Maltobionic Acid

Maltobionic acid is a polyhydroxy acid (PHA) exfoliant/humectant typically used around ~1–10% in leave-on formulas, generally less stinging than glycolic or lactic acids due to its larger molecular size and slower penetration. However, as an acid active it can still cause transient stinging, erythema, or barrier disruption—especially on eczematous, compromised, or over-exfoliated skin and when layered with other actives. Given real-world cumulative irritation risk in sensitive populations, I rate it as mild rather than fully gentle. Safety Notes: In commercial skincare, maltobionic acid (a PHA) is most often found in leave-on serums/lotions and gentle exfoliating toners at low levels around ~0.1–1% when used as a supporting exfoliant/humectant within multi-acid blends. Dedicated PHA exfoliants marketed for sensitive skin commonly use ~3–10% total PHAs, with maltobionic acid sometimes comprising most of the acid system; high-strength OTC consumer peels/serums have been observed up to about ~12% maltobionic acid equivalent in leave-on formats (typically buffered and pH-controlled). Rinse-off cleansers generally sit toward the lower end due to short contact time, while the upper end is mainly leave-on products where pH, buffering, and stinging potential govern practical limits.