Understanding Fat Dissolving Injections

Last updated: 9 August 2026

Fat dissolving injections, also known as injection lipolysis, have become an increasingly popular non-surgical option for reducing localised fat deposits. Using injectable compounds that destroy fat cells, these treatments offer targeted body contouring without surgery. This guide examines how they work, what to expect, and who is a suitable candidate.

How fat dissolving injections work

The primary active ingredient in most fat dissolving injections is deoxycholic acid (also known as desoxycholic acid or sodium deoxycholate). This is a naturally occurring bile acid produced by the liver that plays a role in dietary fat absorption and metabolism. When injected directly into subcutaneous fat deposits, deoxycholic acid disrupts the fat cell membrane, causing the cell to lyse (burst) and release its lipid contents. The released fat and cellular debris are then processed by the body’s lymphatic and metabolic systems over the following weeks.

The key biological process is permanent, once a fat cell is destroyed, it does not regenerate. This means that results from fat dissolving injections are long-lasting, provided the patient keeps a stable weight.

Available Products in the UK

Aqualyx

Aqualyx is the most widely used fat dissolving product in the UK and Europe. It contains deoxycholic acid in a buffered phosphatidylcholine solution, designed to enhance fat cell disruption. Aqualyx has CE marking and has been used in clinical practice since 2009.

Belkyra / Kybella

Belkyra (known as Kybella in the US) is a synthetic deoxycholic acid product that has both FDA approval and CE marking specifically for the treatment of submental (under-chin) fat. It is the most extensively studied fat dissolving product, with Phase III clinical trials involving over 1,600 patients.

6% in the placebo group after two treatment sessions.

Common treatment areas

Submental fat (double chin)

This is the most popular and best-studied indication. The submental area is well-suited because it contains a relatively isolated pocket of fat that responds predictably to treatment. Most patients require 2-4 treatment sessions spaced 6-8 weeks apart.

Other Areas

Fat dissolving injections are also used off-label for:

• Jowl area fat deposits
• Upper arms (bingo wings)
• Flanks (love handles)
• Inner thighs
• Bra fat
• Upper back fat
• Small abdominal fat pockets

“It is crucial to understand that fat dissolving injections are for localised, stubborn fat deposits, not for weight loss or widespread body fat reduction,” emphasises Dr Blake. “The ideal candidate has a specific pocket of fat that is resistant to diet and exercise, is close to their ideal body weight, and has reasonable skin elasticity in the treatment area.”

The treatment process

Consultation

A thorough consultation includes assessment of the fat deposit (pinch test to confirm adequate subcutaneous fat), discussion of realistic expectations, review of medical history, and sometimes photographic documentation.

Treatment Day

1. The area is marked with a grid pattern to ensure even distribution
2. Topical anaesthetic may be applied (though most products contain lidocaine)
3. Multiple small injections are administered into the subcutaneous fat layer
4. For the submental area, typically 10-20 injection points per session
5. Treatment takes approximately 15-30 minutes

Post-Treatment

Significant swelling is expected and normal, this is part of the treatment mechanism. Patients should be prepared for:

• Swelling: Moderate to significant, peaking at 48-72 hours and lasting 1-3 weeks
• Tenderness: The area will feel sore and bruised for 1-2 weeks
• Numbness: Temporary numbness of the treated area, typically resolving within 4-6 weeks
• Firmness: The area may feel hard or nodular as fat cells are processed
• Bruising: Common but usually mild, resolving within 1-2 weeks

Expected results and timeline

Results are not immediate, the body takes 4-8 weeks to process the destroyed fat cells. Most patients see noticeable improvement 6-8 weeks after each session. A course of 2-4 sessions (sometimes more for larger areas) is typically required for optimal results.

Full results are usually visible 3-4 months after the final treatment session, once all inflammation has resolved and the body has completed fat metabolism.

Who is not a suitable candidate?

• Patients with significant excess skin that would sag after fat reduction
• Those expecting weight loss (this is a contouring treatment, not a weight loss tool)
• Patients with infection or skin conditions in the treatment area
• Pregnant or breastfeeding women
• Patients with dysphagia (difficulty swallowing) for submental treatment
• Those with very large fat deposits better suited to liposuction

Risks and Complications

Whilst fat dissolving injections have a generally good safety profile, potential complications include:

• Skin irregularities or indentation if product is placed too superficially
• Prolonged swelling or nodule formation
• Skin necrosis (extremely rare, typically from incorrect injection depth)
• Asymmetric results requiring touch-up treatment

Frequently asked questions

How many sessions of fat dissolving injections do I need?

Most patients require 2-4 sessions spaced 6-8 weeks apart for the submental area, with some needing up to 6 sessions for larger deposits. Your practitioner will assess your specific fat deposit and provide a realistic estimate during consultation. Each session produces incremental improvement.

Are the results of fat dissolving injections permanent?

Yes, the fat cells destroyed by the treatment do not regenerate. However, remaining fat cells in the area can enlarge with significant weight gain, potentially diminishing results. Maintaining a stable weight through balanced diet and regular exercise is important for preserving results long-term.

How painful is the treatment?

Most patients describe the injections as moderately uncomfortable, a stinging or burning sensation during and immediately after injection. This typically subsides within 10-15 minutes. Some products contain lidocaine to reduce discomfort. The post-treatment soreness resembles a mild bruise and is manageable with standard pain relief.

How does fat dissolving compare to liposuction?

Fat dissolving injections are best for small, localised fat deposits and involve no surgery, no general anaesthesia, and minimal downtime. Liposuction is more effective for larger fat volumes, provides immediate results, and offers more precise contouring. However, liposuction is a surgical procedure with associated risks and recovery time. Your practitioner can advise which approach is most appropriate for your specific concern.