Saxenda (liraglutide 3.0 mg) is a GLP-1 receptor agonist administered as a daily subcutaneous injection for weight management in adults and adolescents meeting specific BMI criteria. Some patients notice small lumps, bumps, or bubble-like swellings under the skin at injection sites. These localised reactions may result from inflammation, fluid accumulation, or lipohypertrophy (fatty tissue build-up) caused by repeated injections. Whilst most injection site reactions are mild and self-limiting, understanding their causes and prevention strategies is essential for treatment adherence and optimal medication absorption. Persistent, painful, or enlarging lumps require medical review to exclude infection or other complications.

Understanding Subcutaneous Injection Lumps with Saxenda

Saxenda (liraglutide 3.0 mg) is a glucagon-like peptide-1 (GLP-1) receptor agonist licensed in the UK for weight management in adults with a body mass index (BMI) of 30 kg/m² or greater, or 27 kg/m² or greater in the presence of weight-related comorbidities. It is also licensed for adolescents aged 12 to <18 years with obesity and body weight above a specified threshold. Administered as a once-daily subcutaneous injection, Saxenda works by mimicking the action of the naturally occurring hormone GLP-1, which regulates appetite and food intake through effects on the brain's satiety centres.

When injecting Saxenda into the subcutaneous tissue—the layer of fat beneath the skin—some patients may notice the development of small lumps, bumps, or what appears as a "bubble" under the skin at the injection site. These localised reactions can represent inflammation or fluid accumulation at the injection site. With repeated injections in the same area, lipohypertrophy (a build-up of fatty tissue) may also occur. The subcutaneous route is chosen specifically because it allows for gradual absorption of the medication into the bloodstream, but this process can occasionally trigger visible tissue changes.

According to the Saxenda Summary of Product Characteristics (SmPC), injection site reactions are generally mild and transient, typically resolving without medical intervention within days. However, understanding why these lumps occur and how to minimise their occurrence is important for patient comfort, treatment adherence, and optimal medication absorption. Persistent, painful, or enlarging lumps warrant medical review, as do any signs of infection such as increasing redness, warmth, or discharge. The formation of subcutaneous lumps does not necessarily indicate improper injection technique, though technique optimisation can significantly reduce their frequency and severity.

Common Causes of Bubbles or Lumps After Saxenda Injection

Several mechanisms can lead to the development of palpable lumps or bubble-like swellings following Saxenda administration. Lipohypertrophy can occur with repeated injections in the same site—this is an abnormal accumulation of subcutaneous fat that develops when the same injection areas are used too frequently. The repeated trauma and medication exposure can stimulate localised fat cell proliferation, creating firm, rubbery lumps that may persist for months. Lipohypertrophy not only causes cosmetic concern but can also impair medication absorption, potentially reducing Saxenda's efficacy.

Localised inflammatory reactions constitute another common cause. The injection process itself causes minor tissue trauma, and some individuals mount a more pronounced inflammatory response to either the liraglutide molecule or the formulation excipients. This typically manifests as temporary swelling, redness, and a soft, fluid-filled sensation under the skin that may resemble a bubble. These reactions usually resolve gradually over several days.

Improper injection technique can contribute significantly to lump formation. Injecting too superficially (into the dermis rather than subcutaneous tissue) or too deeply (into muscle) can cause localised reactions. Bruising and haematoma formation may occur if a small blood vessel is inadvertently punctured during injection, creating a raised, tender area that may initially appear bubble-like.

Rarely, true allergic reactions to Saxenda components can cause urticarial wheals or angioedema at injection sites. These typically appear rapidly after injection, are often itchy, and may be accompanied by other allergic symptoms. Any suspected allergic reaction requires prompt medical assessment. If you experience severe allergic symptoms such as difficulty breathing or facial swelling, call 999 immediately. For urgent but non-emergency concerns, contact NHS 111.

How to Prevent Injection Site Reactions with Saxenda

Preventing subcutaneous lumps and bubbles requires attention to proper injection technique and systematic site rotation. Site rotation is paramount—the abdomen, thighs, and upper arms are all approved injection sites for Saxenda, and patients should rotate between these areas and within each area systematically. Avoid injecting into the exact same spot repeatedly and do not inject into areas of lipohypertrophy, scar tissue, or skin abnormalities. This practice significantly reduces the risk of lipohypertrophy and allows tissue adequate recovery time between injections. Note that upper arm injections may be easier if given by another person.

Proper injection technique begins with allowing Saxenda to reach room temperature before injection, as cold medication is more likely to cause discomfort. Patients should wash hands thoroughly and cleanse the injection site with an alcohol wipe if needed, allowing the skin to dry completely before injection. The skin should be pinched gently to elevate subcutaneous tissue, and the needle inserted at a 90-degree angle (or 45 degrees for very lean individuals) in a swift, confident motion. After depressing the injection button fully, the needle should remain in place for at least 6 seconds to ensure complete medication delivery and prevent leakage, as directed in the Saxenda Instructions for Use.

Needle hygiene and replacement are essential—Saxenda pen needles are designed for single use only and should never be reused or shared with others. Reusing needles increases infection risk, causes more tissue trauma, and may result in inaccurate dosing. Before first use of a new pen, perform a flow check as directed in the Instructions for Use. Never store the pen with a needle attached.

Proper disposal of used needles is important for safety. Always dispose of used needles in a designated sharps bin and follow local arrangements for sharps disposal. Patients experiencing persistent problems should consult their GP or practice nurse for technique review and personalised advice.

Managing and Treating Subcutaneous Lumps from Saxenda

Most subcutaneous lumps associated with Saxenda resolve spontaneously without specific treatment, but several strategies can facilitate resolution and provide symptomatic relief. For acute, inflammatory-type reactions presenting as soft, tender swellings within hours of injection, conservative management is usually appropriate. Applying a cool compress to the affected area for 10–15 minutes several times daily can reduce inflammation and discomfort. Over-the-counter oral antihistamines may help if itching is present, though patients should consult a pharmacist regarding suitability and potential interactions with other medications.

Lipohypertrophic lumps require a different approach focused on strict site avoidance and time. These firm, rubbery areas should not be used for further injections, as medication absorption from lipohypertrophic tissue is unpredictable and often reduced. With consistent avoidance, lipohypertrophy may gradually diminish over months, though complete resolution is not guaranteed. Avoid massaging injection sites or areas of lipohypertrophy as this may affect medication absorption.

When to seek medical advice is an important consideration. Patients should contact their GP or prescribing clinician if lumps are accompanied by:

• Increasing pain, redness, or warmth suggesting possible infection (cellulitis or abscess)

• Discharge or oozing from the injection site

• Lumps that persist beyond 2–3 weeks or continue enlarging

• Systemic symptoms such as fever, malaise, or feeling generally unwell

For severe allergic symptoms including facial swelling, widespread rash, or breathing difficulties, call 999 immediately. For urgent but non-emergency concerns, contact NHS 111.

For confirmed injection site infections, antibiotic therapy may be necessary. Persistent problematic reactions may prompt review of Saxenda suitability or consideration of alternative weight management strategies. Healthcare professionals can provide technique assessment, demonstrate optimal injection methods, and ensure patients feel confident managing their treatment. Documentation of injection sites and any reactions in a diary can help identify patterns and inform discussions with clinicians, supporting individualised management approaches that optimise both treatment efficacy and patient comfort.

Patients are encouraged to report suspected side effects of Saxenda via the MHRA Yellow Card Scheme at yellowcard.mhra.gov.uk or through the Yellow Card app.

Frequently Asked Questions