The reason why there is so much wrong with skin care is because most "knowledge" about skin care is just assumptions. However we do not know what assumption is masquerading as fact because baseless claims about skin care are parroted by doctors, bloggers and Youtubers without anyone doing their own research to verify the claims.
One of the biggest assumptions is that hyaluronic acid fillers eventually dissolve and then it is time to get more. And while it is true that some of what is injected dissolves and is discarded by the body, it is untrue that the entirety of the filler is fully dissolved by the body.
How hyaluronic acid is broken down in the body
For hyaluronic acid to dissolve, whether the hyaluronic acid is from filler injections or from the cells in our body, there must be a source of hyaluronidase to break it down. Hyaluronidase is a class of enzymes (proteins that catalyze a reaction) that specifically break down hyaluronic acid in the body.
This means that in order for your filler to dissolve, your body must produce a regular source of hyaluronidase to the injection site over a prolonged period of time.
And this is where the problem begins: your body does NOT want to regularly produce hyaluronidase because this would cause your skin and other organs to break down.
Hyaluronic acid is a natural component of our body. It is an integral part of our cell's structure. Cells in our body from our skin to our muscles to our bones have an outer scaffolding called an extracellular matrix.
The role of hyaluronic acid in the body includes:
1. Add resilience to cartilage
2. Assist movement among muscle cells
3. Repair skin from wound damage, UV damage, mechanical damage
4. Cell interaction and communication
5. Cell adhesion
As the above roles imply, hyaluronic acid is a necessity for a functioning body. Without it, your cells would not be able to communicate, muscle function wouldn't be possible, and your skin would not be able to heal from even slight damage. Therefore it is critical for your survival that your body has a constant source of hyaluronic acid at all times. This means that your body does not want to constantly produce an enzyme that will break down what it needs for survival. And will usually just do so when an infection occurs. So your body will only produce hyaluronidase when necessary and just for short periods of time.
For example, if you have strep throat, you are infected with the streptococcus bacteria. This bacterial cell is encapsulated with hyaluronic acid which protects it from being engulfed, digested and destroyed by the body's immune cells. So in order to kill the bacteria, white blood cells in the body secrete hyaluronidase to break down the streptococcus' hyaluronic acid armor, which allows the body to kill the bacteria.
And this phenomenon in the body is how we got to the filler dissolving assumption: the body will dissolve the injected filler, but only for a set period of time, and only in particular places.
How long does the body dissolve hyaluronic acid filler for?
Although there is no scientific determination for how long the body dissolves the filler for, I will hypothesize that the majority of dissolution occurs within the first 2-4 weeks after the filler was injected. It is during this period of time that there is inflammation at the injection site, or often an allergic reaction, which means that white blood cells are healing the affected area. White blood cells secrete hyaluronidase as part of the immune response and this is what will cause filler to dissolve.
The immune response to the area is short-lived and not long-term, which means that there will not be a constant flow of hyaluronidase to the area until the hyaluronic acid is gone. If this were the case, the surrounding skin, muscle and even bone would break down along with the filler gel.
It is also important to note that the location of the filler is a factor in whether the filler can dissolve or not. If the filler is in a location further away from direct blood flow than other locations, then this means that cells that secrete hyaluronidase will not be able to reach the hyaluronic acid gel, and will therefore be unable to dissolve it.
MRI Scans show 10 year old filler
There is also evidence that patients who received hyaluronic acid fillers a decade ago, and have not had an injection since that time, still have the filler present in their body. A doctor in Australia who has performed quite a bit of filler procedures over the years noticed his patient's fillers were not dissolving at the 6-12 month mark as claimed. So he performed an MRI on these patients and found that filler that had been injected up to 10 years ago was still present in the body. This was especially true around the eye area. The video discussion of his findings can be found here.
Although there is not a lot of research on this subject, other studies have found:
1. Hyaluronic acid injections on 10 males did not show significant reduction in hyaluronic acid volume over 12 months (Becker et al., 2015)
2. Hyaluronic acid fillers can last 12 months to an 'indefinite' period of time (Tal et al., 2016)
3. Hyaluronic acid fillers were detected in the ultrasounds of patients who received fillers up to 2, 6 and 12 years ago. Interestingly, all patients denied getting filler until presented with the ultrasound evidence. Filler migration was also observed. (Master, 2021)
MRI of patient with facial fillers (Tal et al., 2016)
Cosmetic hyaluronic acid vs. natural hyaluronic acid plays a role in dissolution
One final factor to consider in the dissolving of hyaluronic acid is the difference between the hyaluronic acid produced by a natural body such as your own or a bacterium, and the hyaluronic acid made by drug companies that are injected for cosmetic and medical purposes.
Hyaluronic acid used for cosmetic and medical injections are processed to prolong their shelf life and altered to form a hydrogel to inject into the body. The modifications made to the hyaluronic acid before its injected into you changes its ability to dissolve.
All matter has something called a half-life, which is the measure of time it takes for half of that thing to reduce by half. In biology, half life is important because it tells us how long something stays in the body before being removed. For example, we want drugs to stay in our body for a certain period of time, any less and their effect will not be therapeutic, and any more and it can be come toxic. A dose of aspirin has a half life of 2-3 hours, which means that after 2-3 hours half of the aspirin has been eliminated by the body. And after 10 hours just about all of it is gone. This is a good half life because you have the drug in your body long enough to do its job, and it does not stay around so long that it will put a strain on your liver and kidneys.
Hyaluronic acid has a half-life too, but is dynamic depending on its location in the body. Hyaluronic acid has a half-life of 3 to 5 min in the blood, fewer than one day in the skin and 1 to 3 weeks in the cartilage. However, the processing and modifications made to commercial hyaluronic acid will affect this half life and prevent the body from dissolving it efficiently, which is another reason why fillers can be detected in the body over 10 years post injection.
Assumption over reality
The above findings highlight the importance of not assuming fact in skin care. In a previous post I took the "assumed" fact that hyaluronic acid holds 1000x its weight in water and debunked this claim in the lab. And found it barely holds 10x its weight in water.
The assumption that hyaluronic acid fillers dissolve within a year is the reason why we are seeing people with severely plumped, distorted faces. They believe that their filler is gone, and they need to get more. However, the filler may not have actually left, it may have just migrated, leading to sagging skin, a distorted look and possible medical complications.
I believe that less is more in beauty, that we should focus less on cosmetic procedure and more about enhancing what we have naturally through skin care, proper diet and a healthy view of ourselves. I also believe that the long-term effects of this increasingly popular procedure will start to reveal itself soon as more people go overboard with filler and this will lead to more procedures to achieve a non-filler look.
Perhaps it is just best to avoid these sort of procedures in the first place and stick to skin care.
References
Becker, M., Balagué, N., Montet, X., Calmy, A., Salomon, D., & Toutous-Trellu, L. (2015). Hyaluronic acid filler in HIV-associated facial lipoatrophy: evaluation of tissue distribution and morphology with MRI. Dermatology, 230(4), 367-374.
Di Girolamo, M., Mattei, M., Signore, A., & Grippaudo, F. R. (2015). MRI in the evaluation of facial dermal fillers in normal and complicated cases. European radiology, 25(5), 1431-1442.
Leng, Y., Abdullah, A., Wendt, M. K., & Calve, S. (2019). Hyaluronic acid, CD44 and RHAMM regulate myoblast behavior during embryogenesis. Matrix Biology, 78, 236-254.
Lin, X., Patil, S., Gao, Y. G., & Qian, A. (2020). The bone extracellular matrix in bone formation and regeneration. Frontiers in pharmacology, 11, 757.
Master, M. (2021). Hyaluronic acid filler longevity and localization: magnetic resonance imaging evidence. Plastic and Reconstructive Surgery, 147(1), 50e-53e.
Papakonstantinou, E., Roth, M., & Karakiulakis, G. (2012). Hyaluronic acid: A key molecule in skin aging. Dermato-endocrinology, 4(3), 253-258.
Rivera Starr, C., & Engleberg, N. C. (2006). Role of hyaluronidase in subcutaneous spread and growth of group A streptococcus. Infection and immunity, 74(1), 40-48.
Tal, S., Maresky, H. S., Bryan, T., Ziv, E., Klein, D., Persitz, A., & Heller, L. (2016). MRI in detecting facial cosmetic injectable fillers. Head & face medicine, 12(1), 1-7.