Why Dissolving Filler Sometimes Takes More Than One Session

Hyaluronic acid filler can usually be dissolved with an enzyme called hyaluronidase, but it does not always melt away in one visit. A 2026 letter in the Journal of Cosmetic Dermatology explains why: the enzyme has to physically reach the filler, and the gel's dense structure slows it down, so precise placement and sometimes repeat sessions are needed.

Why this was written

One of the reassuring features of hyaluronic acid filler is that it can be broken down if needed, whether to correct a result someone is unhappy with or to treat a complication. Many people assume that means a single quick injection will reverse everything. In practice, clinicians often find that some filler remains after the first treatment.

The authors, a group of clinicians who work with filler complications in the Netherlands, wrote this letter to explain the physical reasons behind that experience and to suggest how clinicians might improve results.

What the authors argue

This paper is a letter, not an experiment. It does not report new data. Instead, the authors apply basic principles of how molecules spread through materials, supported by earlier laboratory and clinical studies, to describe several barriers.

• The gel is dense. Modern fillers are cross-linked, which ties the hyaluronic acid into a tight network. The enzyme moves slowly into that network, and more tightly cross-linked products resist it more.
• Liquid and gel do not mix easily. The enzyme is a watery solution and the filler is a gel, so they tend to stay separate. The enzyme mostly works at the surface where the two meet.
• Filler can be tucked away. Over time, filler may sit in pockets of fat or connective tissue, or the body may form a thin capsule around it, adding distance the enzyme must cross.
• The enzyme does not last long. Once injected, hyaluronidase is broken down by the body fairly quickly, limiting how far it can travel before it stops working.

Based on this, the authors suggest that injecting the enzyme directly into the filler deposit, ideally guided by ultrasound, at several points, and with gentle massage afterward, may work better than injecting near the area. They also note that higher doses or repeat sessions may be needed for firmer, more tightly cross-linked products.

How strong is this evidence?

A letter like this offers expert reasoning, not proof. The explanations make scientific sense and fit what other studies have observed, but the authors did not test their recommendations, and they give no measured values. Some suggestions, such as massage helping the enzyme mix, are described as things that may help rather than established facts.

That said, the main message lines up with other published reviews: dissolving filler often needs more than one session, especially with firmer gels.

What it means for you

If you are having filler dissolved for a cosmetic reason, such as lumps, puffiness or a result you no longer want, it is reasonable to expect that more than one appointment may be needed. Clinicians often prefer to start with a cautious amount, wait for the effect, and then reassess. This also reduces the chance of dissolving more of your own natural hyaluronic acid than intended, which can cause a temporary hollow look. Our article on dissolving filler covers what the appointment involves.

The type of filler you have matters. Firmer products used for structure, such as in the chin or jawline, tend to resist the enzyme more than softer products. Knowing which product was used, and when, helps your clinician plan. If you are not sure, it is worth asking for your treatment records from your previous provider. Our article on filler cross-linking and firmness explains these differences.

In an emergency such as blocked blood flow, the approach is different. Clinicians use larger amounts of enzyme, repeated at intervals, because the goal is to restore circulation as quickly as possible. This is one reason physician-led clinics keep hyaluronidase on hand and follow emergency protocols.

Hyaluronidase is not right for everyone. People with a known allergy to the enzyme, or a significant allergy to bee or wasp stings, should tell their clinician beforehand. Common side effects include temporary swelling, redness and tenderness, and allergic reactions, though uncommon, can occur.

Questions to ask at your consultation

• Which filler do I have, and how firm is it?
• How many sessions might I need, and how long between them?
• Will ultrasound be used to find the filler?
• Could some of my natural volume also be affected?

Planning ahead before filler

This research is also useful before any filler is placed. Knowing that firmer products can be harder to dissolve, some people prefer to start with smaller amounts and build gradually, rather than placing a large volume at once. It is also sensible to keep a record of which products were used, where and when, especially if you have treatments at more than one clinic. That information makes any future correction more predictable.

Finally, remember that dissolving is a medical procedure with its own risks and recovery time. It is worth treating the decision to add filler with the same care.

Frequently asked questions

Does the enzyme work instantly?

Some softening is often noticed within a day or two, but swelling can hide the result. Most clinicians reassess after a week or two before deciding on more treatment.

Can filler from years ago still be dissolved?

Often yes, if it is hyaluronic acid. Older filler may be more spread out or encapsulated, which can make it slower to respond.

Does this apply to all fillers?

No. Hyaluronidase works only on hyaluronic acid filler. Other types, such as calcium hydroxylapatite or PLLA, cannot be dissolved this way.

If you are thinking about having filler dissolved, a consultation is the place to review your history, the likely number of sessions and whether dissolving is the right step for you.

Source

Murray G, Khoshnaw S, Velthuis P. Dissolving hyaluronic acid filler: the diffusion barrier to hyaluronidase efficacy. Journal of Cosmetic Dermatology, 2026. Read the study