Firmness and Fibrosis After Filler: A Lesser-Known Reaction

A 2024 report described 23 women who developed a firm, rubbery bulge beside their smile lines after hyaluronic acid filler in the nasolabial folds. The authors believe the lump was scar-like fibrous tissue rather than filler, because dissolving enzyme did not help while small steroid injections did. It is a small, early-stage study, but it highlights a lesser-known reason a treated area can feel firm or look different when smiling.

Why this was studied

When a lump or firmness appears after hyaluronic acid filler, the usual assumption is that it is leftover product, which can often be dissolved with hyaluronidase. The authors noticed a group of patients in whom this did not work. They wanted to describe the pattern so other clinicians could recognize it and avoid repeated, unhelpful treatments.

What the researchers did

This was a retrospective case series from a dermatology practice. The authors described 23 women, aged 38 to 65, all of whom had received hyaluronic acid filler elsewhere to soften the folds running from the nose to the corners of the mouth. Diagnosis was based on examination and photographs. No imaging or tissue samples were reported.

What they found

The women were generally happy that their folds looked softer at rest. Their concern was that the face felt heavier and looked unnatural when they smiled. On smiling, the lower part of the fold pushed the cheek upward into a rounded bulge, and the outer corner of the upper lip could appear thinner or slightly lifted.

On examination, the authors felt a firm, sausage-shaped band under the skin just outside the lower two-thirds of the fold. It felt rubbery rather than soft like filler, and it was found only in this area, not at other sites where the same women had filler.

Treatment results were striking within this small group:

• Hyaluronidase was tried in several patients and did not help.
• Small injections of the steroid triamcinolone directly into the bulge led to near-complete flattening within about four to ten weeks in the cases shown.
• Some patients needed a second injection, and one needed three.
• No patient returned with the problem coming back, though long-term follow-up was not reported.

Why might this happen?

The authors propose that hyaluronic acid can stimulate the skin's collagen-making cells, and that the repeated stretching of the lower smile line during talking, chewing and laughing may push this response too far, creating a band of firm, fibrous tissue. That would explain why the problem appeared only in this highly mobile area and why an anti-scarring steroid helped when the dissolving enzyme did not.

This explanation is a hypothesis. Without tissue samples or imaging, the study cannot prove the lump was fibrous tissue. Our article on filler cross-linking and firmness explains how products differ in how firm they feel.

How this differs from other lumps

Filler-related lumps come in several types. Product that sits too superficially or in too large an amount often appears soon after treatment and usually softens with hyaluronidase. Inflammatory or infection-related lumps tend to be red, warm or tender. Granulomas are an immune reaction that typically appears months or years later. The reaction described here seems to be different again: a firm, non-tender band that changes how the face moves, with no sign of inflammation. Recognizing these differences helps a physician choose the right treatment instead of repeating one that is unlikely to work.

How strong is this evidence?

This is a small, retrospective case series without a comparison group, which places it low on the evidence ladder. In particular:

• It cannot say how often this reaction occurs.
• The cause is inferred from the response to treatment, not confirmed under the microscope.
• Products, amounts and injection techniques from the original treatments are not described.
• Follow-up was short and informal.

The authors suggest injecting the less mobile upper part of the fold where possible, but that recommendation also needs testing in larger studies.

What it means for you

If a filler-treated area feels unusually firm or your smile looks different weeks or months after treatment, it is worth having it assessed rather than assuming it will settle. Not every firm area is leftover product, so dissolving it is not always the right first step.

A careful assessment will usually look at when the change appeared, how it behaves at rest and when smiling, whether it is tender or red, and what product was used. Steroid injections carry their own risks, such as thinning of the skin or a dent if too much is used, so treatment should be gradual and physician-directed. Our article on delayed swelling and lumps after filler covers other causes of late changes.

Contact your clinic for any treated area that becomes red, warm, painful or swollen, which may signal inflammation or infection. Seek urgent care for skin colour changes or severe pain soon after an injection, or any change in vision.

Questions to ask at your consultation

• How might filler in this area look when I smile, not just at rest?
• What would you do if the area became firm and did not soften?
• Is filler a good way to address my concern, or would another option suit me better?

Frequently asked questions

Is some firmness after filler normal?

Yes. Many areas feel a little firm for a week or two as swelling settles and the product integrates. A firm band that lasts for months, or changes your smile, should be checked.

Why would dissolving filler not work?

Hyaluronidase breaks down hyaluronic acid. If the firmness is mainly the body's own fibrous tissue, as these authors suggest, the enzyme has little to act on.

Are steroid injections safe for this?

Low doses injected precisely were helpful in this series. Side effects can include temporary skin thinning or a small dent, which is why doses are kept small and treatment is spaced out.

If you have concerns about a firm area after filler, or want to understand how filler might affect your smile, HealthPark Medical Aesthetics can review your history and options in a consultation.

Source

Peros I, Haneke E. Fibrotic reaction to hyaluronic acid fillers in the face. Journal of Cosmetic Dermatology, 2024. Read the study