Double Chin Injections: Kybella vs Meso-Fat Blends

What is Kybella, and how does a double chin injection work?

A double chin injection is an injection into the fat layer under the chin to reduce the fat there. The medical term is injection lipolysis. [1][2][3]

The only drug the US FDA has approved for this, in 2015, is deoxycholic acid, sold as Kybella. [2] Its label says the drug destroys the cell membrane of the fat cells it is injected into, so the cells rupture. [1]

In Thai, “fat injection” or “meso-fat” (เมโสแฟต) is a name for several spot fat-dissolving formulas, not the name of one drug. [7] So “fat injection for the chin” could mean the approved drug or a blend that has not been evaluated. Ask your doctor which one is used. [3][7]

Is a double chin caused by fat, loose skin, or chin structure?

A double chin does not always come from fat. An anatomical review says a double chin has several causes that can overlap. [5]

The review groups the main causes into three: present from birth, after jaw or chin surgery, and too much fat under the chin. [5] A chin that projects less lets tissue, including fat, gather under the chin. [5]

The same review also mentions skin that has lost its elasticity, and platysma muscle bands that show as lines along the neck. [5] The most common pattern is linked to weight gain or fat that builds up locally around the neck. [5]

The label of the US FDA-approved drug tells doctors to screen for other causes of a fuller area under the chin before injecting, such as an enlarged thyroid or enlarged lymph nodes in the neck. [1] A physician reviewing serious risks after injection also advises assessing the cause of the fat under the chin before choosing a method. [8]

How does the approved under-chin injection differ from meso-fat blends?

The difference lies in regulatory evaluation and the approved scope, not only in the ingredient name. The US FDA says Kybella and generics of the same drug are the only products approved to improve the look of fat under the chin. [2]

That approval is from the US FDA, not from Thailand. [2] In 2018, Thai FDA (อย.) said it had never registered any fat-dissolving injection product as a drug. [7] Before you decide, ask your doctor whether the product to be used is permitted in Thailand, and check the latest status with Thai FDA.

The approved drug has data from randomized, placebo-controlled trials. In a phase 3 trial published in the British Journal of Dermatology, about 59-65% of people who got the drug were rated by a doctor as improved, compared with 23.0% on placebo. [4] This is an average for the trial group, not a result guaranteed for any one person. [4]

Who may suit a double chin injection, and who should be careful?

The trials of the approved drug enrolled adults aged 19-65 with a body mass index of 40 or less, moderate to severe fat under the chin, and no excessive loose skin. [1]

The British Journal of Dermatology trial excluded people with other causes of a fuller area under the chin and people with a body mass index over 30. [4] So read the trial results as data for people like that, not for everyone. [1][4]

For the cases below, the label or studies call for extra care. A doctor must assess them first, because the cause and the precautions have to be checked for each person. [1][8]

• Infection in the area under the chin: the label says the drug must not be used. [1]
• Current or past trouble swallowing: the label says to avoid it, because the drug may make it worse. [1]
• A bleeding disorder, or taking antiplatelet or anticoagulant drugs: the label says to be careful, because bleeding or bruising may be heavier than usual. [1]
• Very loose skin or clear platysma muscle bands: the label says to weigh the risk, because the result may not be satisfactory. [1]
• Previous surgery or cosmetic procedures under the chin: the label says to use with care, because the anatomy or tissue may have changed. [1]
• Pregnancy: the label says there are not enough trials in pregnant women. [1]
• Allergy to eggs or soy: the authors of the PC-DC study list this as a group needing caution. [6]

What are the risks of double chin injections?

The most common side effects in the trials of the approved drug were swelling, bruising, pain, numbness, redness, and hardness at the injection site. [1] In the same trials, about 77-80% of people given the drug had pain or stinging, about 65-66% swelling, about 54-56% bruising, and about 48-51% numbness. [4]

The label also warns of more serious risks: injury to the marginal mandibular branch of the facial nerve, which can cause an uneven smile or facial muscle weakness; trouble swallowing; skin ulcers or tissue death; lumps or masses under the skin; and infection. [1] The nerve injuries in the trials all resolved on their own. [1]

Some lumps under the skin do not go away and may need medical treatment. [1] The US FDA found 117 reports in which lumps had not resolved, lasting an average of 143 days at the time of the report. [2]

Injecting outside the area under the chin is not approved. The US FDA found 129 reports since 2015, including serious problems such as blurred vision after injection around the eyes, and muscle or nerve injury. [2]

For products that are not approved, the US FDA reports permanent scars, serious infections, deformed skin, cysts, and deep painful lumps. [3] In 2018, Thai FDA warned of severe allergic reactions that can be life-threatening, infections, and wavy-looking skin because many injection points are needed. [7] In a group of patients given the PC-DC formula, 15 had an accidental injection into muscle with severe pain. [6]

Who should do the injection, and what should you ask before deciding?

The injector must be a doctor, and the substance injected must be approved by Thai FDA, according to Thai FDA and the Medical Council of Thailand. [7][9] The label of the approved drug also says a health care professional must inject it. [1]

The US FDA warns against buying fat-dissolving products from websites to inject yourself. [3] The safety of the approved drug depends on the number and sites of injections, needle placement, and correct technique. [1] A review of serious risks after injection also says the injector needs skill and an understanding of the aesthetic goal. [8]

If after treatment you have an uneven smile, facial muscle weakness, trouble swallowing, or a severe skin wound, see a doctor right away. [2]

• Which drug is it? Ask to see the label and the documents that are valid in Thailand. [7]
• Is my double chin from fat, loose skin, or chin structure? [5][8]
• If I have loose skin or neck muscle bands, is another method a better fit? [1][5]
• What are the risks to the nerve and to swallowing, and who do I contact if they happen? [1]
• What health history and medicines should I tell you about, especially anything that makes me bleed easily? [1]

If an injection does not suit you, are there other options?

The anatomical review mentions other options for reducing fat under the chin or lifting the area: liposuction, energy-based devices that reduce fat, fat-dissolving injections, and thread lifts. [5]

For older adults with very loose neck skin, that review says surgery is often needed. [5] The authors of the PC-DC study also say fat-dissolving injections can be an add-on but do not replace surgical liposuction. [6]

For fat loss in general, Thai FDA advises focusing on exercise and diet control. [7] Which method to choose should come after a doctor assesses the cause of your double chin. [8]