for it. We'll ask for photos or a short video check, or details from your GP record.
Who shouldn't take them
They're not suitable if you're pregnant, trying to get pregnant or breastfeeding, or if you've had pancreatitis, certain thyroid cancers, or an eating disorder. They're also not meant for people who want to lose a small amount of weight for cosmetic reasons.
What to expect
Starting low and going slow
You start on a low dose and increase it gradually, usually every 4 weeks. This gives your body time to adjust and keeps side effects down. Our guide on how long weight loss medication takes to work covers a realistic timeline.
Side effects
The most common are tummy-related, and they're usually worst after starting or increasing a dose:
- feeling sick, and sometimes vomiting;
- diarrhoea or constipation;
- indigestion, burping or bloating;
- tiredness.
Eating smaller meals, slowing down and stopping when you feel full all help. Get urgent help if you have severe tummy pain that spreads to your back, as this can be a sign of pancreatitis.
Contraception and pregnancy
- If you take Mounjaro and the contraceptive pill, use condoms as well for 4 weeks after starting and after each dose increase, or switch to a non-pill method such as the coil or implant.
- Stop semaglutide at least 2 months, or tirzepatide at least 1 month, before trying for a baby.
Making the weight loss last
The medicine makes it easier to eat less, but what you eat still matters:
- prioritise protein and vegetables at every meal, to protect your muscle;
- drink plenty of water;
- build in some strength exercise each week;
- expect slower weeks. A weight loss plateau is normal.
If you stop treatment, some weight often comes back, especially if your habits haven't changed. Plan the end of treatment with your prescriber.
How it works with MedsRus
- Complete your consultation: your health, medicines and weight history.
- Verify your weight: we'll ask for proof of your weight and height.
- A UK prescriber reviews everything and, if treatment is suitable, agrees a plan and a starting dose with you.
- We deliver in discreet, temperature-controlled packaging, and check in before each dose increase.
Start your weight loss consultation →
Weight loss FAQs
How much weight can you lose with weight loss injections?
It varies a lot from person to person. In studies, many people lost 10% to 20% of their body weight over a year or more, alongside diet and activity changes, but some people lose less.
Are weight loss injections safe?
They're licensed medicines and are safe for most people when prescribed and monitored properly. Buying them without a prescription, or from unregulated sellers, is risky and illegal.
Can I get weight loss injections on the NHS?
In some cases, through specialist weight management services or your GP, with strict criteria and waiting lists. Many people choose a private prescription instead.
Do I have to inject myself?
Not necessarily. Daily tablet options are now available in the UK, although the injections are still the most widely used.
What happens when I stop?
Appetite usually returns, and some weight may come back. Keeping up the eating and activity habits you've built makes a big difference.
How much does weight loss treatment cost?
It depends on the medicine and the dose. For the injections, the price usually rises as the dose goes up, and each order is normally a month's supply. You'll see the price for each dose on the treatment page before you pay, and the prescriber only approves a dose that's right for you.
Can I switch from semaglutide (Wegovy) to tirzepatide (Mounjaro)?
Often, yes, but only under a prescriber's guidance. They'll look at your current dose, how you've got on and when you took your last dose, then advise a starting dose and when to begin. Never take both at the same time.
Why am I not losing weight?
It can take a few weeks at a higher dose to see steady results, and plateaus are normal. Read why am I not losing weight on a calorie deficit?
Further reading
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