Victoza (liraglutide) is a glucagon-like peptide-1 (GLP-1) receptor agonist licensed in the UK for treating type 2 diabetes mellitus. Whilst Victoza does not directly cause gastroparesis—a chronic condition involving permanent nerve or muscle damage—it intentionally slows gastric emptying as part of its therapeutic mechanism. This effect helps control blood glucose but can produce digestive symptoms resembling gastroparesis in some patients. Understanding the distinction between temporary medication-related gastric slowing and true gastroparesis is essential for safe, effective diabetes management. This article examines Victoza's effects on digestion, associated symptoms, and when to seek medical advice.

What Is Victoza and How Does It Work?

Victoza (liraglutide) is a prescription medicine licensed in the UK for the treatment of type 2 diabetes mellitus in adults, as an adjunct to diet and exercise. It belongs to a class of medications 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 of Victoza involves several key processes that help control blood glucose levels:

• Stimulating insulin secretion from the pancreas when blood sugar levels are elevated

• Suppressing glucagon release, which reduces glucose production by the liver

• Slowing gastric emptying, which moderates the rate at which food leaves the stomach

• Reducing appetite, which may contribute to weight loss in some patients (though Victoza is not licensed for weight management in the UK)

Victoza is administered as a once-daily subcutaneous injection and can be given at any time of day, independent of meals, though at a consistent time each day. It is typically prescribed when diet, exercise, and other diabetes medications have not achieved adequate glycaemic control. The MHRA-approved dosing begins at 0.6 mg daily as an initiation dose (to improve gastrointestinal tolerability rather than for glycaemic control), gradually increasing to a maintenance dose of 1.2 mg or 1.8 mg depending on individual response and tolerability.

It is important to understand that whilst Victoza is highly effective for many patients with type 2 diabetes, its effect on gastric emptying—one of its therapeutic mechanisms—can also contribute to gastrointestinal side effects. This slowing of stomach emptying is intentional and helps prevent rapid spikes in blood sugar after meals, but it may cause digestive symptoms in some individuals. According to the Summary of Product Characteristics (SmPC), Victoza is not recommended for use in patients with diabetic gastroparesis.

Understanding Gastroparesis: Symptoms and Causes

Gastroparesis is a medical condition characterised by delayed gastric emptying without any mechanical obstruction of the stomach. In gastroparesis, the stomach takes longer than normal to empty its contents into the small intestine, leading to a range of uncomfortable and sometimes debilitating symptoms.

Common symptoms of gastroparesis include:

• Nausea and vomiting, particularly of undigested food

• Feeling full very quickly when eating (early satiety)

• Bloating and abdominal distension

• Upper abdominal pain or discomfort

• Loss of appetite and unintentional weight loss

• Heartburn or gastro-oesophageal reflux

• Fluctuations in blood glucose levels (particularly relevant for people with diabetes)

Gastroparesis has several recognised causes. The most common is diabetic gastroparesis, which occurs when prolonged high blood sugar levels damage the vagus nerve that controls stomach muscle contractions. Other causes include post-surgical complications, certain medications (including opioids, anticholinergics, and some GLP-1 receptor agonists), neurological conditions such as Parkinson's disease, and autoimmune disorders. In many cases, the cause remains unknown (idiopathic gastroparesis).

It is crucial to distinguish between true gastroparesis—a chronic condition with demonstrable delayed gastric emptying on diagnostic testing—and temporary slowing of gastric emptying that may occur as a side effect of certain medications. Gastroparesis is typically diagnosed through gastric emptying studies (scintigraphy), where patients consume a standardised meal containing a small amount of radioactive material, and imaging tracks how quickly the stomach empties over several hours. This distinction is particularly important when considering medications like Victoza that intentionally slow gastric emptying as part of their therapeutic effect.

Victoza's Effects on Gastric Emptying and Digestion

Clinical trials have not definitively established that Victoza causes true gastroparesis, but it is well documented that the medication intentionally slows gastric emptying as part of its mechanism of action. This is an important distinction that patients and healthcare professionals must understand.

Victoza and other GLP-1 receptor agonists work partly by delaying the rate at which food moves from the stomach into the small intestine. This slowing effect is therapeutic—it helps prevent rapid rises in blood glucose after meals and contributes to improved glycaemic control. However, this same mechanism can produce gastrointestinal side effects that may resemble some symptoms of gastroparesis. The gastric-emptying effects are typically most pronounced early in treatment and may diminish with continued use.

Common digestive side effects reported with Victoza include:

• Nausea (very common, affecting more than 1 in 10 patients, particularly when starting treatment)

• Vomiting (common)

• Diarrhoea (common)

• Constipation (common)

• Abdominal discomfort or pain (common)

• Reduced appetite (common)

• Indigestion or dyspepsia (common)

These effects are typically most pronounced during the initial weeks of treatment and often improve as the body adjusts to the medication. The gradual dose escalation recommended for Victoza is specifically designed to minimise these gastrointestinal symptoms.

It is important to note that whilst Victoza slows gastric emptying, this is generally a temporary, dose-dependent effect rather than the permanent nerve or muscle damage seen in true gastroparesis. However, rare cases of gastroparesis-like symptoms have been reported in post-marketing surveillance. The UK SmPC specifically states that Victoza is not recommended for use in patients with diabetic gastroparesis, and patients with pre-existing gastrointestinal disease should be monitored for worsening symptoms.

Managing Digestive Side Effects While Taking Victoza

If you experience digestive symptoms whilst taking Victoza, several practical strategies can help manage these effects whilst maintaining the benefits of your diabetes treatment.

Dietary modifications can significantly reduce gastrointestinal discomfort:

• Eat smaller, more frequent meals rather than three large meals daily

• Chew food thoroughly and eat slowly to aid digestion

• Avoid high-fat foods, which take longer to digest and may worsen nausea

• Limit fibre intake temporarily if experiencing severe symptoms, then gradually reintroduce

• Stay well hydrated, sipping fluids throughout the day rather than drinking large amounts with meals

• Avoid lying down immediately after eating; remain upright for at least two hours post-meal

• Identify and avoid trigger foods that seem to worsen your symptoms

Medication timing and administration also matter. Taking Victoza at a consistent time each day can help your body adjust. The timing is flexible but should be consistent daily. Never adjust your dose without consulting your healthcare team, as the gradual titration schedule is designed to minimise side effects. Your diabetes team may consider a slower titration or temporary dose reduction if symptoms are troublesome.

Additional supportive measures include:

• Using anti-nausea medications if prescribed by your doctor. Note that in the UK:
• Domperidone is prescription-only, contraindicated in certain cardiac conditions and with interacting drugs, and should be used at the lowest effective dose for the shortest duration (typically up to 7 days)

• Metoclopramide should be limited to a maximum of 5 days in adults

• Keeping a symptom diary to identify patterns and triggers

• Maintaining good glycaemic control, as high blood sugar itself can worsen gastric emptying

• Discussing with your diabetes team whether adjustments to other medications might help

Many patients find that gastrointestinal side effects improve over time as their body adapts to Victoza. If symptoms persist or significantly impact your quality of life, your healthcare provider may consider dose adjustment or alternative treatment options. NICE guidance emphasises individualised diabetes management, and your treatment plan should balance glycaemic control with tolerability and quality of life.

When to Seek Medical Advice About Victoza and Stomach Problems

Whilst mild digestive symptoms are common when starting Victoza, certain situations require prompt medical attention. Understanding when to contact your GP or diabetes team is essential for your safety.

Seek urgent medical advice if you experience:

• Severe, persistent vomiting that prevents you from keeping down food, fluids, or other medications

• Signs of dehydration, including dark urine, dizziness, extreme thirst, or reduced urination

• Severe abdominal pain, particularly if constant or accompanied by fever

• Vomiting blood or material that looks like coffee grounds

• Black, tarry stools or blood in your stools

• Unexplained, rapid weight loss

• Difficulty swallowing or pain when swallowing

• Symptoms of pancreatitis: severe upper abdominal pain radiating to the back, often with nausea and vomiting

If you suspect pancreatitis, stop taking Victoza immediately and seek urgent medical attention. Do not restart Victoza if acute pancreatitis is confirmed.

For severe symptoms, contact your GP for same-day assessment, call NHS 111, or in emergencies (severe persistent pain, haematemesis, melaena, signs of shock), call 999 or attend A&E.

Contact your diabetes team or GP within a few days if:

• Nausea or digestive symptoms persist without improvement

• Symptoms significantly interfere with your daily activities or quality of life

• You are unable to eat adequate nutrition due to digestive problems

• Your blood glucose control deteriorates due to eating difficulties

• You develop new or worsening symptoms after your dose is increased

Before your appointment, it is helpful to:

• Keep a detailed record of your symptoms, including timing, severity, and any triggers

• Note what foods you can and cannot tolerate

• Record your blood glucose readings

• List all medications and supplements you are taking

Your healthcare provider may perform investigations such as blood tests, gastric emptying studies, or endoscopy if symptoms are severe or persistent. They will assess whether your symptoms represent expected side effects that may improve with time and management strategies, or whether they indicate a more serious condition requiring treatment modification. Never stop taking Victoza without medical guidance (except if pancreatitis is suspected), as this may affect your diabetes control. Your healthcare team can help you weigh the benefits and risks and explore alternative treatment options if needed.

If you suspect you are experiencing side effects from Victoza, you can report these through the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk or via the Yellow Card app.

Frequently Asked Questions