Fat Dissolving Injections: What Is Deoxycholic Acid, Which Area Is It Approved For, and How Many Sessions Are Needed?

What is a fat-dissolving injection and how does it work?

Deoxycholic acid is a substance that occurs naturally in the body in bile and helps to digest the fat taken in with food. When injected into the fat tissue under the skin, it disrupts the membrane of the fat cells and breaks the cells down. The remains of the broken-down cells are cleared by the body over weeks. In medical language this procedure is called injection lipolysis.

The substance does not distinguish fat cells from the surrounding tissue; it can also damage skin, muscle or nerve that it comes into contact with. For this reason the line between effect and side effect is a fine one, and where and at what depth the product is placed is decisive. The marked swelling seen after the procedure is likewise not a mishap but the expected result of the inflammatory reaction in the fat tissue.

A fat-dissolving injection is not a weight-loss method. It does not change the weight on the scales, fat inside the abdomen or weight-related health risks; it targets only the appearance of fat under the skin in a limited area.

Which area is it approved for? What about the abdomen, waist and arms?

In 2015 the US Food and Drug Administration (FDA) approved the injection whose active substance is deoxycholic acid for improving the appearance of moderate or marked fullness due to fat under the chin in adults. The FDA's page for consumers states plainly that the medicine has been evaluated only for under the chin and is not approved for any other area of the body. The official prescribing information also states that its use for fat under the skin outside the area under the chin is not recommended.

In 2026 the FDA strengthened this warning: because serious events such as blurred vision and muscle and nerve damage were reported after the medicine was used outside the area under the chin, for example around the eyes, an additional warning was added to the prescribing information. Treatments to areas such as the cheeks, jawline, under-eye bags, armpits, abdomen or above the knees therefore fall outside the approved use; in these areas the balance of benefit and harm has not been studied to the same standard.

Which product is licensed for which purpose in Turkey is a separate matter and may change. Ask your physician for the name, active substance and licensing status of the product to be used on you.

Phosphatidylcholine mixtures and lipolysis mesotherapy: what does the evidence say?

For many years, mixtures containing phosphatidylcholine (a fat component derived from soya) have also been injected in order to dissolve fat. These mixtures also contain deoxycholate, which keeps the phosphatidylcholine in solution. A review of these treatments reports that there are publications describing a reduction in small fat deposits, and that the breakdown of cells is attributed largely to the detergent effect of the deoxycholate in the mixture. The same review emphasises that the claim that other substances used in classic mesotherapy reduce fat is not supported by peer-reviewed studies, and that the safety and effectiveness of these treatments remain uncertain.

The FDA's consumer warning points the same way: injections containing phosphatidylcholine and sodium deoxycholate, used alone or together, are not approved; that is, their safety and effectiveness have not been evaluated by the FDA. The agency has announced that scarring, serious infection, skin deformity, cysts and deep, painful nodules have been reported after these products, and that some of the reports came from people who bought the product online and injected themselves.

In treatments offered under names such as lipolysis mesotherapy, fat-burning cocktail and the like, the content is usually not a single substance but a mixture, and what the mixture contains is not always disclosed. The evidence is limited: there are no studies, of the standard available for the approved medicine, showing which mixture works in what amount and in which area, and how safe it is. A general account of mesotherapy is given in the article “Mesotherapy”, and the problems that can be seen after injection in the article “Problems after Mesotherapy”.

Who may it be suitable for?

• Adults with moderate or marked fullness due to fat under the skin beneath the chin that can be grasped by hand
• People whose skin is sufficiently elastic, that is, whose skin is expected to retract once the fat has decreased
• People whose weight has been stable for some time and who know that the result will appear gradually, over several sessions
• People who are able to accept living with marked swelling in the days after the procedure

Not all fullness under the chin is fat. The prescribing information requires other causes, such as enlargement of the thyroid gland and of the lymph nodes in the neck, to be investigated before treatment. The causes of the fullness, and which method is considered in which situation, are explained in detail in the article “Double Chin (Submental Fullness)”.

Who is it not suitable for, and what should you watch out for?

• Infection in the treatment area: according to the prescribing information, treatment is not given in this situation.
• Difficulty swallowing, or a past history of difficulty swallowing: the procedure may make this problem worse.
• Marked skin laxity or prominent muscle bands in the neck: when the fat decreases, the laxity and bands may become more visible.
• A bleeding disorder or use of blood-thinning medicines: bruising and bleeding may increase. Do not stop your medicine on your own; talk to your physician.
• Previous surgery or an aesthetic procedure under the chin or on the neck: the anatomy may have changed; the physician needs to know this.
• Pregnancy and breastfeeding: there are not enough safety data; the procedure is postponed.
• People under 18: the prescribing information does not recommend its use in children and adolescents.
• People who want to lose weight in general: this method does not serve that purpose.

This list is not complete. Tell your physician about all your medical conditions and the medicines and supplements you take. For pregnancy and breastfeeding, see the article “Medical Aesthetics in Pregnancy and Breastfeeding”.

Who should perform it, and where?

A fine nerve branch that moves the lower lip runs along the lower edge of the jawbone, and under the chin there are salivary glands, lymph nodes and blood vessels. The official prescribing information requires the treatment to be given only by healthcare professionals and a specific technique to be followed in order to stay away from these structures. For this reason the procedure needs to be performed in a healthcare facility by a physician who knows the anatomy of the neck and can make an assessment if a problem arises.

Ask for the product to be opened in front of you from its sealed, original packaging. Do not accept mixtures whose content is not disclosed on the grounds that it is a 'special formula', products bought online, or treatments carried out in places such as homes, hotel rooms or beauty salons. The warning signs on this subject are explained in the articles “Counterfeit Products and Unlicensed Treatments” and “Group Aesthetic Treatments at Home and in Hotels”.

Preparing for the procedure

• During the examination it is assessed whether the fullness under the chin is due to fat, to skin laxity or to another cause; the physician examines the area by hand.
• Mention all the medicines you take, any tendency to bleed, and any existing problems with swallowing or facial movements.
• Report any previous surgery, liposuction, filler or other procedures in the area.
• Because the swelling may be marked for days, do not schedule the procedure just before an important event, meeting or photo shoot.
• Discuss in advance how many sessions are anticipated and when the result will be assessed.
• Read the consent form without hurrying; ask about anything you do not understand.

The day of the procedure, step by step

1. Your medical history and expectations are reviewed; the informed consent form is read and signed. Photographs are usually taken for the record.
2. The physician examines the area under the chin by hand to identify the fat tissue and the areas to be avoided, and marks the treatment area on the skin.
3. The skin is cleaned with an antiseptic solution. Cold application, a numbing cream or local anaesthesia may be used to reduce discomfort.
4. The medicine is injected with a fine needle into the fat tissue under the skin, in small amounts at the marked points. The number of injections is determined by the distribution of the fat.
5. During and immediately after the injections there is a burning, stinging and warm sensation; the procedure is not free of pain. This sensation usually lessens within a short time.
6. If necessary, pressure is applied briefly to the needle sites. Aftercare advice and details of how to reach the physician are given; you can go home the same day.

After the procedure: the first 24 hours, the first week, the first month

• First 24 hours: swelling, redness, warmth, pain and numbness begin. You may apply cold if your physician has recommended it, and in the way recommended. Do not massage or press on the area.
• First week: the swelling is at its most marked in the first days, and the area under the chin may look fuller than before the procedure. Bruises begin to fade. If you notice difficulty swallowing or an asymmetric smile, tell your physician the same day.
• First month: the swelling gradually goes down; numbness and palpable firmness may last for weeks. The result is not assessed during this period. The decision on the next session is made by examination.

How long does the swelling last? Expected side effects

With this procedure swelling is not the exception but the rule. In the approval studies of the medicine, swelling was reported in about nine in ten of the people injected, bruising in nearly three quarters and numbness in two thirds. Pain, redness and firmness in the area are also common effects.

The rates in the table are rounded from the clinical trial data in the US prescribing information and apply to treatments under the chin with the approved product. There are no similar data for other mixtures and other areas. In most people the swelling peaks in the first days and goes down over weeks; although it is reported to be generally milder in later sessions, this varies from person to person.

Less commonly, an asymmetric smile due to an effect on the nerve that moves the lower lip, difficulty swallowing, hair loss in the area, skin ulceration, persistent nodules and infection may occur. We do not go into these problems in detail here; which is expected and which is an emergency, and what to do and not to do at home, are explained in the article “Problems after Fat-Dissolving Injections and Mesotherapy”.

How many sessions are needed, and when is the result seen?

According to the US prescribing information, a maximum of six sessions can be given, with at least one month left between sessions; the number of sessions and injections is determined by the person's fat distribution and aim. A marked change should not be expected from a single session. In a large placebo-controlled study, an improvement of one grade on the physician's assessment was seen in about half of the participants after two sessions and in three quarters after four sessions.

In the same study, twelve weeks after the last session an improvement of at least one grade on both the physician's and the patient's assessment was found in about seven in ten of those given the medicine and in fewer than one in five of those given placebo. A marked improvement of two grades was seen in about one in seven of those given the medicine. In other words, most people see some improvement, while a striking change remains in the minority. New fat cells are not expected to replace those that have been broken down; however, if weight is gained the fat cells remaining in the area can enlarge, and the skin can loosen with age.

Realistic expectations: what can fat-dissolving injections not do?

• They do not cause weight loss; no change on the scales should be expected.
• They do not tighten loose skin; when the fat decreases, laxity may become more visible.
• They do not change deep fat beneath the muscle, an enlarged salivary gland or an appearance due to a receding jawbone.
• They do not give a result in a single session; the result is assessed after the swelling has gone down and the sessions have been completed.
• They do not improve the appearance of cellulite.
• They do not give the same result in everyone; no promise can be made about the result.

Alternatives

The use of these options under the chin is compared in the article “Double Chin (Submental Fullness)”, and the method of reducing fat by cooling in the article “Cryolipolysis (Fat Reduction by Cooling)”.

This content is for information purposes; it does not replace an examination. The method that suits you can only be determined by a physician's assessment.