Hyaluronic acid is a powerful humectant that helps to prevent water loss and strengthen your skin's natural moisture barrier, resulting in hydrated, soothed skin. Even though it's called an 'acid', hyaluronic acid is the complete opposite of retinol serums, as well as glycolic, lactic and salicylic acids. It won't provide an exfoliating effect, or rid you of dead skin cells, dark spots and blemishes.

Although hyaluronic acid is a natural component of skin, the ingredient you find in hyaluronic acid serums and creams is a synthetic version. And, before you worry about putting this acid on your skin, remember not all acids are astringent. Milk is slightly acidic, as is our natural skin mantle. Hyaluronic acid falls at between 5.0 (the same acidity as a cup of milky coffee) and 8.0 (which is almost neutral) on the pH scale, while our skin usually sits between 4.5 and 6.2, making it a very gentle match.

There are countless benefits of hyaluronic acid. According to Dr LoGerfo, the beauty of hyaluronic acid really lies in its astounding humectant properties, which enable the ingredient to attract and hold up to 1,000 times its weight in water.

Not only does this keep the skin supple and hydrated, but it also helps to uphold elasticity, soothe irritated skin, and decrease the appearance of fine lines and wrinkles. As a result, Dr Lolis says, hyaluronic acid can be a great addition to any skincare routine, regardless of your particular concerns.

There are a few different factors to consider, so we'll break it down below:

• Concentration: A concentration of 0.5-1% is ideal for all skin types, with the maximum recommended being 2%. Hyaluronic acid can't be massively potent, as it becomes too thick and gloopy and unpleasant to use.
• Formulation: Some formulas have added ingredients such as ceramides, AHAs, and vitamin B5 included to deliver increased benefits, such as plumping, brightening, and soothing. You can also find formulas combined with humectants like glycerin, beta-glucan and sodium PCA, which increases the hydrating power.
• Skin type: You want your hyaluronic acid to work in tandem with your skin, so check the ingredient list to see what other ingredients have been included. Those with sensitive skin would benefit from soothing ingredients like aloe vera and vitamin E, those with acne-prone or oily skin may prefer a lightweight, oil-free serum with salicylic acid or niacinamide, and those with mature skin may want a formula rich in plumping ceramides.

Wondering how to use hyaluronic acid serum in your skincare routine? The best way to is on slightly damp skin after cleansing or a shower, as the molecule needs moisture to work in the first place.

If you apply hyaluronic acid to dry skin in a dry climate such as your heated flat in winter, you're in danger of making your skin even more parched. Dr Sophie Shotter, aesthetic doctor and founder of Illuminate Skin clinics, explains: “Hyaluronic acid will draw moisture from wherever it can find it, including the deeper layers of your skin, if there is no humidity in the air.”

So, after popping your serum on damp skin, make sure to follow up with a moisturiser packed with emollients, such as glycerin and ceramides, to lock in the hydration.

Wondering if you can pair hyaluronic acid with other face serums, like retinol? The answer is a resounding yes.

“Hyaluronic acid is extremely gentle and versatile, so it is okay to use with other products,” Dr. LoGerfo explains. “Sometimes it’s helpful to use hyaluronic acid with other ingredients that can be slightly irritating — like retinol, alpha-hydroxy acids, and salicylic acid — because it can help tone down the irritant nature of those products.”

The expert advises using retinol serums and hyaluronic acid together at night, although you can use a hyaluronic acid serum alone in both the morning and at night.

If you're a die-hard fan of the best vitamin C serums, you'll be pleased to know that hyaluronic acid and vitamin C are a dream team for your complexion.

As we know, hyaluronic acid helps to keep the skin hydrated, and it's a perfect pairing when added with vitamin C, which lessens the look of dark spots, fine lines and sun damage. The result is a hydrated, bright and smooth appearance.

Vitamin C even improves hyaluronic acid's effectiveness by supporting its ability to retain moisture, prevent water loss and strengthen the skin barrier.

And, as above with retinol, the ingredients are often paired together as too much vitamin C can be drying and irritating. Hyaluronic acid brings a nourishing, soothing element to help keep your moisture barrier in check.

As for which to use first, apply the formula that has the thinner, lighter consistency first, and then apply the thicker serum, moisturiser and SPF on top.

Different weights of hyaluronic acid refer to its molecular mass, or the size of the molecule. You can get hyaluronic acid in molecular weights of low, medium or high.

The size of a molecule determines how deeply it can be absorbed into the skin. The largest, heaviest molecules will sit on top of the skin and attract water to the outermost layer, while smaller molecules can be absorbed through the skin barrier, where they attract water internally to plump skin underneath.

But whichever size your serum has, they all have benefits…

• High Molecular Weight Hyaluronic Acid has larger molecules that sit on the skin's surface, forming a protective barrier and preventing moisture loss, delivering immediate hydration.
• Medium Molecular Weight Hyaluronic Acid uses not too small, not too big molecules to help retain moisture slightly below the skin’s barrier.
• Low Molecular Weight Hyaluronic Acid has small molecules that absorb deeper into the skin's layers, providing long-lasting hydration.