Ozempic (semaglutide) is a glucagon-like peptide-1 (GLP-1) receptor agonist licensed in the UK for treating type 2 diabetes mellitus. For individuals living with Crohn's disease—a chronic inflammatory bowel condition—questions often arise about whether Ozempic is safe and appropriate. Whilst Ozempic is not specifically contraindicated in Crohn's disease, its gastrointestinal side effects and mechanism of action warrant careful consideration. This article examines the evidence, potential risks, and essential discussions patients should have with their healthcare team before starting Ozempic when managing both type 2 diabetes and Crohn's disease.

What Is Ozempic and How Does It Work?

Ozempic (semaglutide) is a prescription medication licensed in the UK for the treatment of type 2 diabetes mellitus. It belongs to a class of drugs called glucagon-like peptide-1 (GLP-1) receptor agonists, which work by mimicking the action of a naturally occurring hormone in the body.

The mechanism of action involves several key processes. Semaglutide stimulates insulin secretion from the pancreas when blood glucose levels are elevated, helping to lower blood sugar. Simultaneously, it suppresses the release of glucagon, a hormone that raises blood glucose. Additionally, Ozempic slows gastric emptying—the rate at which food leaves the stomach—which contributes to improved glycaemic control and promotes a feeling of fullness.

Ozempic is administered as a once-weekly subcutaneous injection, typically starting at a low dose (0.25 mg for at least 4 weeks) and gradually increasing to therapeutic doses of 0.5 mg, 1 mg, or 2 mg at intervals of at least 4 weeks, depending on individual response and tolerability. The MHRA has approved it specifically for adults with type 2 diabetes, often in combination with other glucose-lowering medications or as monotherapy when metformin is not suitable. It is not indicated for type 1 diabetes or for the treatment of diabetic ketoacidosis.

Importantly, the SmPC states that Ozempic is not recommended in patients with severe gastrointestinal disease, including severe gastroparesis.

Whilst Ozempic has gained attention for its weight loss effects, it is not licensed for weight management in the UK. A higher dose formulation of semaglutide (Wegovy, 2.4 mg) has been approved for weight management under NICE guidance (TA875). Clinical trials (SUSTAIN-6) have shown cardiovascular benefits with semaglutide, though this is not a specific licensed indication in the UK.

Understanding Crohn's Disease and Digestive Health

Crohn's disease is a chronic inflammatory bowel disease (IBD) that can affect any part of the gastrointestinal tract, from the mouth to the anus, though it most commonly involves the terminal ileum and colon. The condition is characterised by transmural inflammation—meaning it affects the full thickness of the bowel wall—which can lead to complications including strictures, fistulas, and abscesses.

The symptoms of Crohn's disease vary considerably depending on disease location and severity. Common presentations include:

• Persistent diarrhoea (which may be bloody)

• Abdominal pain and cramping

• Weight loss and malnutrition

• Fatigue and reduced appetite

• Perianal disease (fissures, fistulas, abscesses)

Crohn's disease follows a relapsing-remitting course, with periods of active inflammation (flares) alternating with periods of remission. The exact cause remains unknown, though it is thought to result from a complex interaction between genetic susceptibility, environmental factors, gut microbiome alterations, and immune system dysfunction.

According to NICE guidance (NG129), management focuses on inducing and maintaining remission, preventing complications, and optimising nutritional status. Treatment typically involves immunosuppressive medications such as corticosteroids, thiopurines, methotrexate, or biologic therapies (anti-TNF agents, vedolizumab, ustekinumab).

The digestive system in Crohn's disease is already compromised, with impaired absorption, altered motility, and heightened sensitivity. This makes individuals with Crohn's potentially more vulnerable to medications that affect gastrointestinal function, including those that slow gastric emptying or alter bowel motility. Common nutritional deficiencies include vitamin B12 (particularly with ileal disease), iron, vitamin D, and zinc. Monitoring tools such as faecal calprotectin and CRP are often used to assess disease activity.

Can You Take Ozempic If You Have Crohn's Disease?

The question of whether Ozempic can be safely used in patients with Crohn's disease requires careful consideration, as there is no official contraindication listed in the Summary of Product Characteristics (SmPC) specifically for inflammatory bowel disease. However, the SmPC does state that semaglutide is not recommended in patients with severe gastrointestinal disease, including severe gastroparesis.

Currently, limited clinical trial data exists specifically examining the use of semaglutide in patients with active Crohn's disease. The pivotal trials for Ozempic (SUSTAIN programme) generally excluded patients with significant gastrointestinal disease, meaning real-world evidence in this population remains sparse. This creates a degree of clinical uncertainty that requires individualised risk-benefit assessment.

Several factors influence whether Ozempic might be appropriate for someone with Crohn's disease:

• Disease activity: Patients in stable remission may tolerate the medication differently than those with active inflammation

• Location of disease: Gastric or upper gastrointestinal involvement might be more problematic given Ozempic's effect on gastric emptying

• Nutritional status: Individuals already struggling with malabsorption or weight loss may be at higher risk

• Concurrent medications: While no clinically relevant interactions with common oral medications have been established for subcutaneous semaglutide, monitoring may be prudent

Additional important cautions with semaglutide include:

• Risk of worsening diabetic retinopathy, particularly with rapid glycaemic improvement

• Increased risk of gallbladder disease, especially with substantial weight loss

• Potential for dehydration leading to renal impairment

• Increased risk of hypoglycaemia when used with sulfonylureas or insulin

The MHRA and EMA have not issued specific warnings regarding Ozempic use in IBD patients beyond the general caution for severe gastrointestinal disease. Some healthcare professionals may consider prescribing Ozempic to patients with well-controlled Crohn's disease and type 2 diabetes when the benefits clearly outweigh potential risks, whilst others may prefer alternative diabetes medications with fewer gastrointestinal effects. This decision must be made collaboratively between the patient, their diabetologist, and gastroenterologist, with close monitoring during initiation and dose escalation.

Potential Risks and Gastrointestinal Side Effects

Ozempic is associated with a significant incidence of gastrointestinal adverse effects, which are the most commonly reported side effects in clinical trials. For patients with Crohn's disease, these effects may be particularly concerning and potentially more severe than in the general population.

Gastrointestinal side effects include:

• Nausea (very common, affecting more than 1 in 10 people): Often most pronounced during dose escalation, typically improving over time

• Diarrhoea (very common): Can range from mild to severe and may be difficult to distinguish from a Crohn's flare

• Vomiting (common, affecting up to 1 in 10 people): May contribute to dehydration and electrolyte imbalance

• Constipation (common): Paradoxically, some patients experience reduced bowel frequency

• Abdominal pain (common): Can mimic or exacerbate Crohn's-related pain

These effects result primarily from delayed gastric emptying and altered gastrointestinal motility. For someone with Crohn's disease, distinguishing between medication side effects and disease activity can be challenging, potentially delaying appropriate management of a flare.

More serious concerns include:

• Acute pancreatitis: Has been reported with GLP-1 agonists; symptoms include severe abdominal pain radiating to the back. If pancreatitis is suspected, semaglutide should be discontinued immediately and urgent medical assessment sought.

• Gallbladder disease: Including cholelithiasis and cholecystitis, particularly in those experiencing substantial weight loss

• Renal impairment: Secondary to dehydration from gastrointestinal side effects

• Ileus/intestinal obstruction: Post-marketing reports exist with GLP-1 receptor agonists (causality not established); theoretical risk may be higher in patients with stricturing Crohn's disease

For patients with Crohn's disease, additional considerations include potential dehydration from combined diarrhoea (disease and drug-related) and nutritional compromise if nausea and vomiting reduce oral intake in someone already at risk of malnutrition. While delayed gastric emptying may affect the absorption timing of some oral medications, no clinically relevant interactions were seen in studies with common oral medicines.

When to seek urgent medical attention:

• Severe, persistent abdominal pain (particularly if radiating to the back)

• Bloody diarrhoea or significant increase in stool frequency

• Signs of dehydration (dizziness, reduced urine output, dry mouth)

• Persistent vomiting preventing oral intake

• Fever accompanying gastrointestinal symptoms

Patients should contact their GP or IBD team promptly if they experience worsening symptoms that could indicate either a Crohn's flare or serious medication side effects. Suspected adverse reactions should be reported via the MHRA Yellow Card scheme.

What to Discuss With Your Doctor Before Starting Ozempic

If you have Crohn's disease and are considering Ozempic for type 2 diabetes management, a thorough discussion with your healthcare team is essential. This conversation should ideally involve both your diabetologist (or GP managing your diabetes) and your gastroenterologist to ensure coordinated care.

Key topics to discuss include:

Your Crohn's disease status:

• Current disease activity (remission versus active inflammation)

• Location and extent of disease involvement

• History of complications (strictures, fistulas, previous surgeries)

• Recent colonoscopy or imaging findings

• Current symptom burden and quality of life

Current medication regimen:

• All Crohn's medications (immunosuppressants, biologics, corticosteroids)

• Other diabetes medications and potential alternatives to Ozempic

• Any medications for symptom management (antidiarrhoeals, pain relief)

• Nutritional supplements or vitamin replacements

Nutritional and weight considerations:

• Current nutritional status and any deficiencies

• Recent weight changes (intentional or unintentional)

• Dietary restrictions or intolerances

• Whether weight loss is desirable or potentially harmful in your situation

Pregnancy and breastfeeding:

• Semaglutide should be stopped at least 2 months before a planned pregnancy

• Effective contraception should be used during treatment

• Ozempic should not be used during pregnancy

• Specialist advice should be sought regarding breastfeeding

Alternative diabetes management options:

• Other GLP-1 agonists with potentially different side effect profiles

• SGLT2 inhibitors, DPP-4 inhibitors, or insulin therapy

• The relative benefits and risks of each option given your Crohn's disease

Monitoring plan:

• Frequency of follow-up appointments during initiation

• How to distinguish between Crohn's flares and medication side effects

• When to contact the medical team

• Blood tests to monitor diabetes control, renal function and nutritional markers

• Potential need for faecal calprotectin monitoring to assess inflammation

• Retinopathy assessment if you have pre-existing diabetic retinopathy

• Hypoglycaemia risk and monitoring if taking sulfonylureas or insulin

Your doctor should provide clear safety netting advice, including specific symptoms that warrant immediate medical review and when to stop Ozempic (e.g., if pancreatitis is suspected). They should also discuss the dose escalation schedule and whether a more gradual titration might be appropriate given your Crohn's disease. Documentation of this shared decision-making process ensures all members of your healthcare team are aware of the plan and can provide consistent advice. Remember, there is no obligation to start Ozempic if you feel uncomfortable with the potential risks—alternative diabetes treatments are available and may be more suitable for your individual circumstances.

Frequently Asked Questions