Guide to Essential Acids in Skincare

By Dr. Kelly Bomer, Facial Plastic Surgeon and Skincare Expert

When it comes to optimizing your skin’s health and appearance, few ingredient groups are as transformative as acids. While the word may sound intimidating, many acids are gentle, skin-friendly molecules that exfoliate, hydrate, brighten, and rejuvenate the skin — all depending on the type used and how it's formulated.

As a Facial Plastic Surgeon and long-time skincare educator, I’ve seen first-hand how the right acid in the right routine can significantly improve acne, fine lines, texture, pigmentation, and overall glow.

Here’s your ultimate guide to essential acids in skincare — how they work, who they’re best for, and how to use them safely and effectively.

1. Alpha Hydroxy Acids (AHAs)

Best for: Dullness, fine lines, uneven texture, sun-damaged skin

AHAs are water-soluble acids typically derived from sugar cane, milk, or fruits. They work by gently dissolving the bonds between dead skin cells on the surface, allowing them to slough off and reveal brighter, smoother skin underneath. Common AHAs:

Glycolic Acid – The strongest and most effective AHA, glycolic acid has the smallest molecular size, allowing it to penetrate deeply. It:

• Stimulates collagen production
• Exfoliates and renews skin
• Improves fine lines, sun damage, and tone

Lactic Acid – Gentler than glycolic acid, lactic acid is great for sensitive or dry skin and also hydrates while exfoliating.

AHAs can also speed up cell turnover, helping the skin renew itself more efficiently, which is especially beneficial in aging or sun-damaged skin.

💡 Tip from Dr. Bomer: AHAs are best used at night and always require daily sunscreen use, as they increase sensitivity to UV light.

2. Beta Hydroxy Acids (BHAs)

Best for: Oily, acne-prone, or congested skin

BHAs are oil-soluble, which makes them uniquely capable of penetrating deep into pores to dissolve excess oil, debris, and sebum — making them ideal for acne and blackhead-prone skin. The standout BHA:

Salicylic Acid – A go-to ingredient for acne, it:

• Unclogs pores
• Reduces inflammation
• Helps fade post-acne marks
• Has mild antibacterial properties

✅ Key Benefit: Because BHAs go deeper into the pore lining, they are more effective than AHAs for treating breakouts and congestion.

3. Polyhydroxy Acids (PHAs)

Best for: Sensitive, dry, or rosacea-prone skin

PHAs are a newer, gentler category of exfoliants. They work similarly to AHAs but have larger molecules, which means they penetrate more slowly and don’t reach as deep — reducing the chance of irritation.

Benefits of PHAs:

• Gentle surface exfoliation
• Hydrating (they attract moisture to the skin)
• Antioxidant-rich
• Suitable for post-procedure or very sensitive skin
  

Common PHAs include gluconolactone and lactobionic acid.

🌿 Dr. Bomer’s Advice: PHAs are an excellent introduction to exfoliating acids or a calming option for those who can’t tolerate traditional AHAs.

4. Hyaluronic Acid (HA)

Best for: All skin types, especially dehydrated or aging skin

Despite its name, hyaluronic acid is not an exfoliating acid. It’s a hydrating molecule naturally found in the skin that attracts up to 1,000 times its weight in water.

What it does:

• Plumps and hydrates skin
• Helps smooth fine lines temporarily
• Enhances the performance of moisturizers and serums
  

💧 Use it under your moisturizer or SPF to lock in hydration and create a healthy, supple skin barrier.

5. Ascorbic Acid (Vitamin C)

Best for: Uneven tone, pigmentation, dullness, prevention of aging

Ascorbic acid is the purest form of Vitamin C, a potent antioxidant that helps:

• Brighten and even skin tone
• Reduce hyperpigmentation and sunspots
• Stimulate collagen synthesis
• Protect against environmental damage
  

It pairs well with Vitamin E and Ferulic Acid, which enhance its stability and antioxidant power.

🌞 Use it in the morning, before sunscreen, to enhance protection against UV and pollution.

6. Other Targeted Acids to Know

Mandelic Acid – A gentle AHA with antibacterial properties; great for combination skin and hormonal acne.

Azelaic Acid – Calms redness, helps treat rosacea and acne, and improves pigmentation without irritation.

Ferulic Acid – A powerful antioxidant that stabilizes Vitamin C and enhances sun protection.

Retinoic Acid (Vitamin A derivatives) – Though often grouped separately, they chemically function like acids. Retinoids help:

• Improve cell turnover
• Treat fine lines, acne, and sun damage
  

Choosing the Right Acid for Your Skin

Every skin type can benefit from the right kind of acid — whether it’s for exfoliation, hydration, brightening, or acne control. The key is understanding how each acid works, starting slowly, and integrating it into a well-rounded routine.

As a plastic surgeon, my recommendation is to consult with a skincare professional when choosing acids, especially if you’re combining multiple actives or have sensitive skin. When used properly, these ingredients can transform skin tone, texture, and health.

Need help choosing the right solution for your skin? Become a Rejuvent Skincare patient for free today and benefit from VIP specials, access to exclusive products, and complimentary access to acne treatment and skin care experts.