Frequently asked questions

Eli Lilly, the manufacturer of Mounjaro, has increased the price of all dose strengths in the UK to align with prices across mainland Europe.

We know changes like this can feel unexpected and can lead to frustration. But our priority is to help you continue your weight loss journey with minimal disruption and find the treatment that best supports your health goals and fits your lifestyle.

Yes, under clinical guidance, switching weight loss medication is possible and not uncommon. With the recent price increase for Mounjaro, Wegovy has become a more cost-effective option per pen for weight loss and obesity management with prices starting from £99.99 a month.

Switching medications is a normal and common occurrence — it’s something medical professionals do regularly for conditions like high blood pressure or high cholesterol, whether it’s to reduce side effects or lower costs. We’ll work with you to find the treatment that’s right for your needs, budget and goals.

Mounjaro currently shows greater average weight loss in clinical trials, and as of July 2025, it remains the most effective medication available for weight management.

That said, Wegovy is still highly effective and delivers meaningful, lasting results. At the current maximum dose (2.4 mg), studies show people lose around 15% of their body weight on average over 68 weeks — with 10.3% loss at 6 months. This is far more than many achieve through lifestyle changes or older medications alone.

Wegovy also offers other benefits, including support for heart health, no impact on oral contraceptive effectiveness, and a lower cost than Mounjaro.

Wegovy and Mounjaro work in similar ways, so they can cause similar side effects. If you’ve been tolerating Mounjaro well, you’re less likely to experience new or increased side effects when switching to an equivalent Wegovy dose.

The most common side effects include nausea, vomiting, diarrhoea, constipation, and stomach pain. Wegovy may also cause fatigue or headaches in some people. These symptoms are often mild and temporary, and can sometimes be linked to dehydration or not eating enough nutrient-rich foods.

Our clinical team will create a personalised transition plan to help you move to Wegovy with equivalent efficacy and minimal risk of side effects.

If you have questions or want tips on managing side effects, visit our Weight Loss Health Guide.

At MedExpress, achieving a healthy weight is just the beginning of your weight loss journey. Maintaining your success is equally important.

We understand you might feel anxious at the thought of stopping weight loss medications once you reach a healthy BMI. The good news is that reaching your goal isn’t the end of your journey, it’s the beginning of maintaining your progress.

That’s why we continue to support you, even after you've achieved your goals. Rather than stopping medication automatically, our prescribers can continue to provide your weight loss medication for as long as you need to prevent weight regain.

We conduct regular check-ins to monitor your progress, adjust your treatment if necessary, and address any concerns you may have. This means you can feel confident in maintaining the results you have worked hard to achieve.

Injectable weight loss treatments like Wegovy® or Mounjaro® can sometimes be used after bariatric or gastric surgery, but it depends on your individual circumstances and will not be suitable for everyone. A key factor is timing: we typically require at least 12 months to have passed since your surgery before prescribing weight loss treatment. Other important considerations include the type of surgery you’ve had, your current health, and any ongoing symptoms.
When you complete your online consultation, our clinicians will review your full medical history to determine whether treatment is safe and appropriate for you.
If we have any concerns, we’ll let you know and guide you towards the safest next step. Your safety and wellbeing always comes first.

Limit alcohol while on GLP-1s, as it can worsen side effects like nausea and vomiting. We recommend limiting your intake to 1-2 alcoholic drinks each week.

You can still enjoy caffeine while using GLP-1s. But it’s worth noting that some people find caffeine can worsen side effects like nausea, acid reflux, or dehydration, especially early on. If you notice this, try cutting back to 1–2 coffees per day and see if it helps. Otherwise, there’s no need to avoid caffeine altogether.

Yes, you can take antibiotics while on GLP-1 weight loss treatments. However, they may increase gastrointestinal side effects such as nausea and diarrhoea. This is because both GLP-1s and antibiotics can affect the digestive system in similar ways, and taking them together may make these symptoms more noticeable.

No. We will not be able to prescribe weight loss treatment if you are taking alternative weight loss medication.

No. Do not take Wegovy (semaglutide) while pregnant. If you are planning to become pregnant, discontinue Wegovy at least two months in advance.

No. Do not take Mounjaro (tirzepatide) while pregnant. If you are planning to become pregnant, discontinue Mounjaro at least one month in advance.

Women of childbearing potential should use contraception while taking Wegovy.

Wegovy does not affect the effectiveness of the oral contraceptive pill. This means you can use birth control methods like the oral contraceptive pill, an IUD, an implant or a barrier method like condoms to avoid unplanned pregnancy.

If you experience severe diarrhoea that lasts for over 24 hours, or vomiting within three hours of taking your oral contraceptive pill, you may need a repeat dose of your oral contraceptive pill. Contact your GP or call 111 for medical advice if this occurs.

If you experience persistent vomiting or diarrhoea, consider using a non-oral contraception method. Contact your GP to discuss your options.

Women of childbearing ages should use contraception while taking Mounjaro.

Mounjaro impacts how your body absorbs the pill because it slows down digestion. This means you must use a non-oral birth control method like an IUD or implant or add a barrier method like condoms to avoid unplanned pregnancy.

MedExpress does not recommend the use of semaglutide when breastfeeding.

No, we advise patients to not use Mounjaro while breastfeeding. It is not yet known whether Mounjaro passes into breast milk, so the risk to a breast fed baby can’t be ruled out.

GLP-1 medications are safe to take long-term, and many people choose to stay on them to maintain their results. However, some may be able to taper off over time with the right lifestyle changes and support.

Strength training is especially important while taking GLP-1s to help prevent muscle loss during weight loss. Aim for 2–3 sessions per week, focusing on major muscle groups. Examples of strength training are lifting weights, working with resistance bands or yoga. Including these in your routine is a good way to maintain muscle mass while losing fat.

Health guidelines also recommend that adults do at least 150 minutes of moderate intensity activity a week or 75 minutes of vigorous intensity activity a week, but it is important to work up to this to avoid injury and prevent excess fatigue.

Examples of moderate intensity activities include: taking the dog for a walk, riding a bike to run errands, dancing, hiking and playing tennis.

Examples of vigorous activities include: running, swimming, riding a bike fast or on hills, walking up the stairs, skipping and aerobics.

We understand that starting or getting back into exercise can be challenging, especially if it has been a while. It’s important to choose an activity that you enjoy - when you enjoy it, you’re more likely to stick with it.

Eating enough protein is key to maintaining muscle mass while losing weight with GLP-1s. While all foods contain some protein, we recommend focusing on those high in protein and low in fat, known as lean proteins.

Try to include a source of lean protein at every meal. Examples include:

• Chicken breast
• Lean beef
• Pork tenderloin
• Tuna
• Salmon
• White fish
• Seafood
• Eggs
• Cottage cheese
• Greek yoghurt
• Protein powder
• Tofu
• Lentils
• Beans

We also recommend eating a diet rich in whole foods, which include lean proteins, healthy fats, and complex carbohydrates. This can help stabilise blood sugar levels and enhance feelings of fullness provided by your medication, making it easier to manage your appetite and achieve your health goals.

When starting with lower doses of Mounjaro and Wegovy, you may still experience feelings of hunger. These treatments are initiated at a low dose to minimise side effects and allow your body to adjust to the medication. As your dosage increases, you should notice a more significant reduction in hunger.

In clinical trials, patients taking semaglutide (the active ingredient in Wegovy) experienced weight loss of 14.9% in 68 weeks.

In clinical trials, patients taking tirzepatide (the active ingredient in Mounjaro) experienced weight loss of 20.9% after 72 weeks of treatment.

Some people experience rapid weight loss in a short period of time on their treatment. This is relatively normal, and if you aren't experiencing side effects, it simply means your body is responding well to your medication.

If you don’t feel you’re getting the results you want from your medication, our experts recommend continuing for at least 6 months, as results vary and your body needs to adjust. A weight loss of at least 5% after 6 months is generally expected and serves as a benchmark for our clinical team to continue prescribing treatment. If you're concerned, our clinical team can help with guidance and adjustments.

There is some evidence that suggests that you should stop taking weight loss medications a few weeks before surgery. If you’re planning to have surgery requiring a general anesthetic, please discuss the fact that you’re taking GLP-1 medication with the anaesthetist and inform the MedExpress clinical team.

Yes. To travel with your medication just keep it in its original packaging with the dispensing label visible. Carry it in your hand luggage in case of lost baggage, and store it in an insulated bag with cool packs if needed. If bringing needles, keep them sealed with a clear label. We recommend that you always check specific airline policies in advance.

Some people taking GLP-1 medications, such as semaglutide (Wegovy) or tirzepatide (Mounjaro), may notice changes in their vaginal bleeding. This can happen more often if they are also using hormone replacement therapy (HRT). Although this is increasingly observed, official guidance is still limited.

These changes might happen because GLP-1 medications slow down digestion. This can affect how your body absorbs hormone treatments — especially HRT taken as tablets, particularly oral progestogens. There don’t appear to be the same issues with hormone patches or intrauterine devices (like the Mirena coil). Weight loss and other body changes may also play a role.

This kind of bleeding is usually not serious, but it’s important to tell your doctor if you experience new, heavy or ongoing bleeding. They can check for other causes and may suggest adjusting your HRT or carrying out further tests if needed.