Saxenda (liraglutide 3 mg) is a GLP-1 receptor agonist licensed in the UK for weight management in adults with obesity or overweight with weight-related comorbidities. Whilst increased urination is not listed as an adverse effect in the Summary of Product Characteristics, some patients report changes in urinary frequency when starting treatment. This may relate to weight loss itself, dietary modifications, increased fluid intake, or improved blood glucose regulation. Understanding when urinary changes are expected versus concerning is essential for safe, effective treatment.

Why Saxenda May Cause Increased Urination

Saxenda (liraglutide 3 mg) is a glucagon-like peptide-1 (GLP-1) receptor agonist licensed in the UK for weight management in adults with obesity or overweight with weight-related comorbidities. Increased urination is not listed as an adverse effect in the Saxenda Summary of Product Characteristics (SmPC).

Several factors may explain why some people notice changes in urination when taking Saxenda. Weight loss itself can contribute—early weight loss often involves glycogen depletion and associated water and sodium loss, which can temporarily increase urine output. Additionally, patients often make dietary changes when starting Saxenda, including increased water intake to manage appetite or reduce nausea, which naturally increases urinary frequency.

Saxenda's effect on blood glucose regulation may also play a role in some individuals. Although primarily prescribed for weight management, liraglutide improves glycaemic control by enhancing insulin secretion and suppressing glucagon. In patients with prediabetes or undiagnosed type 2 diabetes, improved glucose control may reduce elevated blood glucose levels that previously caused increased urination.

It's important to consider other common causes of increased urination that may coincide with starting Saxenda, including:

• Increased caffeine or alcohol consumption

• Other medications (particularly diuretics or SGLT2 inhibitors)

• Underlying conditions like diabetes or urinary tract infections

GLP-1 receptor agonists like Saxenda work primarily in the gastrointestinal tract and central nervous system to reduce appetite and slow gastric emptying. They are not diuretics and do not directly target kidney function, though dehydration from gastrointestinal side effects can affect renal function.

Distinguishing Normal from Concerning Urinary Changes

Understanding the difference between expected urinary changes and symptoms requiring medical attention is essential for patient safety. Normal urinary frequency typically ranges from four to eight times daily, though this varies with fluid intake, caffeine consumption, and individual physiology. A modest increase in urination—particularly if accompanied by successful weight loss and adequate hydration—is generally not concerning.

Characteristics of normal urinary changes during Saxenda treatment include:

• Gradual increase in frequency over the first few weeks

• Clear or pale yellow urine indicating good hydration

• No pain, burning, or discomfort during urination

• Reasonable sleep patterns (though some nocturia is normal, especially in older adults)

• Correlation with increased water intake or dietary changes

Conversely, concerning symptoms that warrant medical evaluation include:

• Excessive thirst (polydipsia) accompanied by very frequent urination (polyuria)—potentially indicating hyperglycaemia or diabetes (consider checking blood glucose and urine ketones if available)

• Painful urination (dysuria), urgency, or sensation of incomplete bladder emptying—suggesting urinary tract infection

• Blood in the urine (haematuria), even if microscopic or intermittent

• Nocturia (waking multiple times nightly to urinate) that significantly disrupts sleep

• Urinary incontinence or sudden inability to control bladder function

• Dark, concentrated urine despite adequate fluid intake—possibly indicating dehydration

• Fever with flank pain or rigors—suggesting possible kidney infection (pyelonephritis)

Patients should also monitor for signs of dehydration, which can occur if increased urination is not matched by adequate fluid replacement. Symptoms include dizziness, dry mouth, reduced skin turgor, concentrated urine, and fatigue. This is particularly relevant as Saxenda commonly causes gastrointestinal side effects (nausea, vomiting, diarrhoea) that may compound fluid losses.

Managing Increased Urination While Taking Saxenda

Practical strategies can help patients manage increased urinary frequency whilst continuing Saxenda treatment effectively. Fluid management is paramount—patients should aim for adequate hydration (6-8 glasses or cups daily for most adults, more during hot weather or exercise) but avoid excessive intake, particularly in the evening hours. Distributing fluid consumption throughout the day, with reduced intake 2–3 hours before bedtime, can minimise nocturia whilst maintaining hydration.

Dietary modifications may also prove beneficial. Reducing intake of bladder irritants—including caffeine (coffee, tea, energy drinks), alcohol, carbonated beverages, artificial sweeteners, and spicy foods—can decrease urinary urgency and frequency. Many patients inadvertently increase caffeine consumption when making dietary changes, so reviewing total intake is worthwhile.

Bladder training techniques can improve control and reduce frequency. These include:

• Scheduled voiding—urinating at set intervals (e.g., every 2–3 hours) rather than responding to every urge

• Pelvic floor exercises (Kegel exercises)—strengthening muscles that control urination

• Urge suppression—using distraction or relaxation techniques when feeling the need to urinate

Patients should maintain a bladder diary for several days, recording fluid intake, urination times, volume (if possible), and any associated symptoms. This objective data helps identify patterns and can be invaluable during medical consultations. The diary should note timing of Saxenda injections, meals, and any correlation with urinary symptoms.

Reviewing medications with your healthcare provider is important—some medicines (diuretics, SGLT2 inhibitors) can increase urination and may need adjustment. Do not stop or change your Saxenda dose without medical advice, but seek prompt review if you experience severe dehydration, vomiting, or very low urine output.

When to Seek Medical Advice About Urinary Symptoms

Certain urinary symptoms require prompt medical evaluation to exclude serious underlying conditions.

Call NHS 111 or attend A&E immediately if you experience:

• Inability to pass urine (urinary retention)

• Severe reduction in urine output

• Signs of sepsis (high fever, rigors, confusion) with urinary symptoms

• Severe dehydration (extreme thirst, dizziness, confusion, very dark urine)

Contact your GP urgently (within 24–48 hours) if you experience:

• Sudden onset of excessive thirst and urination—particularly if accompanied by unexplained weight loss, fatigue, or blurred vision, as these may indicate hyperglycaemia or diabetes

• Painful urination with fever—suggesting possible pyelonephritis (kidney infection) requiring antibiotic treatment

• Visible blood in urine—which requires investigation according to NICE guidelines to exclude malignancy, stones, or infection

• Significant nocturia (waking ≥3 times nightly) that impairs quality of life

Patients should seek routine GP review (within 1–2 weeks) for:

• Persistent increased urination beyond the first month of treatment without improvement

• Urinary frequency significantly impacting daily activities or work

• Signs of possible urinary tract infection (urgency, frequency, suprapubic discomfort)

• Concerns about fluid balance or dehydration despite adequate intake

• New urinary incontinence or worsening of pre-existing incontinence

Before the appointment, patients should prepare by:

• Completing a bladder diary for at least 3 days

• Noting all medications and supplements

• Recording weight changes since starting Saxenda

• Listing all urinary and systemic symptoms

Investigations the GP may arrange include urinalysis (dipstick testing for infection, glucose, protein, blood), urine culture if infection is suspected, blood tests (renal function, HbA1c, electrolytes), and potentially a pregnancy test for people of childbearing potential. Post-void residual volume measurement may be arranged in primary care or via referral depending on local pathways.

Other Urinary Side Effects Associated with Saxenda

Whilst increased urination frequency is not listed as an adverse reaction to Saxenda, patients should be aware of other potential urinary tract considerations. Urinary tract infections (UTIs) are not listed as adverse reactions in the Saxenda SmPC. UTIs may occur coincidentally during treatment—if you experience symptoms such as painful urination, urgency, frequency, suprapubic discomfort, cloudy or malodorous urine, seek medical advice promptly.

Symptoms of UTI include dysuria (painful urination), urgency, frequency, suprapubic discomfort, cloudy or malodorous urine, and occasionally haematuria. Women are at higher risk than men due to anatomical differences. Prevention strategies include adequate hydration, complete bladder emptying, urinating after sexual activity, and avoiding potential irritants.

Urinary incontinence—both stress incontinence (leakage with coughing, sneezing, exercise) and urge incontinence (sudden, intense need to urinate)—may improve with weight loss achieved through Saxenda treatment. Obesity is a significant risk factor for incontinence, and studies demonstrate that weight reduction of 5–10% can substantially improve symptoms. However, some patients may notice temporary changes during rapid weight loss phases.

Kidney function considerations are important, particularly in patients with pre-existing renal impairment. According to the SmPC, experience with Saxenda is limited in severe renal impairment (eGFR <30 mL/min/1.73m²), and it should be used with caution in mild to moderate impairment. Renal function should be monitored in patients experiencing significant gastrointestinal side effects (nausea, vomiting, diarrhoea) that could lead to dehydration and acute kidney injury.

If you're taking other medications that can affect urination (such as SGLT2 inhibitors or diuretics), discuss this with your prescriber, as adjustments may be needed.

Patients should report any persistent or troublesome urinary symptoms to their prescriber, who can assess whether continuation of Saxenda is appropriate. If you suspect an adverse reaction to Saxenda, report it through the MHRA Yellow Card Scheme (yellowcard.mhra.gov.uk).

Frequently Asked Questions