If I develop mouth corner asymmetry, will it last a lifetime?

For the most part, this is only temporary. The nerve has not been severed but merely irritated, so it typically recovers within a few weeks to a few months. Permanent damage is extremely rare.

Can nerve damage be 100% prevented?

While we can significantly reduce the risks, it is difficult to declare them as absolute zero. The most important preventive measure is to clearly understand the anatomy and administer small amounts precisely within the safe zones.

Since the formula is designed to cause minimal swelling, is it also safe for the nerves?

Ingredients that cause minimal swelling and irritation can be beneficial for recovery. However, the risk of nerve damage depends much more on the precise location and depth of the injection rather than the ingredients themselves. The practitioner's precision is the key.

Is corner of the mouth asymmetry visible even when the face is at rest?

It is often barely noticeable while your face is at rest, but becomes more apparent when you smile. When smiling, one corner of your mouth may not lower as usual, making your expression look slightly asymmetrical. This is usually temporary and tends to resolve on its own over time.

Crooked Smile After Fat Injections—Permanent?|Hongdae Seoul Clinic

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Crooked Smile After Fat Injections—Permanent?

Nerve effects from fat injections are usually temporary—symptoms, recovery, safe care.

Jun 7, 2026

📚 Deconstructing Fat Dissolving Injections · Series Table of Contents

1. What are Fat Dissolving Injections?
- 1.1 Principles & Difference from Contour Injections
2. Ingredients & Products
- 2.1 DCA V-Olet
- 2.2 Cholic Acid NewViju · Double Slim
3. Side Effects & Safety
- 3.1 Temporary Nerve Damage (Current Article)
- 3.2 Common Reactions & Safety
4. Making a Choice
- 4.1 Product Selection Guide

When researching fat dissolving injections, you might come across scary stories like, "My nerve was damaged, and the corner of my mouth became paralyzed." It is completely understandable why many hesitate to get the treatment, even if the results are highly effective.

First, let us reassure you. These nerve symptoms are rare, and even if they do occur, most are temporary and resolve on their own over time. However, it is always best to understand why they happen and how to minimize the risks before getting treated.

Quick AnswerAsymmetry at the corner of the mouth after fat-dissolving injections is rare. It is typically caused by temporary irritation of the nerve and usually recovers within a few weeks to a few months. Permanent damage is extremely rare.

Why are nerves affected?

Underneath the jawline runs the marginal mandibular nerve*. This nerve is responsible for controlling the muscles that pull the corners of your mouth downward.

* Marginal Mandibular Nerve: One of the branches of the facial nerve. It runs along the jawline and controls the muscles that pull down the corners of the mouth. It is a critical nerve that requires careful attention during double chin treatments.

Since fat dissolving injections target and break down submental fat under the chin, the nerve can become temporarily irritated if the product diffuses close to it or is injected too deeply. This does not mean the nerve is severed; rather, temporary swelling and contact with the product can briefly slow down its function. Since the marginal mandibular nerve is a branch of the facial nerve* which controls expression, any irritation can temporarily affect part of your facial expressions.

* Facial Nerve: The nerve responsible for moving the muscles of facial expression. It branches out into several pathways, and the branch passing along the jawline is involved in the movement of the corners of the mouth.

This is why the submental area requires extra precision compared to other treatment sites. It is not just about injecting wherever there is fat; we must carefully steer clear of the nerve pathways.

What symptoms might occur?

The most common presentation is asymmetry at the corners of the mouth. When you smile, one side of your mouth may not pull down as naturally as usual, making your expression look slightly uneven. This is often barely noticeable when your face is at rest, but becomes visible when you smile.

In rare cases, you might experience temporary discomfort when swallowing along with swelling. Some mild numbness or a tingling sensation can also occur.

The most important thing to remember is that these symptoms do not happen to everyone. They are not common occurrences, and having a treatment designed with precise anatomical knowledge in a designated "safe zone" significantly minimizes the likelihood of encountering them.

Remember, "temporary" is the key word

The question that worries most people is, "Is this permanent?" We can confidently reassure you that almost all cases are temporary.

Because the nerve is merely compressed or mildly irritated rather than severed, your facial movement will naturally return to normal once the swelling subsides and the nerve recovers. In most cases, you will see improvement within a few weeks to a few months. Permanent side effects are exceptionally rare.

Symptom	Typical Progression
Asymmetry of the mouth corner	In most cases, resolves within a few weeks to months
Swallowing discomfort	Improves as the swelling goes down
Numbness / Tingling	Gradually returns to normal

We understand that an uneven expression during the recovery period can be distressing. That is why being aware of these possibilities beforehand is so essential. Experiencing this without prior notice can be startling. If your symptoms are prolonged or severe, we recommend reaching out to your clinic for an accurate, professional consultation.

Minimizing risks — It is about technique, not just ingredients

This is a point we really want to emphasize: protecting the nerves has much more to do with the injection technique than the ingredients used.

Anatomical Precision: Injecting strictly within the designated safe zones, bypassing the pathways of the marginal mandibular nerve. This is paramount.
Optimal Depth: Ensuring the product remains strictly in the subcutaneous fat layer, without going too deep.
Micro-droplet Distribution: Splitting the dose and administering small amounts evenly rather than injecting a large pool in one spot.

Using formulations with low swelling and irritation, such as cholic acid or anti-inflammatory blends, can certainly support a smoother recovery environment. However, the risk to the nerves is not reduced to zero by product selection alone; it is decided by 'who' injects 'where' and at 'what depth'. Therefore, the most reliable way to prevent side effects is to choose a clinic with deep expertise in submental anatomy. Rather than choosing based on results alone, make sure you trust the medical hands performing your treatment.

Frequently Asked Questions

Q. If my smile becomes asymmetrical, will it last forever?

In almost all cases, it is temporary. Since the nerve is mildly irritated rather than severed, it usually fully recovers within a few weeks to a few months. Permanent damage is extremely rare.

Q. Can nerve irritation be 100% prevented?

While we can dramatically minimize the risk, it is hard to guarantee 0% in any medical procedure. The most essential prevention lies in mapping out the anatomy precisely and injecting tiny doses strictly within the designated safe zone.

Q. Is a low-swallowing formula safer for my nerves?

Formulas that produce less swelling and irritation can be highly beneficial for a comfortable recovery. However, nerve safety is much more dependent on the precise location and depth of the injection than the product itself. The injector's detail-oriented technique is the true key.