Close medical management of weight loss drugs vital, says expert

Are some online pharmacies failing patients when prescribing GLP-1 drugs? Learn what one expert thinks.



To illustrate his point, Garvey pointed to the fact that different patients respond differently to GLP-1 drugs. 'There are individuals who are very responsive to low [GLP-1] doses who lose a lot of weight on submaximal doses and may lose too much weight on maximal doses', he said.

That's one reason SemaPen patients receive a smart body scale when they join our programme. This allows us to track patients' weight loss in the cloud – and adjust their dose or offer holistic advice if we notice rapid weight loss.

Under the online pharmacy model, which typically lacks this kind of close monitoring, patients may be unaware that they're losing weight too quickly. As a result, they may continue to increase their dose as per the standard dosing schedule – compounding the problem and potentially leading to adverse effects.

The problem of lesser-known side effects

In the world of medicine, there is no one-size-fits-all solution. Each patient must be treated as an individual – and healthcare professionals must be ready to adjust treatments based on real-world observations, not just clinical data.

Nowhere is this more apparent than in the case of lesser-known and unexpected side effects.

In his lecture, Professor Garvey noted several GLP-1 side effects that he and others had observed – but which may not have been apparent from the initial clinical trials.

For example, phase 3 trials of Wegovy and Mounjaro both noted nausea as the most common adverse event. In those trials, it affected 44% of Wegovy users and 31% of Mounjaro users.

However, Garvey pointed to a more recent analysis of GLP-1 patient data, which found that abdominal pain was the most reported adverse event – and by some measure. In this study, around 58% of semaglutide users reported experiencing stomach pain, while only 20.8% reported nausea.

'I was kind of surprised to see abdominal pain', Garvey said. 'I hadn't seen a lot of that.'

Garvey also warned of another potential side effect – an almost complete loss of appetite among those who experience rapid weight loss. This can lead to symptoms such as fatigue, weakness and cognitive clouding (brain fog).

As Medscape notes, 'the solution is to decrease the GLP-1 dose or discontinue it entirely'. But Garvey has encountered resistance from patients who don't want to stop treatment because they're 'so happy they're losing weight'.

'That's why it takes active management by a healthcare professional to recognise this', he said.

How is SemaPen different?

It's quite simple. SemaPen is not an online pharmacy.

We are a weight loss clinic that – through our association with Phoenix Health – has helped people with obesity lose weight for more than 20 years.

If two decades of experience have taught us anything, it's that patient well-being is paramount. That's why we never prescribe and run. When you join the SemaPen weight loss programme, you're doing just that – joining a medically managed, closely monitored programme designed by UK obesity experts.

It's all about making sure our patients have the support and resources they need to achieve their weight loss goals.

For you, this means getting a digital scale that records your weight in the cloud – and triggers a specialist review if you lose weight too quickly or too slowly. It means having access to nutritional and psychological support through the SemaPen app. And most importantly, it means knowing that real specialists are monitoring your progress – including watching for complications that may arise during your weight loss journey.

Want to learn more about how it works? Start by taking a look at our Mounjaro and Wegovy medication programmes – or complete our online consultation to find out if you're eligible today.

Sources

1. Wilding, J.P.H. et al. (2021) "Once-weekly semaglutide in adults with overweight or obesity" The New England Journal of Medicine, 384(11) https://doi.org/10.1056/NEJMoa2032183

2. Jastreboff, A.M. et al. (2022) "Tirzepatide Once Weekly for the Treatment of Obesity" The New England Journal of Medicine, 387(3) https://doi.org/10.1056/NEJMoa2206038

3. Punjwani, A. et al. (2023) "Weight reduction after bariatric surgery - Do results correlate with postoperative visit frequency?" Obesity Pillars, 8 https://doi.org/10.1016/j.obpill.2023.100093

4. Aldhaleei, W.A. et al. (2024) "Glucagon-like Peptide-1 Receptor Agonists Associated Gastrointestinal Adverse Events: A Cross-Sectional Analysis of the National Institutes of Health All of Us Cohort" Pharmaceuticals, 17(2) https://doi.org/10.3390/ph17020199

This article was reviewed and approved by Qutayba Almerie MD, MSc, FRCS on 14 July 2025.