Have a Digestive Condition? You May Still Be Eligible for GLP-1s

Posted on August 21, 2026 by Sally-Anne Turner

If you have ever looked into GLP-1 medications or followed a celebrity who takes them, you may have heard them talking about the side effects. Namely, the tummy issues.

It seems that with GLP-1 oral medications, the issues with the stomach are prevalent. So, this begs the question for many people wanting to try weight loss medication in the UK: if I have irritable bowel syndrome (IBS) and take loperamide, can I take GLP-1s? Or will this make it worse?

Our team at the Bodyline Clinic know all about the side effects of all GLP-1 medications. That's why we always advise a more clinical, medically backed approach to weight loss treatments. That way, you will have our excellent clinical team overseeing your journey with GLP-1s, and ensuring that any pre-existing conditions are checked before, during and even after treatment with us. Keeping you safe is crucial to a positive outcome and is why we offer those with complex care needs additional support when they come to us to lose weight.

So, what is the guidance on GLP-1s and gastrointestinal issues and does having something like Crohn's disease immediately exclude you from this weight loss option?

GLP-1s and GI Issues: What's Going On?

Before we look at the GI conditions which can prompt further oversight with GLP-1s, let's take a quick look at why these medications cause these side effects.

The most common GI side effects noted with GLP-1 medications (both injectable and oral) include:

• Nausea
• Vomiting
• Constipation, piles or haemorrhoids
• Loose stools/diarrhoea
• Gas (flatulence)
• Acid reflux

But why do they happen? And why may this pose an interesting dilemma for clinicians trying to treat people who may want to lose weight, but may have conditions like IBS?

Delayed Gastric Emptying

With GLP-1s, slowing down gastric emptying is one of the core things that the medication is designed to do, as it helps you feel full for longer. In the same way, it can cause people to feel sick, be sick or have stomach pain — not to mention difficulty with hard bowel movements.

Gut-Brain Interaction

The medical field is still learning about how the gut and the brain are connected. But with GLP-1 medications, the links have been highlighted and are thought to be a reason why people taking GLP-1s may develop stomach problems. GLP-1s interact with part of the brain stem, which is involved in appetite suppression and the vomiting reflex.

Faster Bowel Motility

On the flip side of the slower gastric emptying, some people who take oral or injectable GLP-1s may experience that when they eat food, it moves through their tummies faster. This can cause diarrhoea and loose bowel movements. Again, this is one of the things that GLP-1 medications are designed to do, but it can also lead to abdominal pain and a bit of heartburn.

Obesity and GI Problems: Is There a Link?

Another interesting side of this treatment option is the link between obesity and gastrointestinal issues. The findings are extremely surprising. For some of the most common GI issues, there is evidence that there is a link to also being diagnosed with obesity, or with having a higher BMI.

Starting with the weaker links in the data: if a person has chronic gastritis, coeliac disease, or irritable bowel syndrome (with mucus in stool), the evidence supporting obesity as a condition which exists alongside these GI problems is low. With coeliac disease, older research has pointed in the opposite direction — those who have it are often malnourished, due to absorption issues. However, a systematic review from 2024 (which explored 15,299 people in total) determined that 37% were either obese or overweight when they were diagnosed with coeliac disease. This is an interesting finding, but it does not mean there is a clear link.

A similar meta-study exploring IBS from 2024 (which involved 543,000 participants over 27 studies) found no clear link between IBS and the prevalence of excess weight.

On the other side of the coin, patients diagnosed with Gastrointestinal Reflux Disease (GERD), pancreatitis, or gallstones and gallbladder disease were found across meta-analyses and systematic reviews to have a higher incidence of obesity and being overweight:

• Those who had higher BMIs were at a 37% higher risk of developing GERD (Yiqing et al 2025).
• Higher BMIs were linked to a 63% increase in gallbladder disease (Aune 2015).
• A study from Premkumar noted a link between inflammatory markers, obesity and the development of pancreatitis.

Pancreatitis is interesting, as it is also noted to be a rare complication of GLP-1 medications, such as Mounjaro, the Wegovy injection and even oral weight loss medications.

What Does the Guidance Say?

The good news is that there is nuance with taking GLP-1s and the majority of common digestive conditions. In most cases, your clinical team should offer you additional oversight if you have a diagnosed gastrointestinal issue, based on MHRA Guidelines in the UK.

Contraindicated with GLP-1s

Starting at the top, if you have ever been diagnosed with severe gastroparesis, the MHRA has specified that this is contraindicated with GLP-1 treatments. This is more relevant in GLP-1s that include semaglutide, like Wegovy and Ozempic.

Additional Clinical Assessment

This is usually where our team at Bodyline comes in. There is the possibility, with additional personalised clinical assessment and oversight, that we can offer our patients with the following conditions additional clinical assessments. You should note that if you have comorbid conditions alongside those listed here, you may be unsuitable or will require additional assessments.

If you have moderate gastroparesis, previous pancreatitis, or gallstone and gallbladder disease, then we will need to establish a history. With moderate gastroparesis, we may need to exclude certain GLP-1s from treatment, like semaglutide. With previous pancreatitis, this is a rare side effect of taking GLP-1s, but it is not a blanket contraindication. In a similar vein, many GLP-1s are linked to gallstone disease, but with medical oversight and correct clinical guidance, the risks reduce drastically.

Monitor with GLP-1s

Now, onto the more common presentations of GI issues. If you have GERD or reflux, chronic gastritis, irritable bowel syndrome, coeliac disease, or a history of constipation, then our team will likely need to monitor you closely. Individual clinical circumstances matter, but baseline symptoms and severity may mean that we will need to conduct more clinical checks and assessments before medication starts. If you are taking anything, like IBS medication to help symptoms, let us know.

Incidentally, diet has an enormous role in how many people experience GLP-1s, more so those who have a history of a sensitive bowel. So, check out our piece on diet and GLP-1s for more information on that.

If, when taking GLP-1s, you notice any of the following, you need to seek emergency treatment and alert your prescriber:

• Severe, persistent abdominal pain — this could be pancreatitis or gallstones.
• Sudden, severe abdominal pain occurring with vomiting — again, it could be pancreatitis.
• Inability to keep fluids down due to extreme sickness and diarrhoea.
• Symptoms of severe dehydration (confusion, minimal production of urine).
• Loss of vision or deteriorating eyesight — this is more common when taking semaglutide.

Why Is Bodyline Different?

That was a lot to take in! However, if you do have a condition like coeliac disease but are also looking to lose weight, don't let that stop you from contacting our team. At the Bodyline Clinic, we are dedicated to helping those who may have been turned away from pharmacies to lose weight. We have a dedicated clinical team across seven clinics in the North West, who will meet you in person (or via digital platforms) to help you plan your weight loss with GLP-1s. Your plan is targeted to you, is medically supported, and will help to keep you safe.

So, if that sounds ideal, contact our team today for a free consultation.

FAQs

Why Do GLP-1s Cause Stomach Issues?

This is linked to delayed gastric emptying, which can cause nausea, and the gut-brain axis — GLP-1s impact part of the brain stem, which can lead to appetite suppression and vomiting. Lastly, some people experience diarrhoea, which is linked to faster stomach motility.

I Have IBS: Can I Use GLP-1s to Lose Weight?

You can, but you should alert your provider about this. If they offer additional support, they should offer it to help you stay safe and lose weight. That's one of the things we offer as part of our complex care package at Bodyline.

How Is My Weight Loss with GI Issues Supported by Bodyline?

We have an excellent clinical team who will take the time to assess you and come up with the right weight loss plan for you. With the additional support and more regular health checks, we can help you minimise side effects and hit your weight loss goals.