Comprehensive guide to skin acids

Skin Acids

Skin acids are among the most versatile and effective ingredients in modern skincare. While the word "acid" may sound intimidating, many skin acids are designed to improve the health and appearance of your skin. Some gently exfoliate away dead skin cells, while others hydrate, brighten, calm inflammation, strengthen the skin barrier, provide antioxidant protection, or help reduce acne and pigmentation. Each acid has a unique purpose, making it important to choose the right one for your skin type and concerns.

The guide below explains some of the most common skin acids you'll find in skincare products, what they do, and who they're best suited for. Understanding how each one works can help you build a routine that addresses your skin's unique needs.

AHAs (Alpha Hydroxy Acids):

are a group of water-soluble chemical exfoliants that can be naturally derived from fruits, milk, or sugar cane, although many skincare formulations use synthesized versions for stability and consistency. The most common AHAs are Glycolic Acid and Lactic Acid. AHAs work by dissolving the bonds that hold dead skin cells together, allowing them to shed more easily. Regular use helps reveal smoother, brighter skin, improves texture, and encourages healthy cell turnover.

BHAs (Beta Hydroxy Acids):

are oil-soluble chemical exfoliants that are especially beneficial for oily, acne-prone skin. Unlike AHAs, BHAs penetrate into the pores where oil and dead skin cells collect. They help dissolve excess sebum, loosen clogged pores, and reduce blackheads and breakouts while also calming inflammation. The most widely used BHA in skincare is Salicylic Acid.

Glycolic Acid:

is an AHA derived from sugar cane and has the smallest molecular size of all the AHAs, allowing it to penetrate the skin more deeply. It exfoliates the outermost layer of dead skin cells (the stratum corneum), leaving skin smoother, brighter, and more even in tone. Glycolic Acid also helps improve the appearance of fine lines, sun damage, hyperpigmentation, rough texture, and mild acne. When used at the appropriate strength, it offers a gentler, more even exfoliation than many physical scrubs.

Salicylic Acid:

is the most common BHA used in skincare. Because it is oil-soluble, it can penetrate deep into pores to dissolve excess oil, loosen clogged follicles, and remove dead skin cells that contribute to acne and blackheads. Salicylic Acid is also anti-inflammatory, making it especially effective for calming inflamed breakouts. It is commonly found in cleansers, toners, serums, and spot treatments designed for oily or acne-prone skin.

Hyaluronic Acid:

is a humectant, meaning it attracts and binds water to the skin. Naturally found in the body, Hyaluronic Acid helps maintain skin hydration, elasticity, and a plump appearance. It can hold up to 1,000 times its weight in water, helping the skin retain moisture throughout the day. Hyaluronic Acid is an excellent ingredient for all skin types but is especially beneficial for dry or dehydrated skin.

Lactic Acid:

is an AHA naturally derived from milk that provides gentle chemical exfoliation by dissolving the bonds between dead skin cells. It promotes healthy cell turnover while helping to improve skin texture, dullness, uneven pigmentation, and mild congestion. Unlike stronger exfoliating acids, Lactic Acid is generally well tolerated by sensitive skin. It also helps increase the skin's natural ceramide production and improves the skin barrier's ability to retain moisture.

L-Ascorbic Acid:

is the pure and most researched form of Vitamin C used in skincare. It is a powerful antioxidant that helps protect the skin from environmental damage while brightening dull skin, fading pigmentation, stimulating collagen production, and improving the appearance of fine lines. L-Ascorbic Acid works especially well when combined with other antioxidants, such as Vitamin E and Ferulic Acid, for enhanced protection against free radical damage.

Azelaic Acid:

is a naturally occurring acid that is commonly produced synthetically for skincare products. It has antibacterial and anti-inflammatory properties, making it an excellent treatment for acne, rosacea, and post-inflammatory pigmentation. Azelaic Acid helps reduce acne-causing bacteria, calm redness, unclog pores, and fade discoloration. It is suitable for most skin types, including darker skin tones, and is generally considered safe to use during pregnancy and breastfeeding, although it's always best to consult your healthcare provider.

Ferulic Acid:

is a powerful plant-derived antioxidant found in foods such as oats, rice, apples, oranges, and peanuts. It helps neutralize free radicals caused by UV exposure, pollution, and environmental stress before they can damage skin cells. Ferulic Acid is often combined with Vitamins C and E because it enhances their stability and antioxidant effectiveness, providing greater protection against premature skin aging.

Mandelic Acid:

is an AHA derived from bitter almonds. Because it has a larger molecular size than Glycolic Acid, it penetrates the skin more slowly, making it a gentler option for sensitive or reactive skin. Mandelic Acid helps improve uneven texture, acne, pigmentation, and signs of aging while minimizing the risk of irritation. It can also be safely combined with other exfoliating acids in professional treatments.

PHAs (Polyhydroxy Acids):

are the newest generation of chemical exfoliants and are often considered the gentlest alternative to AHAs. Like AHAs, PHAs work by dissolving the bonds between dead skin cells, allowing them to shed more easily and revealing smoother, brighter skin. However, because PHAs have larger molecules, they penetrate the skin more slowly, making them much less likely to cause irritation.

In addition to gentle exfoliation, PHAs also act as humectants, attracting water to the skin and helping strengthen the skin's protective barrier. They improve skin texture, soften the appearance of fine lines, boost hydration, and are an excellent choice for sensitive, dry, mature, or rosacea-prone skin. The most common PHAs found in skincare are Gluconolactone and Lactobionic Acid.

Lactobionic Acid:

is a Polyhydroxy Acid (PHA) that provides gentle exfoliation while helping to hydrate and strengthen the skin. Its large molecular size allows it to penetrate the skin slowly, making it an excellent choice for sensitive, dry, or mature skin. Lactobionic Acid helps smooth rough texture, brighten dull skin, improve the appearance of fine lines, and support the skin's natural barrier. It also has antioxidant properties that help protect the skin from environmental damage, making it especially beneficial for aging and rosacea-prone skin.

Gluconolactone:

is a Polyhydroxy Acid (PHA) that gently exfoliates the skin while attracting and retaining moisture. Because it penetrates the skin more slowly than traditional AHAs, it is less likely to cause irritation, making it suitable for sensitive skin. Gluconolactone helps improve skin texture, even skin tone, minimize the appearance of fine lines, and strengthen the skin's protective barrier. It also provides antioxidant benefits and works well alongside other active ingredients, making it a versatile choice for maintaining healthy, balanced skin.

• Glycolic Acid → texture, pigmentation, signs of aging

• Lactic Acid → dry or sensitive skin

• Salicylic Acid → oily, congested, acne-prone skin

• PHAs → sensitive or compromised skin

• Hyaluronic Acid → hydration for all skin types

Exfoliating Acids

• AHAs

• Glycolic Acid

• Lactic Acid

• Mandelic Acid

Pore-Clearing Acids

• BHAs

• Salicylic Acid

Gentle Exfoliating Acids

• PHAs

• Lactobionic Acid

• Gluconolactone

Hydrating Acid

• Hyaluronic Acid

Brightening & Antioxidant Acids

• L-Ascorbic Acid

• Ferulic Acid

• Azelaic Acid