Does Victoza cause fatigue? Victoza (liraglutide) is a GLP-1 receptor agonist licensed in the UK for type 2 diabetes mellitus. Whilst fatigue is not amongst the most commonly reported adverse effects, the Summary of Product Characteristics lists tiredness and asthenia as recognised side effects. Individual responses vary considerably, and fatigue in people with diabetes can arise from multiple sources including fluctuating blood glucose levels, gastrointestinal symptoms, reduced caloric intake, or concurrent health conditions. Understanding whether tiredness relates to Victoza itself or other factors is essential for appropriate management and maintaining effective glycaemic control.

Does Victoza Cause Fatigue? Understanding the Connection

Victoza (liraglutide) is a glucagon-like peptide-1 (GLP-1) receptor agonist licensed in the UK for the treatment of type 2 diabetes mellitus only. While fatigue is not among the most frequently reported adverse effects, the Summary of Product Characteristics (SmPC) does list tiredness/asthenia as a recognised side effect with a defined frequency.

The relationship between Victoza and fatigue is nuanced. In clinical studies, fatigue was reported at relatively low rates, though individual responses to medications can vary considerably. It's worth noting that Victoza is not licensed for weight management in the UK (a different liraglutide formulation, Saxenda, is approved for this purpose).

It is important to recognise that fatigue in people with type 2 diabetes can arise from multiple sources, including the underlying condition itself, fluctuating blood glucose levels, concurrent medications, or coexisting health problems. When patients report tiredness after starting Victoza, a thorough assessment is needed to determine whether the medication, the diabetes, or other factors are responsible. Understanding this distinction is crucial for appropriate management and ensuring patients receive optimal care whilst maintaining effective glycaemic control.

Common Side Effects of Victoza and Energy Levels

The most frequently reported adverse effects of Victoza relate to the gastrointestinal system, which is consistent with the mechanism of action of GLP-1 receptor agonists. According to the SmPC, side effects include:

• Very common (affecting more than 1 in 10 people):
• Nausea – often most pronounced during treatment initiation and dose escalation

• Diarrhoea – can contribute to dehydration and secondary fatigue

• Common (affecting between 1 in 100 and 1 in 10 people):

• Vomiting – may affect nutritional intake and energy levels
• Constipation, abdominal pain
• Decreased appetite

These gastrointestinal symptoms can indirectly influence energy levels and contribute to feelings of tiredness. Persistent nausea or vomiting may reduce caloric intake, whilst diarrhoea can lead to fluid and electrolyte imbalances, both of which can manifest as fatigue.

Victoza works by mimicking the action of endogenous GLP-1, slowing gastric emptying, enhancing glucose-dependent insulin secretion, and suppressing inappropriate glucagon release. Whilst these mechanisms improve glycaemic control, the delayed gastric emptying can contribute to gastrointestinal discomfort and reduced appetite.

Hypoglycaemia (low blood glucose) can occur, particularly when Victoza is used in combination with sulphonylureas or insulin. When used alone, hypoglycaemia is uncommon. Hypoglycaemic episodes characteristically cause symptoms including tremor, sweating, confusion, and significant fatigue. Patients should be educated about recognising and managing hypoglycaemia appropriately.

Victoza may also increase the risk of gallbladder disease, including cholelithiasis and cholecystitis, which can present with abdominal pain and systemic symptoms including fatigue.

Why Some Patients Experience Tiredness on Victoza

Several mechanisms may explain why certain individuals report fatigue whilst taking Victoza. Understanding these potential causes helps clinicians and patients identify contributing factors and implement appropriate interventions.

Blood glucose fluctuations represent a primary consideration. Whilst Victoza aims to stabilise glucose levels, the adjustment period may involve variations that affect energy. Both hyperglycaemia (high blood glucose) and hypoglycaemia can cause tiredness. Patients transitioning from poorly controlled diabetes may experience fatigue as their body adapts to improved glycaemic control—a phenomenon sometimes described as relative hypoglycaemia, where normal glucose levels feel low compared to the previously elevated levels the body had adapted to.

Reduced caloric intake due to Victoza's appetite-suppressing effects may contribute to tiredness in some individuals. The medication's action on satiety centres and delayed gastric emptying can reduce food consumption, which, whilst beneficial for managing diabetes, may inadvertently reduce energy availability if intake becomes insufficient for daily requirements.

Gastrointestinal side effects, as previously mentioned, can indirectly cause fatigue through multiple pathways: dehydration from diarrhoea or vomiting, poor nutrient absorption, or simply the physical toll of persistent nausea. These symptoms are typically most pronounced during the initial weeks of treatment or following dose increases.

Individual variation in drug metabolism and receptor sensitivity means some patients may experience effects not widely reported in clinical trials. Concurrent medications, comorbidities (such as thyroid disorders, anaemia, vitamin B12 deficiency especially if taking metformin, sleep apnoea, or depression), lifestyle factors, and the underlying progression of diabetes itself can all contribute to fatigue that coincides with, but is not necessarily caused by, Victoza therapy.

When to Seek Medical Advice About Fatigue

Whilst mild tiredness during the initial adjustment to Victoza may resolve spontaneously, certain presentations warrant prompt medical evaluation. Patients should be advised to contact their GP or diabetes specialist nurse if they experience:

• Severe or persistent fatigue that significantly impairs daily activities or does not improve after the first few weeks of treatment

• Symptoms of hypoglycaemia, including tremor, sweating, confusion, palpitations, or extreme tiredness—particularly if occurring frequently

• Signs of dehydration, such as reduced urine output, dark urine, dizziness, or dry mouth, especially if accompanied by ongoing diarrhoea or vomiting

• Unexplained weight loss beyond expected therapeutic effects, or inability to maintain adequate nutritional intake

• New or worsening symptoms including breathlessness, chest pain, or palpitations alongside fatigue

• Symptoms of thyroid abnormalities (unexplained fatigue with weight changes, temperature intolerance, or neck swelling)

Urgent medical attention is required if patients develop symptoms suggestive of serious adverse effects, including:

• Severe, persistent abdominal pain (potentially indicating pancreatitis)

• Signs of allergic reaction (rash, swelling, difficulty breathing)

• Sudden severe pain in the upper right abdomen, fever or yellowing of the skin/eyes (possible gallbladder disease)

According to NICE guidance on type 2 diabetes management (NG28), regular monitoring and medication review are essential components of care. Patients experiencing problematic fatigue should have a comprehensive assessment including review of blood glucose patterns, HbA1c levels, renal function, thyroid function, vitamin B12 levels (especially if taking metformin), and full blood count to exclude alternative causes such as anaemia. Assessment for sleep apnoea may also be appropriate. This systematic approach ensures that treatable causes of fatigue are identified and managed appropriately.

Patients are encouraged to report suspected side effects via the MHRA Yellow Card scheme (yellowcard.mhra.gov.uk or the Yellow Card app).

Managing Fatigue While Taking Victoza

For patients experiencing tiredness whilst taking Victoza, several practical strategies can help manage symptoms whilst maintaining effective diabetes control. A collaborative approach between patient and healthcare team is essential for optimal outcomes.

Gradual dose titration is recommended in the prescribing information to minimise gastrointestinal side effects. Starting at 0.6 mg daily for at least one week before increasing to 1.2 mg, and allowing further time before escalating to the maximum 1.8 mg dose if needed, helps the body adjust gradually. Patients who experience significant fatigue may benefit from slower titration or remaining on a lower effective dose. Patients should not stop or adjust their Victoza dose without consulting their healthcare professional.

Optimising nutrition is crucial. Despite reduced appetite, patients should aim to consume regular, balanced meals with adequate protein, complex carbohydrates, and healthy fats to maintain energy levels. Small, frequent meals may be better tolerated than larger portions. Maintaining good hydration is particularly important, especially with gastrointestinal symptoms, to prevent dehydration and associated renal issues.

Blood glucose monitoring may help identify patterns that contribute to fatigue. Following NICE guidance (NG28), self-monitoring is not routinely recommended for all patients with type 2 diabetes but may be appropriate for those on insulin, at risk of hypoglycaemia, during medication changes, or according to individualised clinical advice.

Lifestyle modifications including regular physical activity (as tolerated), adequate sleep, and stress management can significantly improve energy levels. Exercise, in particular, enhances insulin sensitivity and may reduce fatigue associated with diabetes itself.

Medication review should be conducted if fatigue persists despite these measures. Alternative GLP-1 receptor agonists, different diabetes medication classes, or adjusted combination therapy may be more suitable for some individuals. The decision to continue, modify, or discontinue Victoza should be made collaboratively, weighing glycaemic control benefits against quality of life impacts. Regular follow-up ensures that treatment remains appropriate and effective for each patient's individual circumstances.

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