A Guide to Alpha Hydroxy Acid (AHA) Exfoliants in Skincare
Alpha Hydroxy Acids (AHAs) are a popular category of chemical exfoliants that work wonders for brightening, smoothing, and revitalizing the skin. These water-soluble acids help to slough off dead skin cells, unclog pores, and improve skin texture, making them a staple in many skincare routines. From glycolic acid to lactic acid, AHAs come in several varieties, each offering unique benefits for different skin types and concerns. Let’s take a closer look at the most common AHAs and how they can benefit your skincare regimen.
What Are Alpha Hydroxy Acids?
AHAs are a group of naturally occurring acids derived from fruits, milk, and other plant sources. They are primarily known for their exfoliating properties, but they also have the ability to hydrate, reduce hyperpigmentation, and promote collagen production, making them multi-functional ingredients in skincare products. AHAs work by dissolving the bonds that hold dead skin cells together on the surface, allowing new, fresh skin to emerge. This process promotes cell turnover and can improve the appearance of fine lines, acne scars, and overall skin texture.
1. Glycolic Acid
Source: Derived from sugarcane
Molecular Size: Small (penetrates deeply)
Best For: All skin types. Sensitive skin proceed with caution.
Benefits:
Powerful exfoliant: Glycolic acid is the most well-known and commonly used AHA because of its small molecular structure, which allows it to penetrate the skin deeply and exfoliate effectively.
Anti-aging: It helps reduce the appearance of fine lines and wrinkles by stimulating collagen production and improving skin elasticity.
Brightening: Regular use can help fade dark spots, acne scars, and uneven skin tone.
How to Use: Glycolic acid can be found in toners, serums, masks, and cleansers. However, due to its potency, it's important to start with lower concentrations (around 5-10%) and gradually increase as your skin builds tolerance.
2. Lactic Acid
Source: Derived from milk or fermented plants
Molecular Size: Larger than glycolic acid (gentler)
Best For: Sensitive, dry, or dull skin. Those with deeper skin tones.
Benefits:
Gentler exfoliation: Lactic acid has a larger molecular structure, which means it exfoliates more slowly and is less likely to irritate sensitive skin compared to glycolic acid.
Hydrating: Unlike other AHAs, lactic acid has humectant properties, meaning it helps to attract moisture into the skin, making it ideal for dry or dehydrated skin types.
Even skin tone: It helps to brighten and reduce the appearance of pigmentation, including sunspots and age spots.
How to Use: Lactic acid can be found in products formulated specifically for dry or sensitive skin. Start with lower concentrations (around 5%) and use it in the evening to allow your skin to adjust.
3. Mandelic Acid
Source: Derived from almonds Molecular Size: Large (gentle) Best For: Sensitive skin, acne-prone skin, hyperpigmentation Benefits:
Gentler exfoliant: Due to its large molecular size, mandelic acid exfoliates the skin more gently than glycolic acid, making it a great option for those with sensitive or reactive skin.
Acne-fighting: Its antibacterial properties help fight acne-causing bacteria, making it ideal for individuals with acne-prone skin.
Improves skin tone: Mandelic acid is effective at fading dark spots and hyperpigmentation, and can help even out skin tone without irritation.
How to Use: Mandelic acid is typically found in serums. It’s well-suited for sensitive skin types and can be used up to everyday, depending on tolerance.
4. Azelaic Acid
Source: Derived from grains such as barley, wheat, and rye Molecular Size: Medium Best For: Acne-prone skin, rosacea, pigmentation issues Benefits:
Anti-inflammatory: Azelaic acid has anti-inflammatory properties that help reduce redness, making it especially useful for conditions like rosacea and acne.
Fights acne: It helps to reduce the growth of acne-causing bacteria and clear clogged pores, making it an effective treatment for both active breakouts and acne scars.
Brightening and pigmentation: Azelaic acid helps to fade dark spots, melasma, and post-inflammatory hyperpigmentation, and it can also improve skin texture.
How to Use: Azelaic acid is available in both prescription-strength formulations (usually 15-20%) and over-the-counter options (typically around 10%). It can be used daily, but it’s best to start with 2-3 times per week and gradually build up to daily use.
5. Polyhydroxy Acid (PHA)
Source: Derived from fruit and milk sugars (lactobionic acid, gluconolactone)
Molecular Size: Larger than AHAs, more gradual
Best For: Sensitive skin, dry skin, or skin with a compromised barrier
Benefits:
Very gentle exfoliation: PHAs have a much larger molecular size compared to AHAs, meaning they exfoliate more slowly and with less irritation. This makes them ideal for individuals with sensitive or reactive skin.
Hydrating: PHAs have excellent humectant properties, which help to draw moisture into the skin, making them ideal for dry and dehydrated skin.
Antioxidant-rich: PHAs are packed with antioxidants, helping to protect the skin from oxidative stress and environmental damage.
Ideal for barrier repair: PHAs can strengthen the skin’s moisture barrier, making them beneficial for skin that is prone to dryness, irritation, or conditions like eczema and rosacea.
How to Use: PHAs are often found in gentle exfoliants, toners, and moisturizers. They can be used daily and are great for those new to chemical exfoliation or those with sensitive skin.
How to Choose the Right AHA for Your Skin
Sensitive skin: Lactic acid, mandelic acid, azelaic acid, and PHAs are the gentlest options and are ideal for those with sensitive skin. These acids provide effective exfoliation without causing significant irritation.
Oily or acne-prone skin: Mandelic acid and azelaic acid are great for targeting excess oil production, acne breakouts and reduce pigment and acne scars.
Aging skin: Glycolic acid and lactic acid are the best choices for improving the appearance of fine lines and wrinkles, as they stimulate collagen production and promote smoother skin texture.
Dry skin: Lactic acid, mandelic acid, and PHAs are great options for dry skin, as they provide gentle exfoliation while helping the skin retain moisture.
How to Use AHAs Safely
Start slow: When incorporating AHAs into your skincare routine, start with a product containing a lower concentration (around 5-10%) to allow your skin to build tolerance.
Use sunscreen: AHAs can make your skin more sensitive to UV rays, so always wear sunscreen during the day to protect your skin from sun damage.
Don’t over-exfoliate: Over-exfoliating can lead to irritation, redness, and sensitivity. It’s usually recommended to exfoliate with AHAs 2-3 times per week, depending on your skin’s tolerance.
Patch test: Always perform a patch test on a small area of skin to ensure you don’t have any adverse reactions, especially if you have sensitive or reactive skin.
Alpha Hydroxy Acids are a versatile and effective category of exfoliants that can benefit nearly every skin type. Whether you’re looking to brighten a dull complexion, reduce fine lines, or improve skin texture, there’s an AHA that can work for you. Choosing the right AHA depends on your skin type, concerns, and sensitivity levels, so it's always a good idea to start with a patch test and gradually increase usage to see how your skin responds. With regular use and proper sun protection, AHAs can be a powerful ally in achieving healthier, smoother, and more radiant skin.
