How to Strengthen Your Skin Barrier
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Updated September 2026
Quick answer: AHAs (like glycolic and lactic acid) are water-soluble and exfoliate the surface of the skin, so they're best for dryness, dullness and uneven tone. BHAs (mainly salicylic acid) are oil-soluble and get inside pores, so they're best for oily skin, blackheads and breakouts. Combination skin can use both, just not at full strength on the same night.
What's the difference between AHA and BHA?
| Question | AHA | BHA |
|---|---|---|
| Examples | Glycolic, lactic, mandelic, malic, citric | Salicylic acid (also from willow bark and wintergreen) |
| Dissolves in | Water | Oil |
| Works on | Skin's surface | Surface and inside pores |
| Best for | Dry, dull, uneven or sun-damaged skin | Oily, blemish-prone skin and blackheads |
| Sun sensitivity | Increases it. SPF is a must. | Less of an issue, but still wear SPF |
| Bonus | Helps skin hold moisture | Calms inflammation |
What does AHA do?
Alpha hydroxy acids loosen the bonds between dead skin cells on the surface so they shed faster. The result is smoother texture, more even tone and a brighter look. Glycolic acid has the smallest molecule and works fastest. Lactic and mandelic acid are gentler, so they're better for sensitive skin. Here's a breakdown of every AHA.
What does BHA do?
Beta hydroxy acid, almost always salicylic acid, can cut through oil. That means it gets into pores and clears the mix of oil and dead skin that turns into blackheads and breakouts. It also calms redness, which makes it a good match for acne-prone skin.
Which one should you use?
- Dry or dull skin: start with an AHA, such as lactic acid or fruit-enzyme cleansers.
- Oily skin, blackheads or breakouts: start with a BHA.
- Combination skin: use a BHA on your T-zone, or alternate AHA and BHA nights.
- Sensitive skin: choose mandelic acid, lactic acid or a low-strength BHA, and exfoliate just two or three times a week.
Can you use AHA and BHA together?
Yes, and plenty of products combine them at low strengths. What causes trouble is stacking a strong AHA and a strong BHA on the same night. If your skin stings, gets tight or starts peeling, cut back. Always follow with moisturizer, and wear SPF the next morning.
How we use them
Hydraglow Gel Cleanser uses AHAs from pineapple, lemon and grape enzymes for a gentle daily exfoliation that rinses off, with hyaluronic acid and provitamin B5 to keep skin from feeling stripped. Soft Focus Daily Refining Toner uses willow bark, a natural source of salicylic acid, with niacinamide for pores and texture.
Frequently asked questions
How often should you exfoliate with acids?
Two to three times a week is a good start. Gentle, rinse-off formulas can be used daily if your skin tolerates them.
Can you use AHA or BHA with vitamin C?
You can, but it's easier on skin to split them: vitamin C in the morning, acids at night.
Is salicylic acid a BHA?
Yes. It's the most common BHA in skincare. Willow bark and wintergreen are natural sources.
Should you use an exfoliant if your skin barrier is damaged?
No. Pause acids until your skin stops stinging and feeling tight, then bring them back slowly.
