Does hyaluronic acid filler really disappear in 6 months?

“Filler dissolves, so it’s fine.” I hear this often. Hyaluronic acid is a substance the body already contains, so the filler breaks down over time, and it’s usually said to last about 6 months to 1 year. As far as the visible effect goes, that’s broadly true. But when you look with imaging, the story is a little different.

In a 2024 study, 2 radiologists reviewed MRI scans of 33 people who had hyaluronic acid filler in the midface. Filler was visible in all 33, and not one person’s filler had completely disappeared within 2 years of injection. For 21 people, it had been 2–5 years since their last injection, and for 12, more than 5 years; at the longest, filler injected 15 years earlier was still present. In 11 people, a large amount was judged to remain.

A report also described 3 people whose filler, injected around the eyes, remained for up to 9 years before gradually moving toward the skin surface and causing a swollen look. All 3 improved with a dissolving drug.

Why does it last so long? In 2018, Japanese researchers injected filler under the skin of rats and followed it with MRI for 64 weeks. After 64 weeks, 74.8% of the original volume remained, and fibrous tissue, blood vessels and fat cells had grown into the filler mass. This means that part of the filler is replaced by your own tissue, which keeps the volume in place. However, this was a study in rats, so it can’t be applied directly to people.

These studies have limitations too. The human study included only people who had MRI scans, and some of them had the scan because they were worried about swelling. When and how much filler they had received also relied on their own memory. Even so, it’s clear that the findings differ from the idea that “it’s all gone in 6 months.”

In practice, this means two things. First, if you add more to the same spot each time you feel the effect has faded, it can keep building up on top of filler that remains out of sight. This is one way a face can come to look gradually heavier over several years. Second, that’s why it matters to use only as much as is needed from the start. It’s also why 3cc Face LINE ON works within a set amount and chooses only the areas where support has weakened.

If you’ve had filler before, please tell me at your consultation when, where and how much, as best you can remember. Taking remaining filler into account is how I can accurately decide where to place new filler and how much to use.