In This Article:
- The Two Categories: AHA vs BHA
- Glycolic Acid: The Deep Resurfacer
- Salicylic Acid: The Pore Cleaner
- Lactic Acid: The Gentle Hydrator
- Which Acid Is Right for Your Skin?
- Can You Use All Three Together?
- FAQ
Skincare acids are confusing. Walk into any store and you'll see glycolic, salicylic, lactic, mandelic, azelaic and that's before you even get to the retinoids. No wonder people feel overwhelmed!
Let me simplify this. After 15 years of working with these ingredients on real clients' skin, I've learned that most people only need to understand three acids. Here's your simplified and complete guide:
The Two Categories: AHA vs BHA
First, the foundation. All skincare acids fall into two families:
AHAs (Alpha Hydroxy Acids): Water-soluble. These work on the surface of your skin. Best for dullness, texture, dark spots, and fine lines. Glycolic and lactic acid are both AHAs.
BHAs (Beta Hydroxy Acids): Oil-soluble. These penetrate inside your pores. Best for acne, blackheads, and oily skin. Salicylic acid is the main BHA.
This oil-soluble vs water-soluble distinction is the most important thing to understand. AHAs work on top. BHA works inside.
Glycolic Acid: The Deep Resurfacer
What it is: The smallest AHA molecule, derived from sugarcane.
What it does: Because it's so small, glycolic acid penetrates deeper than other AHAs. It dissolves the "glue" (desmosomes) holding dead skin cells together, allowing them to shed faster and reveal fresher skin underneath.
Best for:
- Dullness and rough texture
- Fine lines and wrinkles
- Uneven skin tone
- Sun damage and dark spots
- Overall radiance
Concentration guide:
- 5-10%: Daily use in cleansers and toners
- 10-20%: Weekly treatments
- 20-70%: Professional peels only
Caution: Glycolic acid increases sun sensitivity. SPF is mandatory when using it.
Salicylic Acid: The Pore Cleaner
What it is: A BHA derived from willow bark.
What it does: Salicylic acid is oil-soluble, which means it can dissolve through the sebum inside your pores. While AHAs clean the surface, salicylic acid goes inside your pores and cleans them from within.
Best for:
- Acne and breakouts
- Blackheads and whiteheads
- Enlarged pores
- Oily skin
- Congested skin
Concentration guide:
- 0.5-2%: Daily use in cleansers and treatments
- 2%: Maximum over-the-counter concentration
Why it's special: It also has anti-inflammatory properties, which means it fights breakouts AND calms the redness around them.
Lactic Acid: The Gentle Hydrator
What it is: An AHA derived from milk (though modern versions are synthetic).
What it does: Lactic acid exfoliates like glycolic acid but with a larger molecule, so it works more gently on the surface. It also has a unique bonus: it's a natural humectant, meaning it attracts and holds moisture.
Best for:
- Sensitive skin that can't tolerate glycolic
- Dry skin that needs exfoliation + hydration
- First-time acid users
- Hyperpigmentation
- Rough texture with dehydration
Concentration guide:
- 5%: Gentle daily use
- 10%: Moderate exfoliation
- 10%+: Professional treatments
Which Acid Is Right for Your Skin?
- Acne / blackheads - Salicylic acid
- Dullness / texture - Glycolic acid
- Dry + rough skin - Lactic acid
- Anti-aging - Glycolic acid
- Sensitive skin - Lactic acid
- Oily + congested - Salicylic acid
- All of the above - A triple-acid formula
Can You Use All Three Together?
Yes - when they're formulated correctly. This is exactly why I created the Bright & Early Triple Acid Cleanser. It combines glycolic acid (deep resurfacing), salicylic acid (pore cleaning), and lactic acid (gentle hydrating exfoliation) in one product.
The key is balance. In a cleanser format, the acids have controlled contact time (60 seconds of massage, then rinse), so you get the benefits of all three without the irritation risk of leaving them on all day.
This triple-acid approach means you don't have to choose between acids. You get surface exfoliation, pore cleaning, AND hydration in one step!
Frequently Asked Questions
Can I use acids every day?
In a cleanser format (rinse-off), most people can use acids daily. In a leave-on format (serums, toners), start with 2-3x per week and build up.
Can I use acids with retinol?
Yes, but not at the same time. Use acids in the morning and retinol at night, or alternate nights. Using both simultaneously can damage your barrier.
Do acids thin your skin?
No, this is a common myth. Acids remove dead cells from the surface, but they actually stimulate collagen production in the deeper layers, making skin thicker and stronger over time.
I tried glycolic acid and it burned. Is my skin too sensitive?
Not necessarily. You may have started with too high of a concentration, or your barrier was already compromised. Try lactic acid first, or use glycolic in a cleanser (shorter contact time) rather than a leave-on product.
Denise Bell is a licensed esthetician with over 15 years of experience and the founder of 5 Circle Skin Care in Austin, Texas.