Is medicated weight loss safe?

Reviewed by our clinical team

What is medicated weight loss? 

Medicated weight loss refers to treatments prescribed to lose weight. They can help achieve a sustained and healthy weight alongside a healthy diet and exercise. In the UK, there are two main weight loss treatments, and another treatment which is due to be available this year. These weight loss treatments are: 

• Orlistat - also available under the brand name Xenical
• Mounjaro® (tirzepatide)
• Saxenda® (liraglutide) 
• Wegovy® (semaglutide) 

You can read about the different types of treatments and how they work in a guide to medicated weight loss, and the table below provides a brief summary of medicated weight loss treatments, their active ingredients, how they work, and their effectiveness.

*% of people losing more than 5% of body weight 

Who can take weight loss drugs? 

Not everyone can take weight loss medication. In fact, safe prescribers put a strict selection criterion in place to ensure patient safety. This is because medicated weight loss can't be prescribed to patients with certain conditions, medical histories, and if on certain medications. 

Weight loss treatments should only be prescribed to people who are obese – adults are generally considered obese if they have a BMI of 30 or more. Some medicated weight loss treatments can also be prescribed to people with a BMI of 27 or more (e.g., Mounjaro®/Saxenda®/Wegovy®) or 28 or more (e.g., Orlistat) if they have an associated condition (or co-morbidity), for example, high blood pressure.  

It's very important that patient safety is at the forefront of any consultation. Because of this, providing your healthcare provider with the correct information as you move through a consultation, and throughout your weight loss journey, is vital.

Weight loss drugs and eating disorders

Some people who diet or take weight loss drugs can develop an eating disorder. An eating disorder is a mental health condition which is influenced by your relationship with food and your body.

People with an eating disorder use different eating behaviours to cope with difficult emotions or situations such as compulsively exercising or restricting food. They may become obsessed with food, weight loss and their appearance.

If you or someone you know is struggling with an eating disorder you can speak to your GP or charities such as Beat Eating Disorders who can support.   

Are medicated weight loss pills and injections safe? 

Orlistat/Xenical

This treatment, taken as a pill up to three times a day, has been proven to be safe and effective during clinical trials. Orlistat does have some side effects, such as pain and discomfort in the stomach (you can read more about the side effects in the patient information leaflet), and can interact with other medicines, making them less effective. Because of this, during a consultation, clinicians need to know about any prescribed, recreational and over-the-counter drugs being taken. 

Orlistat isn't suitable if you are pregnant or breastfeeding.  

Wegovy®

Wegovy® has been approved by NICE  (National Institute for Health and Care Excellence) for people living with obesity. A 68-week study shows that around 85% of people lost more than 5% of their body weight.  

Wegovy® won't be suitable if: 

• You're over 75 
• You're pregnant or breastfeeding 
• You have liver, kidney or heart failure 
• You have an eating disorder 
• You have pancreatitis 
• You're taking insulin 

Mounjaro®

Mounjaro ® is safe for adults with a BMI of 30 or above or adults with a BMI of 27 or above with weight related health problems. You won’t be able to use Mounjaro® if you don’t meet these criteria. Our clinicians will make sure that it’s safe for you to take. We’ll also make sure you’re tolerating each titration well as you move through the doses. In clinical trials 96% of adults lost at least 5% of their starting body weight on the 15mg dose.  

Saxenda®

Saxenda® is available on the NHS and privately as a safe weight loss treatment. Very common side effects of the weight loss injection include feeling sick and diarrhoea. You can read more about the side effects of Saxenda® in the patient information leaflet. This leaflet also includes warnings and precautions, such as: 

• The use of Saxenda® isn't recommended if you have heart failure 
• There's little experience with this medicine in patients over 75 or patients with liver problems 
• Saxenda® shouldn't be taken as a replacement for insulin  
• Your doctor should be informed if you’ve had a disease of the pancreas during your medicated weight loss consultation 
• If you lose a lot of weight, you're at risk of gallstones and an inflamed gall bladder. You should inform your clinician immediately if you have severe pain in your upper abdomen when taking Saxenda®

Saxenda® shouldn't be taken if you are pregnant or breastfeeding. 

Medicated weight loss controversy  

Controversy around medicated weight loss exists because it's sometimes dangerously branded as a 'quick fix'. There have also been some worrying cases where people have accessed treatments through unregulated service, which isn't  safe at all. 

Medicated weight loss shouldn't be offered without a consultation, and it's important to stress that is should be used alongside positive lifestyle changes and a healthy diet. 

During a medicated weight loss journey, to stay safe, you should report any concerning side effects to your doctor. Keep in regular contact and ask questions you might have along the way.  

LloydsPharmacy Online Doctor’s medicated weight loss clinic  

If you need help losing weight, if suitable for you, we can safely prescribe treatment such as weight loss pills and weight loss injections to support your weight management plan. We also have plenty of weight loss resources in our healthy lifestyle hub.  

References

https://www.medicines.org.uk/emc/product/13801/smpc
https://www.medicines.org.uk/emc/product/2313/smpc#gref
https://www.ema.europa.eu/en/documents/scientific-discussion/xenical-epar-scientific-discussion_en.pdf
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3125014/
https://www.medicines.org.uk/emc/files/pil.2592.pdf
https://www.medicines.org.uk/emc/files/pil.2313.pdf
https://www.nice.org.uk/news/article/nice-recommends-new-drug-for-people-living-with-obesity