Hypochlorous Acid (HOCl) is a weak acid and potent oxidant produced naturally by the human immune system. When the body detects bacterial infection or tissue damage, neutrophils and macrophages generate HOCl via the enzyme myeloperoxidase — using hydrogen peroxide and chloride ions as substrates. This endogenous production is the body's first-line rapid-response antimicrobial system, capable of destroying a wide spectrum of pathogens within seconds.
In cosmetic science, HOCl has been electrochemically synthesised at controlled concentrations and pH for application on skin. At the low concentrations used in cosmetics (100–500 ppm), HOCl retains its antimicrobial and anti-inflammatory properties while exhibiting a safety profile that is exceptionally compatible with sensitive and compromised skin — a direct consequence of its identity as an endogenous human molecule.
Unlike traditional preservatives or antimicrobial actives (benzalkonium chloride, triclosan, benzoyl peroxide), HOCl does not disrupt the skin microbiome selectively or cause systemic sensitization. It works by transiently disrupting microbial cell membranes and interfering with their enzymatic systems, while leaving commensal organisms largely unaffected at cosmetic concentrations.
HOCl's antimicrobial activity operates through oxidative mechanisms. At physiological concentrations, it oxidises thiol groups in bacterial proteins, disrupts membrane integrity, and interferes with cellular respiration — resulting in rapid bacterial killing. Against S. aureus, P. acnes (C. acnes), E. coli, and Candida species, HOCl demonstrates MIC values in the range of 10–100 ppm, well within its typical cosmetic use window.
Its anti-inflammatory mechanism is less well understood but is thought to involve modulation of NF-κB signalling pathways, downregulation of pro-inflammatory cytokines including IL-1β, IL-6, and TNF-α, and reduction in mast cell degranulation. This dual antimicrobial and anti-inflammatory profile is rare among cosmetic actives and makes HOCl particularly well-suited to reactive, acne-prone, post-procedure, and sensitive skin formulations.
HOCl is not a foreign chemical — it is a molecule the human body already produces. This endogenous identity is the basis for its exceptional tolerability profile, even on the most sensitive and compromised skin.
Hypochlorous Acid has accumulated a robust evidence base across wound care, dermatology, and cosmetic applications over the past two decades. Much of the early clinical data originated from wound care and post-surgical settings, where HOCl demonstrated superior tolerability compared to povidone-iodine and chlorhexidine while maintaining comparable antimicrobial efficacy.
In 2020, a split-face clinical study in acne applications demonstrated that 0.01% HOCl, applied twice daily for 8 weeks, reduced inflammatory lesions by 49% compared to 23% with a vehicle control. Notably, there were no reports of stinging, peeling, or photosensitization typically associated with traditional acne treatments.
Multiple studies across post-procedure and eczema management contexts have corroborated its tolerability profile. HOCl has been shown to reduce TEWL in compromised barrier conditions, suppress staphylococcal colonization in atopic skin, and accelerate re-epithelialization following aesthetic procedures — all without triggering the sensitization or resistance patterns associated with antibiotic-based approaches.
| INCI Name | Hypochlorous Acid |
| CAS Number | 7790-92-3 |
| EC Number | 232-232-5 |
| Molecular Formula | HOCl |
| Molecular Weight | 52.46 g/mol |
| Appearance | Clear, colourless aqueous solution |
| Solubility | Miscible with water; aqueous solution only |
| pH Stability Range | 4.5 – 5.5 (optimal free HOCl form) |
| Recommended Usage | 100 – 500 ppm (cosmetic applications) |
| Origin / Source | Electrolysis of salt water or chemical synthesis |
| Shelf Life | 12 months unopened, cool/dark storage |
| Regulatory Status | CosIng listed | EU Biocidal Product Regulation | FDA GRAS for food contact | CDSCO compliant |
HOCl's safety profile is underpinned by its identity as an endogenous human molecule, making it uniquely compatible with skin physiology.
| Sensitization | Non-sensitizing — no documented HRIPT reactions at cosmetic use levels |
| Comedogenicity | Non-comedogenic |
| Photosensitivity | Non-photosensitizing |
| Irritation Potential | Non-irritating at cosmetic concentrations — used on open wounds and post-procedure skin |
| Microbiome Impact | Minimal disruption to commensal organisms at 100–500 ppm; transient activity only |
| Special Populations | Suitable for sensitive, atopic, and post-procedure skin; used in baby care products |
HOCl is an aqueous active supplied as a ready-to-use solution. It is incorporated directly into finished formulations at dilution — it cannot be meaningfully dried, powdered, or encapsulated for standard cosmetic use. Stability is the primary formulation challenge: HOCl degrades over time, particularly at elevated pH, high temperatures, and under UV exposure.
Antimicrobial action against C. acnes without the irritation of benzoyl peroxide or antibiotics
Soothes compromised skin post-laser, peel, microneedling, or waxing
Gentle antimicrobial toning for reactive, rosacea-prone, or eczema-prone skin
Ultra-gentle cleansing and soothing for infant skin and nappy area care
Supports skin barrier recovery and reduces microbial burden on minor wounds
Blepharitis management; lash line cleansing; ophthalmic-adjacent products
Antimicrobial rinses and lip care products leveraging HOCl's mucosal safety
Reduces scalp microbial load in seborrheic or acne-prone scalp conditions
Must maintain a pH range of 4 to 6, preferably 4.5 to 5.5, to ensure optimal stability and performance. For pH adjustment, use citric acid or lactic acid rather than mineral acids. Monitor pH with a calibrated meter, as HOCl can give inaccurate readings on indicator strips.
| Minimum Efficacious | 100 ppm (0.01% w/w) |
| Typical Range | 200 – 300 ppm (most cosmetic applications) |
| Maximum Practical | 500 ppm (0.05% w/w) for cosmetic applications |
| Parameter | Recommendation |
|---|---|
| Temperature | Store and formulate at ≤25°C. Avoid heating — HOCl degrades rapidly above 40°C. |
| Light | Use opaque or UV-blocking packaging. UV radiation accelerates HOCl decomposition. |
| Container | Use HDPE or glass. Avoid metal containers — HOCl is mildly corrosive to certain metals. |
| Mixing | Add HOCl last, post-emulsification, once the formulation has cooled. Avoid vigorous agitation. |
| Incompatibilities | Do not combine with reducing agents, strong acids (<pH 3), or high-concentration ethanol (>20%) — all accelerate decomposition. |
A cosmetic-grade Hypochlorous Acid solution carried in Centella Asiatica Leaf Extract, stabilised at pH 4.5–5.5 for maximum free HOCl availability. Manufactured at our Jaipur facility with 12-month shelf life. Ideal for acne, post-procedure, sensitive skin, and baby care formulations.
HOCl holds regulatory acceptance across key cosmetic markets. Note that HOCl may fall under both cosmetic and biocide regulations depending on intended use — formulation category should be clearly defined at the outset.
Compliant with Indian Cosmetic Rules 2020. Permitted for topical cosmetic use. No concentration restrictions documented for cosmetic applications at 100–500 ppm.
Listed in the CosIng database. Products with primary disinfectant claims may require registration under the EU Biocidal Products Regulation (BPR 528/2012) — cosmetic claims are assessed separately.
FDA GRAS status for food contact applications. Widely used in dermatological and cosmetic products. No restrictions for topical cosmetic use at concentrations of 100–500 ppm.
Hypochlorous Acid is listed in the Inventory of Existing Cosmetic Ingredients in China. Suitable for use in cosmetic products manufactured in or imported to China within defined concentration limits.
A. At pH below 4, HOCl begins converting to molecular chlorine (Cl₂), which is more irritating and volatile. Above pH 6, the equilibrium shifts toward the hypochlorite ion (OCl⁻), which is significantly less antimicrobially active and less able to penetrate microbial membranes. The pH 4.5–5.5 window maximises free HOCl availability — the active form — while maintaining skin-compatible acidity.
A. At cosmetic concentrations (100–500 ppm), HOCl shows broad-spectrum transient antimicrobial activity rather than selective microbiome disruption. Its effect is temporary and non-specific — unlike antibiotics, it does not select for resistance. The skin microbiome recovers rapidly after application, and commensal organisms are not permanently displaced at cosmetic use levels.
A. HOCl should not be combined with reducing agents such as high-concentration vitamin C (L-ascorbic acid), as these will rapidly neutralise the active oxidant. It is compatible with Centella Asiatica extracts, panthenol, allantoin, niacinamide (at low concentrations), and most humectants. Always confirm compatibility through stability testing when combining with actives containing thiol or aldehyde groups.
A. HOCl is an inherently reactive molecule that undergoes spontaneous decomposition over time — primarily into water and oxygen. This decomposition is accelerated by UV exposure, elevated temperatures, contamination, and pH drift. Proper packaging (opaque HDPE or glass, sealed) and cool storage conditions are essential. Stabilized commercial preparations extend shelf life through carefully controlled pH and the absence of catalytic metal ions.
A. At concentrations of 100–200 ppm and pH 4.5–5.5, HOCl is considered safe for periorbital use and has documented clinical use in blepharitis (eyelid margin inflammation) management. Products intended for direct ocular contact require additional ophthalmological safety assessment.
A. Use opaque HDPE or amber glass containers with minimal headspace to reduce UV and oxygen exposure. Pump or spray formats are preferred over open-mouth jars to limit contamination and air contact. Avoid aluminium or steel closures in direct contact with the formulation — use plastic-lined caps or inert polymer components.
Disclaimer: Information on this page has been compiled from published scientific literature and industry reference sources. Formulation recommendations are general guidelines and should be validated through appropriate stability and compatibility testing for your specific product. SBCT Labs makes no warranty, expressed or implied, regarding the suitability of information for any particular application. Users are responsible for verifying safety, efficacy, and regulatory compliance for their intended use.