Hyaluronic Acid is one of the most commonly used and marketed ingredients in topical skin care products to date, with no signs of slowing down. Hyaluronic acid is a compound that naturally occurs in the body and provides support, protection, and insulation in connective tissue, especially the skin. Hyaluronic acid promotes a plump and hydrated appearance to well-cared-for skin, explaining its popularity across the skin health industry. So what is hyaluronic acid, when and how often should you use it, and are there any downsides? We’ll discuss these questions in detail throughout this blog.

Hyaluronic acid is known as a humectant, a class of ingredients that retain moisture by binding with many times its weight in water. This means that when applied to skin, hyaluronic acid can bind and lock in water molecules, acting as a time-extended water supply to skin cells, thus preventing moisture from leaving the skin’s surface¹.

Hyaluronic acid comes in a variety of sizes, each with different mechanisms and penetration capabilities. Generally, they can be categorized based on their molecular weight:

• Low molecular weight: Below 350 kDA, hyaluronic acid with a low molecular weight permeates deep into the skin to stimulate collagen synthesis and stem cell maintenance.⁹
• Medium molecular weight: At an average of 680 kDA, medium molecular weights strengthen and fill out the skin by maintaining elastin production⁹
• High molecular weight: A size greater than 1800 kDa is considered to have a high molecular weight which is made up of cross-linked hyaluronic acid used to form a film on the skin that retains moisture over time.⁹

Hyaluronic acid will attract and bind to any available water molecules, whether those water molecules come from within the skin or from the environment, therefore it is recommended that hyaluronic acid is applied to damp skin to avoid pulling water from within the skin.Hyaluronic acid can always aid in keeping skin hydrated, but there are a few optimal application times that will help its effectiveness. When hyaluronic acid is present within a moisturizer, you should apply it just after cleansing the skin while it is still damp. This will help ensure that the hyaluronic acid has readily available water to bind to and will help bolster the skin’s ability to retain moisture². Moisturizing twice a day with a peptide moisturizer after cleansing with a gentle gel cleanser has the potential to help maximize the effectiveness of hyaluronic acid.

If you are wondering, “can I use niacinamide with hyaluronic acid,” the answer is yes. Both are water-based humectants that can complement each other when combined.

Hyaluronic acid is also commonly delivered through serums. If using a serum, recommended application is once or twice a day after cleansing, immediately followed by applying a moisturizer to the treated area³. Since serums tend to penetrate deeper into your skin, it's important to moisturize the outer layer of skin to lock in the moisture.While you may be skeptical of using an “acid” on a daily basis, hyaluronic acid is completely safe to use daily and even twice daily. Though it is technically considered an acid, due to its low pH, hyaluronic acid is not a chemical exfoliant like other commonly used acids. This and the fact that it is naturally produced in the body means that you can use it every day without the risk of damaging your skin (3).

There is potential to overuse hyaluronic acid, which ironically causes skin dehydration, and could lead to irritation and inflammation. Due to hyaluronic acid’s water-binding capacity, when a disproportionate ratio of hyaluronic acid to water is introduced to skin, the hyaluronic acid can draw water from deep within your skin, thereby dehydrating the lower layers of skin⁴. To determine the correct dosage to apply to your skin, you should begin by applying small amounts and working up to larger amounts as your skin becomes accustomed to the application of hyaluronic acid. You should also be sure to apply hyaluronic acid to damp skin, or you can mist skin with water after applying hyaluronic acid to ensure it has enough external moisture to bind to.Though it may seem obvious, water is a fundamental molecule for optimal cellular function and renewal. Without adequate sources of water, cells, and specifically the energy sources of cells, called mitochondria, cannot function properly. While hyaluronic acid does not explicitly lighten hyperpigmentation in skin, small molecule sizes of hyaluronic acid can penetrate deep into the skin and hydrate the systems responsible for collagen synthesis. From this increased hydration, the cells responsible for producing new collagen can do so more efficiently, in turn increasing collagen production in skin⁵. With increased collagen levels, new skin cells can be produced more rapidly, which over time should result in decreasing the appearance of dark spots on treated areas.Much like mitigating the appearance of hyperpigmentation, brightening skin often relies on the synthesis of new skin cells. Because hyaluronic acid serves as a water supply for skin cells, hyaluronic acid may aid in optimal cell renewal, providing a healthy groundwork for your cells to begin the process of repair on their own.Retinol and hyaluronic acid are arguably two of the most well-known and popular skin care ingredients, but their mechanisms and effects are very different. While retinol is primarily touted for its anti-aging effects, hyaluronic acid is more broadly praised for its hydrating effects on skin. In general, hyaluronic acid is gentler and can be used on a more frequent basis, while retinol tends to be harsher on skin and should be used sparingly, especially for sensitive skin types.

Retinol is a derivative form of vitamin A which, when applied to skin, can increase skin’s cellular turnover rate and collagen production. Due to these effects, retinol is famed for its ability to combat the visible signs of skin aging, such as wrinkles and fine lines, while also improving skin tone ⁶. Unfortunately, there are some retinol dangers to be aware of. This ingredient commonly causes redness, irritation, and skin peeling, especially in those with sensitive skin, which can damage skin if not offset by a highly effective moisturizer. For this reason, many people may need to limit their use of retinol and understand when to stop using retinol when symptoms persist.

As previously discussed, the main hyaluronic acid benefits come from its hydrating properties that help keep your skin moisturized and healthy. For this reason, it could be argued that hyaluronic acid is better than retinol, as it is far less likely to cause negative side effects. However, this is much like comparing apples to oranges, as they serve two different purposes.

Rather than choosing between using hyaluronic acid and retinol, the two ingredients can be used synergistically⁷. By using the two in conjunction with one another, the drying and irritating effects of retinol can be offset by the hydrating properties of hyaluronic acid.Fortunately because of its inert and soothing properties, hyaluronic acid is suitable for any skin type and can be integrated into almost any skin care routine. While most skin types would benefit from the application of hyaluronic acid, those with dry skin will experience the most benefit from its use.

Hyaluronic acid is also a great compliment to any moisture-providing product, since it binds to and holds water molecules. Additionally, since hyaluronic acid is non-irritating at normal concentrations and non-comedogenic, it likely won’t cause problems for skin already prone to acne breakouts – making it an essential part of many moisturizers aimed at helping those with oily skin⁸.Most people could stand to benefit from hyaluronic acid. In particular, those with dry skin could benefit from the hydrating properties of hyaluronic acid, especially during the winter. In addition to those with dry skin, people who want to increase skin elasticity and in turn reduce the appearance of fine lines and wrinkles may also consider using products that contain hyaluronic acid. Finally, since hyaluronic acid can promote collagen synthesis, those with aging skin may also consider using hyaluronic acid to offset the natural decline in collagen levels that occur with age.OS-01 FACE, a Topical Supplement designed to promote skin health on the molecular level, contains three sizes of hyaluronic acid, aimed at permeating each layer of the skin. By penetrating deep into the skin, it can retain moisture in each layer as well as stimulate and maintain collagen and elastin production, in turn boosting epidermal regeneration, and stem cell maintenance.

• High molecular weight: Made from cross-linked hyaluronic acid with high water-binding capability, this size of hyaluronic acid forms a barrier on the skin that locks in moisture.
• Medium molecular weight: Of similar size to the naturally occurring hyaluronic acid in skin, this size strengthens and fills out the skin by maintaining elastin production.
• Low molecular weight: The smallest size permeates deep into the skin to stimulate collagen synthesis and stem cell maintenance.

In addition, OneSkin’s proprietary peptide, OS-01, has been scientifically proven to increase the activity of a key gene associated with hyaluronic acid production*, allowing skin to produce more hyaluronic acid on its own.

*Shown in lab-grown ex vivo human skin models

• Hyaluronic acid is naturally found in the body and responsible for much of the underlying structure of the skin.
• Hyaluronic acid is a humectant, a compound with great water retention properties.
• Hyaluronic acid can be used twice a day, ideally while the skin is still damp after cleansing.
• Hyaluronic acid can be used daily as it is non-irritating and non-comedogenic.
• Hyaluronic acid may reduce the appearance of hyper-pigmentation by boosting collagen synthesis.
• Hyaluronic acid can promote skin elasticity and repair by boosting elastin and collagen production.
• Hyaluronic acid can be used with retinol to offset retinol’s potential irritating side effects.
• Hyaluronic acid is best suited to those with dry skin, however, any skin type will benefit from its use.

By Philip Tajanko: Philip is studying Bioengineering at the University of California - San Diego and is passionate about scientific writing and hormonal research.

Sources:

1. https://www.sciencedirect.com/topics/medicine-and-dentistry/humectant
2. https://www.lorealparisusa.com/beauty-magazine/skin-care/skin-care-essentials/best-times-to-apply-moisturizer
3. https://www.healthline.com/health/beauty-skin-care/how-to-use-hyaluronic-acid#in-your-routine
4. http://barefacedtruth.com/2015/03/31/hyaluronic-acid-yes-size-does-matter/
5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4822517/
6. https://www.lorealparisusa.com/beauty-magazine/skin-care/anti-aging/4-ways-retinol-can-help-improve-the-look-of-your-skin
7. https://pubmed.ncbi.nlm.nih.gov/14976384/
8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4025519/
9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7464276/