active
Hypochlorous Acid (HOCl)
The unlikely crossover ingredient of 2025: a molecule produced by the immune system's white blood cells, migrated from wound care and post-procedural disinfection into mainstream clean skincare. Kills bacteria, viruses, and fungi without disrupting the barrier — non-cytotoxic, non-sensitizing, safe even for babies and post-procedure skin. Tower 28's SOS Daily Rescue Facial Spray made it viral.
Benefits
- antibacterial without barrier disruption
- non-sensitizing across all skin types
- safe post-procedure and on compromised skin
Example uses
- face mists
- post-procedure sprays
- acne-prone and sensitive-skin rescue
Mechanism of action
A small (52 Da), endogenous oxidant produced by neutrophil and eosinophil myeloperoxidase as part of the innate immune response. It penetrates microbial cell membranes and oxidatively destroys microbial proteins, lipids, and DNA via chlorination — the same mechanism the immune system uses internally. Critically, mammalian cells with intact antioxidant systems and membrane chemistries are largely unaffected at the dilute concentrations used cosmetically (0.01–0.02%) — the basis for its non-cytotoxic, non-sensitising profile. Distinct from sodium hypochlorite (bleach) by pH and equilibrium chemistry: HOCl is the active, neutral, undissociated form.
Clinical evidence · High
Strong wound-care, ophthalmology, and post-procedure literature; FDA-cleared (510(k)) for multiple medical-device indications; cosmetic-skincare clinical work is newer but consistent.
Effective concentration range
0.01–0.02% (pH 4.5–6 for stability)
Formulation notes
Effective at 0.01–0.02%. Free of synthetic preservatives, parabens, alcohol, and fragrance.
Watchouts
Inherently unstable — poorly manufactured HOCl degrades rapidly. Quality-tier divide is wide; favor brands with documented stability data.
Controversies & overclaims
Stability is the entire honesty question: HOCl is in equilibrium with hypochlorite and chlorine gas, and pH drift in poorly manufactured product causes rapid loss of the active fraction. Quality-tier divide is wide; favour brands publishing stability data and using purpose-designed containers. 'Tougher than chlorine but gentler than water' marketing is overstated.
Market positioning
The 2025 crossover from wound-care to mainstream skincare — Tower 28 SOS Spray anchored the consumer awareness; medical-grade Briotech and SkinSmart predate the cosmetic positioning by years. Real value is significant for sensitive, post-procedure, and acne-prone skin; the long-term place on a standard routine is still being negotiated.
Comedogenicity
0 / 5
Sensitisation risk
Low
INCI & aliases
Hypochlorous Acid
Clean beauty perception
Strongly positive — proof point that 'gentle' and 'effective' are not opposites.
Related ingredients
Graph relationships
Timeline