The ESK blog
Using Acid On Your Skin
07 February 2024
Dr Anne Thomson
If you’re new to skincare you might find the idea of putting acid on your face more than a little….crazy. Even if you’re a seasoned skintellectual, you may still be a tad confused by all the acids coming onto the market.
The good news is some of the best ingredients in skin care these days fall into the acid category. And the even better news? There is an acid for everyone! Whatever your skin type (yes, even sensitive skin) and whether you are dealing with acne or aging or anything in between, there is likely to be an acid-containing product for you.
Skin pH
The first thing to say when talking about skin acids is that the skin’s natural pH is acidic (around 4.9): your skin actually wants to be acidic. Turns out many common skin conditions are associated with an increased skin pH (more alkaline) including acne, rosacea and eczema. There is increasing evidence that we can help these conditions just by restoring the acidity of the skin. Meaning acids in skincare are already ahead of the game!
Ok, chemistry lesson done, onto the acids…
Hyaluronic Acid (HA)
First up is one of our favourites, hyaluronic acid. Not strictly an acid, it’s a complex sugar that occurs naturally throughout our bodies in places like our joints, eyes and of course our skin. It’s best known in skincare for its moisturising properties suitable for all skin types, but it actually does a lot more than that.
In the skin, it is vital for supporting the extracellular matrix – or scaffolding - of the skin, literally holding it up. It does this in a number of ways including by promoting collagen and elastin production, skin cell regeneration, wound healing and maintaining the skin’s hydration. As for its moisturising power, HA can attract and bind water molecules up to 1000 times its own weight. Nice!
As we age, our body starts to lose HA, with noticeable effects after the age of 30. We see increasing dryness, sensitivity, and of course a loss of elasticity and the unwelcome appearance of fine lines and wrinkles.
The good news is, we now have emerging evidence that using HA in skincare can yield significant improvements in the skin’s overall appearance, with fewer fine lines and wrinkles, smoother skin and a big boost in hydration. It can even help with rosacea and seborrheic dermatitis.
All skin types can usually tolerate and benefit from HA. Different HA molecule sizes (known as molecular weights) have different effects on and in the skin; large size HA is usually well tolerated by all skin types, even the most sensitive. Smaller size HA is generally well-tolerated too but can occasionally cause irritation due to its deeper penetration (the upside of which is it’s more effective).
HA is the main ingredient in many in-clinic dermal filler injections but for at-home use, you’ll find it in serums, creams and microneedle patches. You can use it daily, or even twice daily; look for a formulation which contains a mix of molecular weights for best results.
Alpha-hydroxy Acids (AHA)
AHAs are naturally occurring fruit acids that are best known in skincare as chemical exfoliators; they loosen the bonds that hold the superficial layer of skin cells together, allowing these dull, rough cells to slough off to reveal the fresh new skin cells below.
The two best studied AHAs are glycolic acid and lactic acid. Both have been shown to smooth the skin, reduce wrinkles, improve skin elasticity, skin tone and hydration. They can also flush out and block production of excess pigment and even combat acne.
But wait, that’s not all! Using AHAs regularly has also been shown to improve the levels of hyaluronic acid in the skin (see above) as well as enhance the effects of retinal. Win-win!
You’ll find AHAs in cleansers, serums, creams or in-clinic peels. Use them at night and make sure to use a mineral sunscreen (like zinc oxide) during the day.
Glycolic acid is not suitable for sensitive skin or rosacea, but fear not, because we now have…
Poly-hydroxy Acids (PHA)
PHAs are similar to AHAs in that they exfoliate and smooth the skin surface, but they are much more gentle than their AHA cousins. The two best studied ones are lactobionic acid and gluconolactone.
Like AHAs, they are chemical exfoliators, speeding up the process of shedding old skin cells to reveal the fresh new ones underneath.
Also like AHAs, they do more than just exfoliate. Studies show they have antioxidant and moisturising properties, improve the skin barrier function, help reduce pigmentation, and help build collagen. Plus they combat acne.
But where they differ from AHAs is that they are super gentle and can be used in the most sensitive of skin types, including rosacea.
Salicylic Acid
Often incorrectly labelled as a beta-hydroxy acid (BHA), salicylic acid gently exfoliates the skin and is a proven ingredient for managing acne and reducing the signs of sun-induced ageing. Being related to aspirin, salicylic acid has anti-inflammatory and anti-microbial properties and is usually super well tolerated even by sensitive skin.
Its exfoliating effects can be enhanced when formulated with urea, a (humectant) moisturiser and it is extremely effective as a spot treatment for pimples when delivered via a microneedle patch. A very handy little acid this one!