Unlocks exact minute-by-minute pH buffer wait times, 4-night skin-cycling calendar & barrier-safe swaps
Paula's Choice 2% BHA Liquid Exfoliant Layering Guide: pH 3.5 Conflicts & Malassezia Check
Cult pH 3.5 oil-soluble 2% Salicylic Acid desmolytic. Note: contains Polysorbate 20 (Malassezia trigger).
Recommended Spacing: 15 Minutes
Apply in the AM only if paired with broad-spectrum SPF 30–50+ and separated from antagonistic pH/redox actives.
In the PM, Do not layer in the same session with Tretinoin, Retinol, Glycolic Acid, or Copper Peptides. Note: contains Polysorbate 20 (flagged for fungal acne).
Layering low-pH keratolytic acids (pH 3.0–3.8) with nuclear retinoids strips the stratum corneum barrier, accelerates acid-catalyzed retinoid degradation, and causes severe retinoid dermatitis.
Direct acids (pH < 4.0) protonate the imidazole nitrogen of histidine in Copper Tripeptide-1, breaking the copper coordination bond and hydrolyzing peptide chains.
Applying pH 3.5 acid alongside neutral oligopeptides (ΔpH 2.7 > 1.8 threshold) denatures peptide conformation and cleaves matrikine bonds.
+ View 4 additional secondary ingredient interaction(s)
Applying pH 3.5 acid alongside neutral oligopeptides (ΔpH 2.7 > 1.8 threshold) denatures peptide conformation and cleaves matrikine bonds.
Co-layering 1% Copper Tripeptide-1 and potent retinoids in the same PM session increases stinging and risks trace Cu2+ acceleration of retinoid isomerization.
Applying pH 3.5 acid alongside neutral oligopeptides (ΔpH 2.7 > 1.8 threshold) denatures peptide conformation and cleaves matrikine bonds.
Applying pH 3.5 acid alongside neutral oligopeptides (ΔpH 2.7 > 1.8 threshold) denatures peptide conformation and cleaves matrikine bonds.
- AM Prep: pH 5.5 Gentle Amino-Acid Cleanser or Water Rinse [pH 5.5 · Pat dry]
- AM Peptide Remodeling: Copper Tripeptide-1 (GHK-Cu) 1% Serum (Separated from PM Acids/Retinoids) [pH 6.2 · Apply on damp skin]
- AM Barrier + Photoprotection: Physiological Ceramide Moisturizer + Broad-Spectrum SPF 50+ PA++++ [pH 5.8 · Mandatory final step]
Save Your Personalized AM/PM Glow Ritual & 9:16 Vanity Card
Includes your printable 4-Night Skin-Cycling calendar, Henderson-Hasselbalch free-acid table, and Apple-Wallet lockscreen guide.
Esthetician & Cosmetic Chemist FAQ
What is the formulation pH and full INCI profile of Paula's Choice Skin Perfecting 2% BHA Liquid Exfoliant?
Paula's Choice Skin Perfecting 2% BHA Liquid Exfoliant is formulated at pH 3.5 ($35). Full INCI: Water (Aqua), Methylpropanediol, Butylene Glycol, Salicylic Acid, Polysorbate 20, Camellia Oleifera (Green Tea) Leaf Extract, Sodium Hydroxide, Tetrasodium EDTA.
Which skincare actives conflict with Paula's Choice Skin Perfecting 2% BHA Liquid Exfoliant?
Do not layer in the same session with Tretinoin, Retinol, Glycolic Acid, or Copper Peptides. Note: contains Polysorbate 20 (flagged for fungal acne).
Is Paula's Choice Skin Perfecting 2% BHA Liquid Exfoliant comedogenic or fungal-acne (Malassezia) safe?
Run the pre-loaded INCI analyzer above to inspect positional comedogenicity (0–5) and C12–C24 Malassezia lipid ester triggers for every ingredient in Skin Perfecting 2% BHA Liquid Exfoliant.