Saxenda (liraglutide 3.0 mg) is a GLP-1 receptor agonist licensed in the UK for weight management in adults with obesity or overweight with comorbidities. Whilst the medication commonly causes gastrointestinal side effects such as nausea and diarrhoea, some patients have questioned whether Saxenda can cause urinary tract infections (UTIs). Current clinical evidence does not establish a direct link between Saxenda and increased UTI risk. However, understanding the relationship between weight loss treatment and urinary symptoms helps patients recognise when medical attention is needed and implement preventive strategies during therapy.

Understanding Saxenda and Its Common Side Effects

Saxenda (liraglutide 3.0 mg) is a prescription medicine licensed in the UK for weight management in adults with a BMI ≥30 kg/m², or ≥27 kg/m² with weight-related health conditions. It belongs to a class of medications called glucagon-like peptide-1 (GLP-1) receptor agonists, which work by mimicking a naturally occurring hormone that regulates appetite and food intake.

Saxenda is administered as a once-daily subcutaneous injection with a dose titration schedule starting at 0.6 mg and increasing weekly to the maintenance dose of 3.0 mg. Treatment should be discontinued after 12 weeks at the 3.0 mg dose if patients have not lost at least 5% of their initial body weight.

The mechanism of action involves slowing gastric emptying, increasing feelings of fullness, and reducing hunger signals in the brain. This helps patients consume fewer calories and achieve gradual weight loss when used as part of a comprehensive weight management programme.

Common side effects associated with Saxenda predominantly affect the gastrointestinal system and include:

• Nausea and vomiting – particularly during the initial dose escalation period

• Diarrhoea or constipation – affecting bowel habits

• Abdominal pain or discomfort – ranging from mild to moderate

• Headache and dizziness – especially when starting treatment

• Injection site reactions – such as redness, itching, or bruising

These effects are generally mild to moderate in severity and often diminish as the body adjusts to the medication over several weeks. Important warnings include risks of pancreatitis, gallbladder disease (including cholelithiasis and cholecystitis), dehydration potentially leading to acute kidney injury, and increased heart rate.

Saxenda should not be used during pregnancy and requires careful consideration if breastfeeding. Patients taking warfarin should have their INR monitored when initiating treatment.

If you experience any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in the package leaflet. You can also report side effects directly via the Yellow Card Scheme at yellowcard.mhra.gov.uk.

The Link Between Saxenda and Urinary Tract Infections

There is no established link between Saxenda (liraglutide) and an increased risk of urinary tract infections (UTIs) based on current clinical evidence. The Summary of Product Characteristics (SmPC) for Saxenda, as approved by the MHRA, does not list UTIs as a recognised adverse effect of the medication. Clinical trials did not demonstrate an increased incidence of UTIs compared to placebo.

This distinguishes Saxenda from some other diabetes medications, particularly SGLT2 inhibitors (such as dapagliflozin or empagliflozin), which are known to increase UTI risk due to their mechanism of action involving glucose excretion in urine. Saxenda works through a completely different pathway—acting on GLP-1 receptors to regulate appetite and glucose metabolism.

However, it is important to acknowledge that individual patient experiences may vary, and some people taking Saxenda have reported UTI symptoms. These occurrences are more likely coincidental rather than causally related to the medication itself. Several factors may contribute to this perception:

• Lifestyle changes during weight loss programmes, including altered fluid intake patterns

• Increased physical activity and exercise routines

• Pre-existing risk factors for UTIs unrelated to medication use

When assessing UTI symptoms in patients taking Saxenda, healthcare professionals should consider other common causes including diabetes or poor glycaemic control, sexual activity, post-menopausal vaginal atrophy, urinary retention, catheter use, and anatomical abnormalities.

The absence of a documented association in clinical trials and post-marketing surveillance supports the view that any perceived link between Saxenda and UTIs is likely coincidental rather than causal.

Why UTI Symptoms May Occur During Saxenda Treatment

Whilst Saxenda itself does not directly cause UTIs, several indirect factors associated with weight loss treatment may contribute to urinary symptoms or increase susceptibility to infections. Understanding these mechanisms helps patients and clinicians identify potential triggers and implement preventive strategies.

Dehydration and fluid balance changes represent a significant consideration. The gastrointestinal side effects of Saxenda—particularly nausea, vomiting, and diarrhoea—can lead to reduced fluid intake or increased fluid loss. Inadequate hydration concentrates urine, potentially irritating the bladder lining and creating a more favourable environment for bacterial growth. Concentrated urine also reduces the natural flushing mechanism that helps clear bacteria from the urinary tract.

Increased physical activity, whilst beneficial for weight loss, may contribute to urinary symptoms through several mechanisms:

• Delayed voiding during extended exercise sessions

• Increased perspiration leading to dehydration

Common risk factors for UTIs that should be considered include:

• Female sex (shorter urethra)

• Sexual activity (especially with new partners)

• Use of spermicides or diaphragms

• Post-menopausal vaginal atrophy

• Diabetes or poor glycaemic control

• Urinary retention or incomplete bladder emptying

• Enlarged prostate in men

• Catheter use

• Anatomical abnormalities of the urinary tract

To reduce UTI risk while taking Saxenda, the NHS recommends maintaining adequate hydration—typically 6-8 glasses of water daily—and practising good urogenital hygiene. Other preventive measures include emptying the bladder regularly, urinating after sexual intercourse, and avoiding potential bladder irritants such as alcohol and caffeine.

Recognising UTI Symptoms While Taking Saxenda

Early recognition of UTI symptoms is crucial for prompt treatment and preventing complications. Patients taking Saxenda should be aware of the characteristic signs of urinary tract infections, which can affect the lower urinary tract (cystitis) or, less commonly, progress to involve the kidneys (pyelonephritis).

Common symptoms of lower urinary tract infection include:

• Dysuria – a burning or stinging sensation when passing urine

• Urinary frequency – needing to urinate more often than usual

• Urinary urgency – sudden, compelling need to urinate

• Suprapubic pain or discomfort – aching or pressure in the lower abdomen

• Cloudy or strong-smelling urine – changes in urine appearance or odour

• Blood in the urine – may be visible

• Waking during the night to urinate – more frequently than usual

It is important to distinguish these symptoms from the expected side effects of Saxenda. Whilst abdominal discomfort can occur with both UTIs and as a gastrointestinal side effect of the medication, UTI-related pain is typically localised to the lower abdomen or pelvic region and is specifically associated with urination.

Symptoms suggesting upper urinary tract involvement (kidney infection) require urgent medical attention:

• High fever (38°C or above) with shaking

• Flank pain – pain in the back or side, below the ribs

• Nausea and vomiting – particularly when accompanied by fever

• General malaise – feeling systemically unwell

Sepsis red flags requiring emergency care include:

• Very drowsy, difficult to wake or confused

• Not passing urine all day

• Mottled, bluish or pale skin

• Feeling very cold or clammy

Patients should not dismiss urinary symptoms as merely side effects of Saxenda. Whilst the medication may cause various gastrointestinal effects, specific urinary symptoms warrant proper investigation. Women, older adults, and those with diabetes should be particularly vigilant, as these groups face higher baseline UTI risk regardless of Saxenda use.

When to Seek Medical Advice

Prompt medical consultation is essential when urinary symptoms develop during Saxenda treatment. Whilst there is no established causal link between the medication and UTIs, any suspected infection requires proper assessment and treatment to prevent complications.

Contact your GP or healthcare provider if you experience:

• Persistent urinary symptoms lasting more than 24-48 hours

• Painful urination accompanied by frequency or urgency

• Blood in urine – even if painless

• Lower abdominal or pelvic pain specifically related to urination

• Fever or feeling generally unwell alongside urinary symptoms

• Recurrent UTIs – three or more episodes within 12 months

Seek urgent medical attention (call 111 or attend A&E) if you develop:

• High fever (38°C or above) with shaking

• Severe flank or back pain suggesting kidney involvement

• Persistent vomiting preventing oral fluid intake

• Confusion or altered mental state – particularly in older adults with urinary symptoms

• Inability to pass urine or significantly reduced urine output

Call 999 or go to A&E immediately if you have symptoms of sepsis such as very drowsy/confused, mottled/blue skin, or not passing urine all day.

In line with NICE guidance (NG109), diagnosis of UTIs in women is primarily based on symptoms rather than dipstick testing. When antibiotics are needed, nitrofurantoin is typically the first-choice treatment (for those with eGFR ≥45 mL/min/1.73 m²) for 3 days in women and 7 days in men. Trimethoprim may be considered if low risk of resistance. Urine cultures are recommended for men, pregnant women, children, those with recurrent or complicated UTIs, and when treatment fails.

Do not stop taking Saxenda without consulting your prescriber, even if you develop a UTI. The infection can be treated concurrently with continuing your weight management medication. However, if you experience severe vomiting or dehydration due to either the UTI or Saxenda side effects, your doctor may advise temporarily pausing treatment until you recover.

Preventive measures include maintaining adequate hydration, emptying your bladder regularly, urinating after sexual intercourse, and practising good urogenital hygiene. Regular follow-up appointments allow monitoring of both your weight loss progress and any emerging health concerns, ensuring safe and effective treatment with Saxenda.

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