If the notion of applying acids to your skin sends you running screaming to the hills, take heart. Even if the word acid conjures up horror movies images of bubbling test tubes, products with acid can be an effective pathway for rejuvenating skin health and glowing complexion.

Acids are a common ingredient in beauty products since they help with many different issues: They fight acne, reduce age spots, scarring, and appearance of wrinkles, and even out skin tone.

PH value

So let’s take the time machine back to our chemistry class. You probably remember that PH is used to measure how acidic or alkaline (or basic) a substance is. PH 7 denotes perfectly neutral, and anything below is acidic while above is alkaline.

When you hear acid, you’re probably thinking about something green and nasty, right? Photo by Bill Oxford

For example, water is measured as having a pH of 7 and soap has a PH value of 9-10. To maintain a healthy skin barrier, your skin should measure at PH 5.5.

At the most basic level, an acid is a molecule or ion that can either donate a hydrogen or accept an electron pair. So, an acid for one has a PH lower than 7 and it can lower the PH levels of your skin.

The most commonly used acids are exfoliation hydroxy acids, AHAs and BHAs. The other type of acid is humectant such as hyaluronic acid. But we’re jumping ahead. Let’s take them one by one.

Ascorbic Acid

You probably know it as vitamin C. It’s water-soluble and a powerful antioxidant. Most likely, you didn’t classify it as an acid, but technically it is because its PH value is below 7.

Vitamin C is regularly recommended by dermatologists because it’s an antioxidant that helps to protect skin from free radicals. And as it helps boost collagen formation, it has anti-ageing properties. Lastly, by disrupting the production of melanin, the skin’s pigment, it helps even out skin tone.

Azelaic Acid

This is an ingredient that naturally occurs in grains and is also produced by the yeast on your skin. It’s often used in products for acne but it’s also for treating discolouration such as melanoma.

Citric Acid

As you probably guessed from its name, this acid is derived from citrus fruits. It’s exfoliation and has antioxidant properties.

Ellagic Acid

Like azelaic, it’s a plant compound. It naturally occurs in fruits such as berries and pomegranate or nuts. Its effects are similar to azelaic and is used to even out skin tone.

Ferulic Acid

When you buy a vitamin C or E serum, you’ll often find ferulic in the ingredient list. It’s used both as an anxilliary ingredient to stabilise the vitamin C and as it’s a potent antioxidant itself, it also protects the collagen and elastin structures in your skin.

Glycolic Acid

Is a well researched AHA and can be found in anything from face washes to serums and creams. As an exfoliator, it helps brighten and freshen up your skin and so improving the texture.

Hyaluronic Acid

Wait, what? Normally, acids are associated as being exfoliators. But since its PH is lower than 7, it’s classified as an acid. It’s a humectant famous for its water-retaining properties. So, it’s often used in products that strengthen the skin barrier and so plump up the outer layer of the skin.

Kojic Acid

Bacteria used in the production of rice wine (sake) make this substance. It also can be found in mushrooms native to Japan. Kojic acid suppresses tyrosine, which is an enzyme needed in the production of the pigment melanin. This helps fight discolouration and so it added to many Asian skin care products.

Lactic Acid

Lactic acid is the best researched AHA after glycolic acid. You probably know of the legend in which Cleopatra is said to bathe in goat’s milk. That’s because the people realised that the lactic acid found in milk had a softening, moisturising (and of course exfoliating) effect on their skin. This AHA is gentle enough for people with sensitive skin.

Linoleic (And Oleic) Acid

Both are not what you’d normally think of when hearing skin acids. They’re fatty acids found in various plants, including nuts, camellia flower, and rosehip oil. They’re nourishing and moisturising. They also have antioxidant and anti-inflammatory properties.

Malic Acid

Although commonly used, malic is less well known. It’s an AHA and so smoothes out skin texture. It’s also used in anti-ageing beauty products for it boosts the production of collagen.

Mandelic Acid

Even though it has a high acidity it’s less irritating than glycolic acid. It’s an AHA derived from bitter almonds.

Retinoid Acid

If you’re using a vitamin A product, you’ll find that the active agent is retinoic acid. This is what’s inducing necrosis of cells, aka cell turnover. Vitamin A is the queen of acids. It’s a well-researched ingredient, known to be an effective anti-ageing agent. Aside from accelerating skin cell turnover, it boosts collagen production, cleans pores, and evens out skin tone.

Salicylic Acid

If you’ve ever bought an over-the-counter product for treating acne, the product contained salicylic acid. It’s the only BHA and it exfoliates the outer layer of your skin. It breaks down the things that clog your pores, like dead skin cells, dirt, and excess oil.

Tartaric Acid

Similar to mandelic, tartaric acid is not as widely known. It’s found naturally in many plants and fruits, including grapes. It’s classified as an AHA and is an exfoliant. It’s also used to regulate the PH so that other AHAs it’s formulated with function optimally.

Ursolic Acid

Another relatively unknown acid, ursolic acid is found in the peels of apples and fruit seeds. It’s used in skin and hair care for many reasons. For one, it encourages blood flow to the top level of the skin, which for example improves scalp conditions and the flow of nutrients to the root of the hair. In skin care, it has been used in products to help photo-damaged skin because it slows the appearance of wrinkles and age spots.


As you’ve seen, acids are a common ingredient, because they help improve your skin in many ways. They can be nourishing, brightening, retaining water, or smooth out fine lines.

If you enjoyed this comprehensive guide to acids in skincare, I’d be delighted if you could share it on social media.

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