Saxenda (liraglutide 3.0 mg) is a prescription weight management medicine that can cause various side effects, particularly affecting the digestive system. Understanding the side effects of Saxenda is essential for anyone considering or currently using this GLP-1 receptor agonist medication. Whilst most adverse effects are mild and temporary, some require immediate medical attention. This article provides comprehensive guidance on common and serious side effects, practical management strategies, and important safety information aligned with UK clinical guidance from NICE, the MHRA, and the product licence to help patients and healthcare professionals make informed decisions about Saxenda treatment.

What Is Saxenda and How Does It Work?

Saxenda (liraglutide 3.0 mg) is a prescription medicine licensed in the UK for weight management in adults with a BMI ≥30 kg/m² (obesity) 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 were originally developed for treating type 2 diabetes. Saxenda is administered as a once-daily subcutaneous injection, typically into the abdomen, thigh, or upper arm.

The medication works by mimicking the action of GLP-1, a naturally occurring hormone that regulates appetite and food intake. When injected, liraglutide activates GLP-1 receptors in the brain, particularly in areas that control hunger and satiety. This leads to reduced appetite, increased feelings of fullness after eating, and consequently lower calorie intake. Additionally, Saxenda slows gastric emptying, meaning food remains in the stomach longer, which further contributes to prolonged satiety.

According to NICE technology appraisal guidance (TA664), Saxenda should be used alongside a reduced-calorie diet and increased physical activity as part of a comprehensive weight management programme. The medication is typically prescribed within specialist weight management services when lifestyle interventions alone have not achieved adequate weight loss. Treatment should be discontinued if patients do not lose at least 5% of their initial body weight after 12 weeks at the full maintenance dose (3.0 mg daily), as specified in the product licence.

It is important to understand that Saxenda is not a quick fix for weight loss. The medication requires commitment to dietary and lifestyle changes, and its effects are most pronounced when combined with behavioural modifications. Patients should have realistic expectations about weight loss outcomes and be aware of potential side effects before starting treatment.

Common Side Effects of Saxenda

The majority of people taking Saxenda will experience some side effects, particularly during the initial weeks of treatment. Gastrointestinal symptoms are by far the most frequently reported adverse effects, affecting a significant proportion of users. According to the UK product information, these include:

• Nausea – the most common side effect, experienced by approximately 40% of patients, usually most pronounced during dose escalation

• Diarrhoea – affects around 20% of users and typically improves over time

• Constipation – occurs in approximately 20% of patients

• Vomiting – reported by roughly 16% of users

• Abdominal pain or discomfort – experienced by about 10-15% of patients

• Indigestion and flatulence – relatively common but usually mild

These gastrointestinal effects occur because Saxenda slows the movement of food through the digestive system and affects gut motility. Most symptoms are mild to moderate in intensity and tend to diminish as the body adjusts to the medication, typically within the first few weeks. The gradual dose escalation schedule (starting at 0.6 mg daily and increasing weekly) is specifically designed to minimise these effects.

Other common side effects include injection site reactions such as redness, itching, or bruising where the needle enters the skin. Some patients report headaches, particularly in the early stages of treatment. Fatigue and dizziness may also occur, though these are generally transient.

Saxenda can cause a small increase in heart rate. Contact your healthcare provider if you experience persistent palpitations or unusually rapid heartbeat.

Hypoglycaemia (low blood sugar) is primarily a risk for people with diabetes who are also taking insulin or sulfonylureas. For those without diabetes, the risk is low. Symptoms include shakiness, sweating, confusion, and rapid heartbeat. If you have diabetes, your doctor may need to adjust your other medications when starting Saxenda.

Serious Side Effects and When to Seek Medical Help

While most side effects of Saxenda are manageable, certain serious adverse reactions require immediate medical attention. Patients and healthcare professionals should be vigilant for the following:

Pancreatitis (inflammation of the pancreas) is a rare but serious risk associated with GLP-1 receptor agonists. Warning signs include severe, persistent abdominal pain that may radiate to the back, often accompanied by nausea and vomiting. This pain typically does not improve with standard remedies. If suspected, patients should stop taking Saxenda immediately and seek urgent medical assessment. The MHRA has highlighted this risk, and the medication should not be restarted if pancreatitis is confirmed.

Gallbladder problems, including gallstones (cholelithiasis) and inflammation (cholecystitis), occur more frequently in people losing weight rapidly. Symptoms include sudden, severe pain in the upper right abdomen, pain between the shoulder blades, yellowing of the skin or eyes (jaundice), and fever. These symptoms warrant prompt medical evaluation.

Acute kidney injury has been reported, particularly in patients who experience severe vomiting and diarrhoea leading to dehydration. Warning signs include significantly reduced urine output, swelling in the legs or feet, unusual tiredness, and confusion. Patients should maintain adequate hydration and contact their GP if they cannot keep fluids down.

Severe allergic reactions (anaphylaxis), though rare, can occur. Symptoms include difficulty breathing, swelling of the face, lips, tongue or throat, severe rash, and rapid heartbeat. This is a medical emergency requiring immediate 999 call.

In animal studies, liraglutide caused thyroid C-cell tumours, though a causal relationship in humans has not been established. Nevertheless, patients should report any lump or swelling in the neck, hoarseness, difficulty swallowing, or persistent cough to their doctor.

For people with diabetes using insulin, rapid reduction in insulin doses when starting Saxenda may increase the risk of diabetic ketoacidosis. Insulin adjustments should be made gradually under medical supervision.

Patients experiencing persistent or severe symptoms, significant changes in mood, or any concerns about their medication should contact their GP or healthcare provider without delay. Suspected side effects can be reported via the MHRA Yellow Card Scheme.

Managing Side Effects While Taking Saxenda

Effective management of side effects can significantly improve treatment adherence and outcomes. The following evidence-based strategies can help minimise discomfort:

For gastrointestinal symptoms:

• Eat smaller, more frequent meals rather than large portions, which can overwhelm the slowed digestive system

• Avoid high-fat, greasy, or spicy foods that may exacerbate nausea and indigestion

• Stay well hydrated by sipping water throughout the day, particularly important if experiencing vomiting or diarrhoea

• Eat slowly and chew thoroughly to aid digestion and reduce bloating

• Some patients find ginger tea or peppermint helpful for nausea relief, though evidence for these remedies is limited

• Take the injection at a consistent time each day, preferably when nausea is typically less problematic

For injection site reactions:

• Rotate injection sites systematically to prevent irritation in any one area

• Ensure the medication has reached room temperature before injecting (remove from refrigerator 30 minutes beforehand)

• Use proper injection technique as demonstrated by your healthcare provider

• Apply a cold compress after injection if redness or swelling occurs

General management approaches:

• Follow the gradual dose escalation schedule precisely – do not rush to increase the dose, as this significantly increases side effects

• If gastrointestinal symptoms are persistent and troublesome, your healthcare provider may recommend temporarily maintaining a lower dose or slowing the titration schedule

• Keep a symptom diary to identify patterns and triggers

• Maintain regular contact with your prescribing healthcare professional, who may adjust the dose or provide additional support

• Ensure adequate fibre intake if experiencing constipation, and discuss laxatives with your pharmacist if needed

If side effects become intolerable despite these measures, consult your GP. They may recommend temporarily reducing the dose, pausing treatment, or considering alternative weight management strategies. According to NICE guidance, treatment should be individualised, and the benefits must outweigh the adverse effects for continuation to be appropriate. It is safe to stop Saxenda if you experience severe side effects, but do not restart without medical advice. Do not share your medication with others, even if they have similar weight management goals.

Who Should Not Use Saxenda?

Saxenda is not suitable for everyone, and certain individuals should not use this medication due to safety concerns. Healthcare professionals must carefully screen patients before prescribing.

According to the UK product licence, Saxenda must not be used in:

• People with hypersensitivity (allergy) to liraglutide or any ingredients in the formulation

• Pregnant women – weight loss during pregnancy may harm the developing baby

Saxenda is not recommended during breastfeeding as it is unknown whether liraglutide passes into human milk or what effect it might have on the infant.

Conditions requiring careful assessment and monitoring:

• History of pancreatitis – the risk-benefit ratio must be carefully considered

• Inflammatory bowel disease or diabetic gastroparesis – Saxenda slows gastric emptying and may worsen these conditions

• Severe renal or hepatic impairment – limited data exist for these populations, and dehydration may increase kidney injury risk

• Heart failure – particularly NYHA class III-IV, as experience is limited

• History of depression or suicidal thoughts – mood changes have been reported, though a causal relationship has not been established

• Elderly patients over 75 years – limited clinical experience in this age group

• Personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2 – animal studies showed thyroid tumours; human relevance is unknown

Patients taking certain medications require special consideration. Those on insulin or sulfonylureas may need dose adjustments to prevent hypoglycaemia. While Saxenda may theoretically affect the absorption of oral medications due to delayed gastric emptying, this rarely causes clinically significant interactions. However, patients taking warfarin or other coumarins should have their INR monitored when starting Saxenda.

Before starting Saxenda, healthcare professionals should conduct a comprehensive assessment including medical history, current medications, and discussion of realistic weight loss expectations. According to NICE guidance (TA664), Saxenda should only be prescribed as part of a specialist weight management service with appropriate multidisciplinary support. Patients must be committed to lifestyle changes and understand that medication alone is insufficient for sustainable weight management. Regular monitoring and review are essential to ensure ongoing safety and effectiveness.

Frequently Asked Questions