How long does hyaluronic acid filler last, and what does it depend on?

A gel designed to last, but not forever

Hyaluronic acid is already present in your skin, but it is renewed very quickly there: its half-life is one to two days. Natural enzymes, hyaluronidases, constantly break it down. For an injected gel to last for months, its chains are linked together: this is called crosslinking. This mesh slows the enzymes' access and delays degradation.

The gel remains biodegradable. It is gradually removed by these enzymes and by oxidising molecules, free radicals. The effect is therefore temporary, and this is also what allows it to be dissolved if needed, as I explain in the article on reversibility.

How long hyaluronic acid filler lasts depends on the area

In studies, the visible effect lasts from a few months to a year and a half, depending on the product, the technique and the person. The treated area matters a great deal:

• Lips: in a randomised trial, the effect was still visible in most people six months after the injection.
• Cheeks: one year after the injection, 85% of people still had an improvement.
• Nasolabial folds: the improvement was maintained for up to 18 months, with one touch-up in between.

These figures describe groups, not a promise for each person: even on the cheeks, some people no longer had an improvement after one year. That cheek trial was, moreover, conducted with the participation of the manufacturer of the gel tested.

What makes the duration vary

• How mobile the area is. The lips move constantly to speak, eat or smile. This mechanical stress is one of the factors that shorten the duration.
• The rheology of the gel, that is, how it behaves under stress. A firm gel resists deformation and supports the tissues; a soft gel spreads and follows movement.
• Crosslinking. In principle, the more crosslinked the gel, the better it resists enzymes.
• Technique: the quantity injected and the depth.
• Your body. Metabolism, diet and lifestyle play a part, though this cannot be predicted precisely for each person.

These factors combine in complex ways. A review published in 2026 by experts linked to a filler manufacturer points out that laboratory measurements predict the actual duration rather poorly. So I choose the gel according to the area, from one of the two ranges used at the practice (Restylane or Hyafilia), then I judge on your photographs rather than on a data sheet.

The gel goes, the effect stays for a while

Resorption is gradual: the effect fades little by little, with no sudden drop.

It is also important to distinguish the visible effect from the presence of gel. An MRI study found hyaluronic acid in all 33 people examined, at least two years after the injection, and up to fifteen years in one of them.

These images call for caution: MRI sees a mixture of gel, water and newly made collagen. The gel also appears to stimulate tissue remodelling, which can extend the visible benefit beyond the gel itself.

Why maintenance often needs less product

This follows from the above: when you come back, we do not start from zero. Part of the support is still there.

One study of 52 people measured this on nasolabial folds: at touch-ups, the average quantity injected was less than half the initial quantity. In those followed to the end, with two touch-ups, the improvement was still maintained three years after the first session.

So I do not schedule a "top-up" on a fixed date. We compare your photographs with those taken before the first treatment, with the same measurements. If the support is still there, we add nothing. Adding out of habit can lead to overfilled faces, which I discuss in the article on perceptual drift.

In practice

The session takes 30 to 45 minutes, with an anaesthetic contained in the product, and the effect is immediate. We meet again around day 15: same photographs, same measurements, and a touch-up if needed. The first time, we always do less.

After that, the examination sets the pace, not the calendar.