What is Wegovy? Uses, how it works and side effects

Wegovy is a prescription-only medicine (aka POM) that contains semaglutide. It’s part of a group of medicines called GLP-1 receptor agonists - the same family as Ozempic.

Unlike Ozempic, which is licensed for type 2 diabetes only, Wegovy is licensed for weight management. NICE has also recommended semaglutide to reduce the risk of heart attacks and strokes in people who are overweight or obese with existing cardiovascular disease.

Under current National Institute for Health and Care Excellence (NICE) guidance, Wegovy can be prescribed if:

• Your BMI is 35 or above and you have at least one weight-related condition (for example, high blood pressure, type 2 diabetes or sleep apnoea)

• Your BMI is 30–34.9 and you’ve been referred to a specialist weight management service with weight-related health problems

• You’re from an ethnic group at higher risk of obesity-related illness (such as South Asian, Chinese, Middle Eastern, Black African or African-Caribbean backgrounds) — in these cases, eligibility may start at a BMI of 27.5

Access is via specialist NHS clinics or, sometimes, through private providers following the same clinical rules. A full medical assessment is always needed first.

While many people do lose weight with Wegovy, it’s not a magic jab. It has to be used alongside lifestyle changes like a healthier diet and regular activity, and it comes with possible side effects that need to be considered.

Plus, given the recent price hikes in Mounjaro, many Mumsnet users are switching or planning to switch to Wegovy for their weight loss journey.

So, we spoke to Dr Daniel Atkinson, clinical lead at Treated, to help explain what you need to know about the medication.

In this guide you’ll find

• How Wegovy works

• Who is prescribed Wegovy?

• How it’s taken

• Side effects and safety information

• What to expect from treatment

• What Mumsnet users say

• Who to talk to about it

• Useful links for more information

What is Wegovy and how does it work?

Like Ozempic and Mounjaro, Wegovy is a weekly injection. It mimics a natural hormone called GLP-1 (glucagon-like peptide-1).

As Dr Daniel explains: 

“Semaglutide is the active ingredient in Wegovy. It’s a GLP-1 agonist, which mimics the effect of the naturally made glucagon-like-peptide-1 hormone. In short, it helps regulate your blood sugar and reduce your appetite.

“Unlike other GLP-1s that also treat diabetes, Wegovy is specifically licensed as a weight loss treatment. It contains a higher maximum dose than Ozempic, which also contains semaglutide.” 

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When we eat, our guts release GLP-1, which plays several roles in helping our bodies process food and regulate appetite. It:

• Signals to our brain that we’re full (which helps to reduce hunger and ‘food noise’)

• Slows the rate at which our stomachs empty, so we stay fuller for longer

• Helps our pancreas release insulin when blood sugar rises, and reduces glucose output from the liver

“By mimicking the effects of GLP-1, patients using Wegovy will have a better control of their appetite and want to eat less”, Dr Daniel adds. “This can help them achieve the calorie deficit needed for weight loss.”

It isn’t insulin, and it doesn’t work the same way as diabetes medicines, even though it contains the same ingredient as Ozempic.

Who might be prescribed Wegovy?

Wegovy is for people with obesity, or those who are overweight with weight-related health conditions. It’s not for cosmetic use.

Dr Daniel explains: “Wegovy can be prescribed through the NHS by a specialist weight management service if your BMI is 35 or more and you also have a weight-related health condition like hypertension, and if you’ve tried losing weight through other approaches that haven’t worked. 

“If your BMI is between 30-34.9, you might still be able to get Wegovy through the NHS if you've been referred to a weight management specialist (and have a weight-related condition).”

In short, NICE guidance currently recommends Wegovy for:

• Adults with a BMI over 35 and at least one comorbidity

• Adults with a BMI 30–34.9 plus weight-related problems, if under specialist care

• Adults from higher-risk ethnic groups, sometimes from a BMI of 27.5

In Scotland, doctors follow guidance from the Scottish Medicines Consortium (SMC), which may differ slightly.

“Sometimes, Wegovy is prescribed ‘off-label’ for those with a BMI lower than 27, but off-label prescribing is only usually done in exceptional cases where other approaches haven’t been successful,” shares Dr Daniel. 

Side effects like reduced 'food noise' and less of an appetite are common

Getting Wegovy through the NHS

If you think you might meet the criteria, your GP can refer you to a specialist NHS weight management service. From there:

• They’ll carry out a full assessment of your health, weight history and lifestyle

• If suitable, Wegovy may be prescribed as part of a wider plan with diet, exercise and behavioural support

• On the NHS, treatment is usually limited to two years under specialist supervision, with regular reviews

Getting Wegovy through a private healthcare provider

Some private healthcare providers also prescribe Wegovy - but they must follow the same clinical safety standards as NHS services. That means:

• You’ll need a full health check including BMI, history and screening for risk factors

• Clinics must be properly regulated (for example, by the CQC in England)

• They must be regulated by the Care Quality Commission (CQC) in England, or equivalent bodies elsewhere in the UK.

No matter what route you take, a thorough health assessment is important. As Dr Daniel explains: “Consulting with patients and checking their medical history gives a clear idea of whether a medication is suitable for them.

“If they’re trying to use it for reasons beyond losing weight and improving their health, it’s usually apparent and their treatment will be declined.”

Afterall, Wegovy should be used as part of a wider weight loss plan, Dr Daniel confirms. One that “involves lifestyle changes such as healthier eating and increased activity. 

“It will work more effectively when used this way, and the changes you implement should last once your treatment has finished.”

Do not get Wegovy from unregulated sources

! Be cautious, though: Don’t buy Wegovy online without a consultation. It’s unsafe and illegal in the UK.

Dr Daniel shares: “Obtaining prescription-strength medications from unregulated sources can be dangerous. You won’t have any guarantees of legitimacy and safety when it comes to your health. Instead, look for accreditation from any sources you use. 

“In the UK, doctors should be registered with the General Medical Council (GMC), and pharmacy prescribers with the General Pharmaceutical Council (GHpC).”

Make sure you're purchasing your Wegovy from a registered pharmacy prescriber or doctor

How is Wegovy taken?

Wegovy comes in a pre-filled pen for weekly injections into the fatty tissue under the skin.

The injection is given subcutaneously (into the fatty tissue just under the skin) in three common sites:

• Stomach (avoiding a two-inch area around the belly button)

• Front of the thigh

• Upper arm (usually if someone else is giving the injection)

Your healthcare professional will show you how to use the pen, rotate injection sites and safely dispose of needles.

Dose and titration

To minimise side effects, you’ll usually start on a low dose and increase it gradually over several months until you reach the maintenance dose. 

Dr Daniel clarifies: “The titration dosage schedule for Wegovy means patients typically start on the lowest dose, then change pens once a month until they reach a maintenance dose. 

“But weight loss works at different speeds for everybody, so you might find a dose you want to stick with for longer than four weeks.”

Here’s an example schedule: 

1. 0.25 mg once a week for four weeks

2. 0.5 mg once a week for four weeks

3. 1.0 mg once a week for four weeks

4. 1.7 mg once a week for four weeks

5. 2.4 mg once a week (maintenance dose)

Your prescriber may pause or slow the dose increase if side effects are troublesome.

Missed doses

If you miss a dose and it’s within five days of your scheduled injection, you can take it as soon as you remember. 

If more than five days have passed, skip the missed dose and take your next one at the usual time.

🚩 Moving from Mounjaro to Wegovy?

If you're switching from Mounjaro to Wegovy, you'll need to work with your doctor to do it safely. These are two different weight loss medications that work in slightly different ways.

You can't just swap one for the other - you'll typically need to stop Mounjaro for a period of time before starting Wegovy. When you do start Wegovy, you'll begin with the lowest dose, not whatever dose you were taking with Mounjaro.

Both medications can cause side effects like nausea, and your body will need time to adjust to the new medication. Your doctor will monitor how you're doing and adjust the timing and dosing based on how you respond.

The key thing is not to make this switch on your own - your doctor needs to guide the process to make sure it's safe and effective for you.

Wegovy side effects and safety considerations

Like all medicines, Wegovy can cause side effects, especially in the early weeks or after a dose increase.

Dr Daniel explains: “Common Wegovy side effects include nausea, diarrhea and vomiting. They should ease as your body gets used to the medication.”

In summary, common side effects include:

• Nausea

• Vomiting

• Diarrhoea

• Constipation

• Abdominal pain

• Indigestion or reflux

• Reduced appetite

• Fatigue

These usually ease as your body adjusts. Eating smaller, lighter meals and avoiding rich foods can help.

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Less common but more serious side effects may include:

• Pancreatitis (severe stomach pain, often with vomiting)

• Gallbladder issues (like gallstones)

• Low blood sugar (if you’re also on other diabetes medicines)

• Allergic reactions (rash, swelling, difficulty breathing)

• Worsening diabetic retinopathy (in people with type 2 diabetes)

Seek immediate medical attention if you experience any severe or unusual symptoms.

Who shouldn’t take Wegovy?

Like all medication, Wegovy is not suitable for everyone and should not be used if you:

• Are pregnant, breastfeeding or planning to conceive soon

• Have a known allergy to semaglutide or any of the other ingredients

• Have certain severe gastrointestinal conditions (your prescriber will advise)

In the US, people with a personal/family history of medullary thyroid cancer or MEN2 are advised not to take semaglutide. In the UK, this isn’t listed as an official contraindication, but doctors may still avoid prescribing it in these cases.

Dr Daniel adds: “It might not be suitable for people with kidney or liver disease, but often the safety of medications for patients is judged case by case. 

“Wegovy isn’t safe for pregnant women as more research is needed about the risks it can cause to their baby’s health.”

Drug interactions

Because Wegovy slows down how quickly food leaves the stomach, it can affect how well some tablets are absorbed (like the contraceptive pill, anti-depressants or certain painkillers). Your prescriber will advise if this applies to you.

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What to expect from treatment

Wegovy is part of a long-term plan for weight management – it’s not a quick fix. Throughout treatment, you can expect to:

• Have regular check-ins with your healthcare team

• Monitor weight, waist circumference, blood pressure and other health indicators

• Continue dietary and physical activity changes alongside medication

• Potentially stop treatment if it’s not effective or side effects outweigh benefits

Medical check ups are important, as Dr Daniel stresses: “Follow-up aftercare is essential when someone is starting a weight loss treatment, to see if they’re happy with their dose, and if any side effects they get are manageable.

“Research into the long-term safety of taking Wegovy is ongoing”, he adds, “so for now treatment is limited to two years. 

“Once you’ve finished a course, you’ll hopefully continue to eat well and exercise regularly in order to remain at a healthy weight.

But remember - results vary: Some people see significant weight reduction, others more modest changes. NICE guidance suggests that if you haven’t lost at least 5% of your starting weight after six months at the full dose, it’s worth reviewing whether to continue.

Remember that results vary from person to person

What Mumsnet users say about Wegovy

Since the start of January, we’ve seen Mumsnet users consistently describe Wegovy as an effective aid for weight management and a tool for reducing persistent food noise.* Switching from other GLP-1 drugs (such as Mounjaro) for better results or pricing was also frequent.

“It really reduces my 'food noise' and I can genuinely reduce my food intake but I suffer with constipation loads and occasional weird burps!” lostinabook

“[...] This is the first time I have ever been freed from the compulsion to eat sugary foods. It started to creep back yesterday evening so I am hoping that this evening's jab will take it away again. It's like being unchained from a maniac.” tioabar

“Is anyone else surprised that this actually works? It's literally like someone turned my brain off - the bit of it that goes ooh, chocolate, ooh, biscuits, ooh, cake, anyway [...]” thornbury

“It's going ok for me. First day of no headaches so I managed to get out for a 5k walk with my husband which was nice. Appetite is definitely reducing, even if I feel hungry I'm getting full far quicker. Like a previous poster I am definitely feeling lighter even though I know after 5 days it's going to be very minimal. Let's see how the weekend goes!” TeaAndTapas

“I’ve just finished my first week of Wegovy. No choice, as Mounjaro is not an option because of other drugs I have to take. Very interested to see that most people are taking MJ. I have certainly not wanted to snack between meals and expect I have lost a small amount, but nothing drastic. Very pleased that I’ve had no side affects.” Difficultdora

“[...] I definitely feel fuller sooner which is quite fascinating (my portion sizes are tiny) and have less interest in food generally. Snacking isn’t entirely curbed - if it’s there, then I can still have it but it’s far far less of a craving or compulsion and feels more controllable [...]” DunnoMate

Who should you speak to about starting treatment?

“You should see your GP if you want to start using Wegovy”, shares Dr Daniel. “They can advise you about ways to lose weight, and check your eligibility for treatment. 

“If you decide to get Wegovy from an online pharmacy, they should be equally as thorough when it comes to checking your medical history and suitability.” 

In short, if you’re wondering whether Wegovy might be suitable for you:

• Start with your GP as they can check your BMI, review your health and refer you to a weight management service if needed

• If you’re already under the care of a specialist clinic, discuss whether semaglutide is an option in your treatment plan

• Always seek information from qualified healthcare professionals, not social media or unverified websites

Useful links for more information

• NHS: Obesity treatment

• The NHS Digital Weight Management Programme 

• NICE: Semaglutide for managing overweight and obesity

• MHRA Yellow Card Scheme – report suspected side effects

About the expert

• Dr Daniel Atkinson is the Clinical Lead at Treated.com, an online healthcare service company.

About the author

Our resident Leeds lass, Rebecca Roberts is a Senior Content Editor here at Mumsnet. On a daily basis, she commissions, writes and edits content designed to help parents navigate real life - from product reviews to practical features on everything from sex and relationships to fashion to skincare.

Rebecca - aka Beccy - brings unique personal insight to weight loss content here at Mumsnet, having undergone her own journey with medically supervised injections. Her firsthand experience with GLP-1 treatments provides authentic expertise that resonates with parents exploring similar options. 

Beyond her role as an editor, she can be found balancing life as a working mum of two toddlers and when she’s not at her desk, you’ll likely find her at a PTA meeting, in a nearby coffee shop, or walking her two dogs up and down country lanes.

*MumsGPT 1 January 2025 - 12 August 2025