The Acid Layering Guide: AHA, BHA, PHA across origins
Glycolic, lactic, mandelic, salicylic, polyhydroxy — six exfoliating acid families with different penetration depths, irritation profiles, and use cases. Here's the cross-origin layering and routing guide.
Ask ChokChok AI
Get instant answers about "The Acid Layering Guide: AHA, BHA, PHA across origins"
Try asking
Six families, different jobs
The "exfoliating acids" category is six distinct chemical families, each with different penetration profiles and clinical use cases. Confusing them is the root of most acid-skincare mistakes.
1. Glycolic acid (AHA, sugarcane-derived). Smallest molecule in the AHA family. Penetrates deepest. Strongest resurfacing effect. Most irritation potential. Best for textured skin, photoaging, post-acne scarring.
2. Lactic acid (AHA, milk-derived). Larger molecule than glycolic. Less penetration, less irritation. Hydrating effect alongside exfoliation. Best for sensitive-but-textured skin or gentle resurfacing.
3. Mandelic acid (AHA, almond-derived). Largest molecule in the AHA family. Slowest penetration, least irritation. Best for very sensitive skin, darker skin tones (lower PIH risk), and acne-prone skin (gentler than salicylic).
4. Salicylic acid (BHA, willow-bark-derived). Oil-soluble — the only one that can penetrate sebum-filled pores. Best for blackheads, whiteheads, and inflammatory acne.
5. Polyhydroxy acids (PHA — gluconolactone, lactobionic acid). Very large molecules. Surface-only exfoliation. Most-tolerable acid family. Best for daily-use sensitive skin or as a step-up from no-acid routine.
6. Azelaic acid (technically dicarboxylic, but functions as gentle exfoliant). Anti-inflammatory + tyrosinase-inhibiting. Best for rosacea, melasma, and post-inflammatory hyperpigmentation. Pregnancy-safe (see Pregnancy-Safe Skincare).
Glycolic acid (most-cited resurfacing)
The Ordinary Glycolic Acid 7% Toning Solution — Disclosed 7% in toner format. Daily-use entry.
Pixi Glow Tonic — 5% glycolic toner. American mass-market default.
Mario Badescu Glycolic Foaming Cleanser — Cleanser format reduces contact time, suits sensitive skin.
Alpha-H Liquid Gold — Australian 5% glycolic evening treatment (decoded here).
Minimalist Glycolic 7% Toning Solution — Indian D2C disclosed concentration.
Caudalie Glycolic Peel Mask — French weekly mask format.
Collistar Pure Actives Glycolic Acid Peeling — Italian pharmacy weekly peel.
Miamo Skin Refresh Glycolic Acid 10% Peel — Italian clinic-strength at-home.
Lactic acid (gentler resurfacing + hydration)
Sunday Riley Good Genes — American prestige reference. Lactic + arnica + licorice. (Decoded here)
The Ordinary Lactic Acid 10% + HA — Disclosed 10% with hyaluronic pairing.
The Ordinary Lactic Acid 5% + HA — Gentler entry tier.
Mandelic acid (sensitive-skin AHA)
By Wishtrend Mandelic Acid 5% Skin Prep Water — Korean disclosed concentration.
Salicylic acid (pores and acne)
Paula's Choice 2% BHA Liquid Exfoliant — American disclosed-concentration reference.
Cosrx BHA Blackhead Power Liquid — Korean accessible-tier reference.
Stridex Maximum Strength — American budget pad format.
Minimalist Salicylic Acid 2% Serum — Indian D2C disclosed concentration.
The Derma Co 2% Salicylic Acid Daily Foaming Face Wash — Indian acne cleanser.
Pilgrim 2% Salicylic Acid Face Serum — Indian alternative.
The Ordinary Salicylic Acid 2% Solution — Disclosed 2%.
PHA (ultra-gentle daily)
The Ordinary AHA 30% + BHA 2% Peeling Solution — High-strength weekly use; not PHA but referenced for high-strength comparison.
Minimalist PHA + Polyglutamic Acid Toner — Indian D2C PHA daily toner.
Karmameju Deep PHA Peeling Mask — Danish PHA mask.
Madara Brightening AHA Peel Mask — Latvian organic AHA-PHA hybrid.
Multi-acid blends
Minimalist AHA-PHA-BHA Peeling Solution — Indian disclosed multi-acid weekly.
The Derma Co 15% AHA + 1% BHA Peeling Solution — Indian high-strength weekly.
MartiDerm DSP-Bright Peeling Solution — Spanish overnight multi-acid + tranexamic.
Azelaic acid (rosacea, melasma, pregnancy-safe)
The Ordinary Azelaic Acid Suspension 10% — Disclosed 10% reference.
Collistar Attivi Puri Azelaic Acid Mask — Italian weekly mask format.
Tirtir Azelaic Acid Serum — Korean accessible-tier.
Layering rules
Don't combine glycolic + retinol on the same night. Use on alternating nights — e.g., retinol Monday/Wednesday/Friday, glycolic Tuesday/Thursday, rest weekends.
Don't combine glycolic + vitamin C in one application. They can work in opposing pH ranges. Use VC in the morning, AHA at night.
Salicylic acid is more flexible. Can be used daily without conflicting with most actives. Compatible with niacinamide, peptides, ceramides.
PHA is the most-flexible. Daily use without restriction. Compatible with everything.
Always SPF50 the next morning after acid use. Acids increase photosensitivity for 7-14 days.
Start frequency low, build up. First 2 weeks: 2 nights/week. Build to 3-4 nights/week. Don't push to nightly unless tolerance is established.
When to skip acids entirely
- Active eczema or rosacea flares. Acids worsen inflammation in active flares.
- Compromised barrier. Repair the barrier first (see ceramide guide).
- Pregnancy and breastfeeding. Salicylic acid is contraindicated; AHAs are debated. Stick to azelaic and glycolic at low concentrations or skip entirely.
- Recent retinoid prescription. Tretinoin already provides exfoliation; layering acids drives irritation.
The bottom line
Match acid family to concern. Match concentration to tolerance. Layer with intention, not enthusiasm. Always SPF50 in the morning. Build up slowly. The visible results from disciplined acid use are real but require 8-12 weeks of consistency to show.
Keep Reading
Alpha-H Liquid Gold: how a Brisbane chemist's glycolic acid put Australia on the global skincare map
Alpha-H launched in 1995 in Brisbane, Australia, founded by skin-and-cosmetic chemist Michelle Doherty. The brand's signature product, Liquid Gold (a 5% glycolic acid evening treatment with silk amino acids and licorice extract), became Australia's most-cult skincare product and proved to global skincare consumers that AHA exfoliation could be both clinically effective and aesthetically luxurious.
Why Australian night skincare hits different: UV damage control meets botanical innovation
Australia's extreme UV environment creates a skincare market where overnight repair isn't optional — it's medical-grade damage control. We examine how Aesop, Alpha-H, Emma Lewisham, Grown Alchemist, and KORA Organics each approach the problem, from acid-forward resurfacing to botanical regeneration, and rank the overnight treatments worth adding to your routine.