Introduction: Scrubs feel satisfying but your skin doesn’t need sandpaper; it needs strategy. Chemical exfoliants (AHAs, BHAs, PHAs) melt away dull, sticky dead cells, unclog pores, and coach your skin into renewing itself gently. Below, we unpack what they are, how they work, who should use which, and how to plug them into a routine without overdoing it.
Exfoliation 101: What’s Actually Happening on Your Skin
Your outermost layer (stratum corneum) is like roof shingles held together by “glue” (corneodesmosomes + lipids). With age, stress, UV, and pollution, this glue gets stubborn. Chemical exfoliants loosen it so fresh, even-toned skin can surface no micro-tears, no over-scrubbing. Bonus: a smoother canvas lets your sunscreen and actives (like vitamin C and hyaluronic acid) work better.
| Type | How it works | Pros | Watch-outs |
|---|---|---|---|
| Chemical (AHAs/BHAs/PHAs) | Dissolve bonds between dead cells; BHA also clears inside pores | Even, controlled, less barrier trauma; targets tone/texture/acne | Overuse → irritation; needs SPF diligence |
| Physical (scrubs/brushes) | Manually abrades surface cells | Immediate feel; simple | Micro-tears, barrier disruption if harsh or too frequent |
Meet the Acids: AHAs, BHAs, and PHAs (Who Needs What)
- AHAs (water-soluble): Glycolic (small, potent), Lactic (gentler, hydrating), Mandelic (larger, great for sensitive or pigmentation-prone). Best for tone, fine lines, dullness, dryness.
- BHA (oil-soluble): Salicylic acid dives into pores, dissolves sebum + debris, and is anti-inflammatory. Best for blackheads, whiteheads, visible pores, and acne-prone or oily skin.
- PHAs (big, slow, kind): Gluconolactone, Lactobionic acid offer AHA-like smoothing with extra humectant and antioxidant perks. Best for sensitive, impaired barriers, or retinoid users wanting a gentler buff.
What the Science Says
Texture & tone: AHAs increase cell turnover and can stimulate dermal glycosaminoglycans and collagen over time, improving fine lines and roughness in photoaged skin. Lactic acid also boosts hydration thanks to its humectant nature.
Acne & pores: Salicylic acid penetrates the pore lining (lipophilic), exfoliates inside the pore, and calms inflammation reducing comedones and inflammatory lesions. It’s a first-line adjunct in many acne routines.
Sensitivity options: PHAs deliver smoothing and antioxidant effects with lower sting potential, making them suitable for reactive skin and for pairing with retinoids or post-procedure (per clinician guidance).
Barrier considerations: Over-exfoliation impairs lipids and tight junctions; gentle, paced use preserves barrier while delivering glow. Always pair acids with broad-spectrum SPF to protect newly refined skin.
How to Build Your Acid Routine (Without Angry Skin)
- Pick one primary acid based on your goal:
- Glow & texture: 5–10% lactic or 5% mandelic, 2–4 nights/week.
- Pores & breakouts: 0.5–2% salicylic, daily or QOD as tolerated.
- Advanced tone/lines: 5–8% glycolic 2–3 nights/week (start low).
- Ultra-sensitive: PHAs 3–5 nights/week.
- Patch test: 24–48 hours on the jawline/behind ear.
- Apply on clean, dry skin at night. Then buffer with a simple moisturizer (look for ceramides, glycerin, squalane).
- Don’t stack too many actives. Avoid layering strong retinoids, high-% vitamin C (LAA), and other acids in the same session early on. Alternate nights.
- SPF daily. Exfoliation increases photosensitivity broad-spectrum SPF 30+ every morning, reapply outdoors.
| Concern | Go-to acid | Starter frequency | Pair with |
|---|---|---|---|
| Dullness, fine lines | Lactic 5–10% or Glycolic 5–8% | 2–3×/week (PM) | Hyaluronic acid serum, rich moisturizer |
| Blackheads, breakouts | Salicylic 0.5–2% | Daily or QOD | Niacinamide, lightweight SPF gel |
| Blotchiness, sensitivity | PHAs 3–8% | 3–5×/week | Ceramides, panthenol |
| Hyperpigmentation | Mandelic/Lactic + spot azelaic 10% | 3×/week acids; azelaic daily | Daily mineral SPF, vitamin C AM |
Practical Tips
- Less is more: A pea-sized amount or thin layer is enough for face and neck.
- Zone application: BHA on T-zone only; AHA/PHAs cheeks and forehead if you’re combo.
- Moisture sandwich: If you’re sensitive, apply a thin moisturizer layer, then acid, then moisturize again.
- Seasonal tweaks: Dial down acids in winter or after sun exposure; up your barrier care.
- Pair smartly: AM vitamin C for antioxidant defense, PM acids for renewal, nightly HA for hydration.
Risks & Who Should Be Careful
Over-exfoliation signs: tightness, stinging, flaking, sudden sensitivity. Pause acids, use bland barrier repair (ceramides, petrolatum), and SPF. Reintroduce slowly.
Avoid/consult first if: you’re pregnant (limit salicylic/strong acids ask your clinician), have eczema/rosacea flares, active barrier damage, open wounds, recent procedures, or are on prescription acne/retinoid therapy coordinate with your dermatologist.
This article is educational and not medical advice.
Summary
- AHAs/BHAs/PHAs work differently: choose by skin type and goal.
- Start low, go slow, moisturize generously, and wear SPF daily.
- Consistency beats strength: gentle, regular use delivers brighter, smoother skin.
Sources: NIH & dermatology texts; peer-reviewed journals incl. Dermatol Surg, J Am Acad Dermatol, J Clin Aesthet Dermatol, J Eur Acad Dermatol Venereol. Educational only; not medical advice.
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