Wegovy (semaglutide 2.4 mg) is a GLP-1 receptor agonist licensed in the UK for weight management in adults with obesity or overweight with comorbidities. While does Wegovy cause kidney stones is a common concern, there is currently no established direct causal link between semaglutide and kidney stone formation. However, the medication's gastrointestinal side effects—particularly nausea, vomiting, and diarrhoea—can potentially lead to dehydration, a well-recognised risk factor for kidney stones. Understanding this indirect relationship and maintaining adequate hydration are essential for patients prescribed Wegovy.

What Is Wegovy and How Does It Work?

Wegovy (semaglutide 2.4 mg) is a prescription medicine licensed in the UK for weight management in adults with obesity (BMI ≥30 kg/m²) or overweight (BMI ≥27 kg/m²) with at least one weight-related comorbidity, such as type 2 diabetes, hypertension, or obstructive sleep apnoea. It is administered as a once-weekly subcutaneous injection and is intended to be used alongside a reduced-calorie diet and increased physical activity.

Semaglutide belongs to a class of medications called glucagon-like peptide-1 (GLP-1) receptor agonists. These drugs mimic the action of the naturally occurring hormone GLP-1, which is released from the gut in response to food intake. By activating GLP-1 receptors in the brain, particularly in areas that regulate appetite, Wegovy helps to reduce hunger and increase feelings of fullness. This leads to a reduction in calorie intake and, consequently, weight loss.

The mechanism of action also includes slowing gastric emptying, which prolongs the sensation of satiety after meals, and modulating insulin secretion in a glucose-dependent manner. Clinical trials have demonstrated that Wegovy can lead to significant weight loss—typically around 10–15% of initial body weight over 68 weeks—when combined with lifestyle modifications, as shown in the STEP clinical trial programme.

As with any medication, Wegovy may cause side effects. The most commonly reported adverse effects include gastrointestinal symptoms such as nausea, vomiting, diarrhoea, constipation, and abdominal pain. These tend to be mild to moderate and often diminish over time as the body adjusts to the medication. Importantly, persistent vomiting or diarrhoea can lead to dehydration, which may increase the risk of acute kidney injury. Patients experiencing these symptoms should contact their healthcare provider.

In the UK, according to NICE Technology Appraisal 875, Wegovy is initiated by specialist weight management services and may be prescribed for up to 2 years within NHS settings.

Understanding Kidney Stone Risk Factors

Kidney stones, or renal calculi, are hard deposits formed from minerals and salts that crystallise within the kidneys. They affect approximately 1 in 10 people in the UK at some point in their lives, with men being more commonly affected than women. Understanding the risk factors for kidney stone formation is crucial, particularly for individuals taking medications that may influence hydration status or metabolic processes.

Primary risk factors for kidney stones include:

• Dehydration: Insufficient fluid intake leads to concentrated urine, which promotes crystal formation. This is the single most important modifiable risk factor.

• Dietary factors: High sodium intake, excessive animal protein consumption, and diets rich in oxalate-containing foods (such as spinach, rhubarb, and nuts) can increase stone risk.

• Obesity: Excess body weight is associated with metabolic changes that increase urinary excretion of calcium, oxalate, and uric acid, all of which contribute to stone formation.

• Medical conditions: Conditions such as hyperparathyroidism, recurrent urinary tract infections, inflammatory bowel disease, bariatric surgery (causing enteric hyperoxaluria), and certain genetic disorders predispose individuals to kidney stones.

• Medications: Some drugs can increase stone risk, including loop diuretics, carbonic anhydrase inhibitors (e.g., topiramate, acetazolamide), certain protease inhibitors (e.g., indinavir), excessive vitamin C supplements, and calcium-based antacids when taken inappropriately. Notably, thiazide diuretics may actually reduce stone risk in some patients.

Regarding Wegovy and kidney stones, there is currently no established direct causal link between semaglutide use and kidney stone formation based on clinical trial data and post-marketing surveillance as reported in the Wegovy Summary of Product Characteristics (SmPC). However, the gastrointestinal side effects of Wegovy—particularly nausea, vomiting, and diarrhoea—can potentially lead to dehydration if fluid intake is inadequate. Dehydration, in turn, is a well-recognised risk factor for kidney stone development and may also lead to acute kidney injury. Therefore, while Wegovy itself does not directly cause kidney stones, the indirect effects of reduced fluid intake or fluid loss through gastrointestinal symptoms could theoretically increase risk in susceptible individuals.

Symptoms of Kidney Stones to Watch For

Recognising the symptoms of kidney stones is important for anyone, but particularly for those taking medications that may affect hydration status. Kidney stones can vary considerably in size, from tiny grains to larger stones several centimetres in diameter. Small stones may pass through the urinary tract without causing symptoms, but larger stones or those that obstruct the ureter can cause significant discomfort.

Common symptoms of kidney stones include:

• Severe pain: Often described as one of the most intense types of pain, kidney stone pain (renal colic) typically begins suddenly in the flank or lower back and may radiate to the groin or lower abdomen. The pain often comes in waves and fluctuates in intensity as the stone moves through the urinary tract.

• Haematuria: Blood in the urine, which may appear pink, red, or brown. This occurs due to irritation of the urinary tract lining as the stone passes.

• Urinary symptoms: Increased frequency and urgency of urination, pain or burning sensation during urination (dysuria), and difficulty passing urine if the stone causes obstruction.

• Nausea and vomiting: These symptoms often accompany severe pain and are thought to result from shared nerve pathways between the kidneys and gastrointestinal tract.

• Fever and chills: If present alongside other symptoms, these may indicate a urinary tract infection complicating the kidney stone, which requires urgent medical attention. According to NICE guideline NG118, fever with suspected urinary obstruction requires immediate hospital assessment.

• Cloudy or foul-smelling urine: This may suggest infection or the presence of crystals.

It is important to note that the gastrointestinal side effects of Wegovy—such as nausea and vomiting—can sometimes be confused with symptoms of kidney stones. If you are taking Wegovy and experience persistent or severe abdominal or flank pain, blood in your urine, or symptoms that differ from your usual medication side effects, it is essential to seek medical evaluation to rule out kidney stones or other complications.

Patients with certain conditions, including a single kidney, pregnancy, chronic kidney disease, or immunosuppression, should have a lower threshold for seeking medical attention if kidney stone symptoms develop.

Reducing Kidney Stone Risk While Taking Wegovy

For individuals taking Wegovy, maintaining adequate hydration and adopting preventive strategies can significantly reduce the risk of kidney stone formation. While there is no official evidence linking Wegovy directly to kidney stones, the medication's gastrointestinal effects warrant attention to fluid balance and overall kidney health.

Practical strategies to reduce kidney stone risk include:

• Maintain excellent hydration: Aim to drink 2.5 to 3 litres of fluid daily, primarily water, with a goal of producing at least 2–2.5 litres of urine per day. This helps dilute urine and prevents crystal formation. If you experience nausea or vomiting from Wegovy, make a conscious effort to sip fluids regularly throughout the day, even if you don't feel thirsty. Note: If you have heart failure, severe kidney disease, or are on fluid restriction, consult your healthcare provider for personalised fluid intake recommendations.

• Monitor urine colour: Pale yellow or clear urine generally indicates adequate hydration, while dark yellow or amber urine suggests you need to drink more fluids.

• Moderate dietary sodium: Limit salt intake to less than 6 grams per day (approximately one teaspoon), as recommended by UK dietary guidelines. High sodium intake increases calcium excretion in urine, promoting stone formation.

• Balance calcium intake: Contrary to popular belief, adequate dietary calcium (700–1,000 mg daily from food sources) can actually reduce kidney stone risk by binding to oxalate in the gut. Avoid excessive calcium supplements unless prescribed by your doctor.

• Limit oxalate-rich foods: If you have a history of calcium oxalate stones, moderate your intake of high-oxalate foods such as spinach, rhubarb, beetroot, chocolate, and nuts. When consuming these foods, pair them with calcium-containing foods to reduce oxalate absorption.

• Reduce animal protein: Excessive consumption of meat, poultry, and fish can increase uric acid levels and reduce urinary citrate, both of which promote stone formation.

• Consider citrate sources: Adding lemon or lime juice to water may help increase urinary citrate, which inhibits stone formation.

• Avoid excessive vitamin C supplements: High-dose vitamin C (>1,000 mg daily) can increase oxalate production.

• Maintain a healthy weight: While Wegovy supports weight loss, the process itself is beneficial for reducing kidney stone risk, as obesity is an independent risk factor.

If you have a personal or family history of kidney stones, discuss this with your prescribing clinician before starting Wegovy. They may recommend additional monitoring or preventive measures tailored to your individual risk profile.

Importantly, as noted in the Wegovy SmPC, persistent vomiting or diarrhoea can lead to dehydration and potentially acute kidney injury. Contact your healthcare provider if you experience these symptoms and cannot maintain adequate fluid intake.

When to Seek Medical Advice

Knowing when to contact your GP or seek urgent medical attention is crucial for anyone taking Wegovy, particularly if symptoms suggest possible kidney stones or complications related to the medication.

Contact your GP or healthcare provider if you experience:

• Persistent or severe abdominal or flank pain that differs from typical Wegovy side effects or does not resolve with simple analgesia

• Blood in your urine (visible or detected on urine testing)

• Difficulty passing urine or a significant decrease in urine output

• Severe or persistent nausea and vomiting that prevents adequate fluid intake or leads to signs of dehydration (dizziness, dry mouth, reduced urine output, dark urine)

• Unexplained fever alongside urinary symptoms or flank pain, which may indicate infection

Seek immediate medical attention (call 999 or attend A&E) if you develop:

• Severe, uncontrollable pain that is not relieved by over-the-counter painkillers

• High fever (above 38°C) with rigors (shaking chills) alongside urinary symptoms, suggesting possible sepsis

• Complete inability to pass urine, which may indicate urinary obstruction

• Signs of severe dehydration, including confusion, rapid heartbeat, or fainting

• Fever with suspected kidney stone obstruction, which requires urgent assessment as per NICE guideline NG118

For non-emergency but urgent concerns, you can also contact NHS 111 for advice.

For routine monitoring while taking Wegovy, your healthcare provider should conduct regular reviews to assess treatment response, side effects, and overall health. According to NICE Technology Appraisal 875, Wegovy is initiated by specialist weight management services in the UK, with monitoring protocols determined by these services. Treatment within NHS settings is typically limited to a maximum of 2 years.

If you have concerns about kidney stones or any other aspect of your treatment with Wegovy, do not hesitate to discuss these with your prescribing clinician or pharmacist. They can provide personalised advice, arrange appropriate investigations (such as urine tests or imaging), and adjust your treatment plan if necessary. Early recognition and management of potential complications ensure the safest and most effective use of Wegovy for weight management.

Frequently Asked Questions