BHA – BETA HYDROXY ACID

BHA – Beta Hydroxy Acid is the common designation for salicylic acid (2-hydroxybenzoic acid), an aromatic beta hydroxy acid and the most widely used oil-soluble chemical exfoliant in cosmetic, pharmaceutical, and dermatological applications.
BHA – Beta Hydroxy Acid is oil-soluble (lipophilic), which allows it to penetrate through sebum-filled pores and exfoliate both the skin surface and within the follicle, making it uniquely effective for oily, acne-prone, blackhead-prone, and congested skin types.
BHA – Beta Hydroxy Acid acts simultaneously as a keratolytic, comedolytic, exfoliating, anti-inflammatory, and antibacterial agent, providing multi-benefit performance that distinguishes it from water-soluble alpha hydroxy acids (AHAs).

CAS Number: 69-72-7
EC Number: 200-712-3
Molecular Formula: C7H6O3
Molecular Weight: 138.12 g/mol
IUPAC Name: 2-Hydroxybenzoic acid
COSING REF No: 37595
PubChem CID: 338

Synonyms: Salicylic Acid, BHA, Beta Hydroxy Acid, 2-Hydroxybenzoic Acid, o-Hydroxybenzoic Acid, Ortho-Hydroxybenzoic Acid, 2-Carboxyphenol, o-Carboxyphenol, Salicylate Acid, Willow Bark Extract (natural source), Sodium Salicylate (salt form), Betaine Salicylate (ester form), Capryloyl Salicylic Acid (LHA derivative), Trethocanic Acid, Beta Hydroxybutanoic Acid, NSC 180, AIDS 006789

BHA – Beta Hydroxy Acid is an odorless, colorless to white crystalline solid originally derived from the bark of the white willow tree (Salix alba) and meadowsweet plant (Filipendula ulmaria), though modern commercial production relies primarily on the Kolbe-Schmitt synthetic route.
BHA – Beta Hydroxy Acid is defined structurally as a carboxylic acid bearing a hydroxyl group on the beta carbon (the second carbon from the carboxyl group); in salicylic acid, the hydroxyl and carboxyl groups are both attached to the aromatic ring in the ortho position, conferring its unique lipophilicity and pKa of approximately 2.97.

BHA – Beta Hydroxy Acid is effective at a formulation pH of 3.0 to 4.5, which maintains the un-ionized membrane-permeable form necessary for pore penetration; above pH 4.5 the molecule ionizes and loses follicular penetration ability regardless of stated concentration.
BHA – Beta Hydroxy Acid is available as a pure crystalline powder, in alcohol-based, glycol-based, or aqueous solutions, as professional-grade chemical peel concentrations of 10–30%, and in finished cosmetic formats including cleansers, toners, serums, spot treatments, and leave-on exfoliants.

Uses of BHA – Beta Hydroxy Acid:
BHA – Beta Hydroxy Acid is used as a keratolytic and exfoliating ingredient in cosmetic and dermatological formulations including face washes, toners, serums, masks, pads, spot treatments, and leave-on exfoliants at concentrations of 0.5–2%.
BHA – Beta Hydroxy Acid is used as an OTC acne treatment to dissolve sebum and cellular debris inside blocked follicles, reducing open comedones (blackheads), closed comedones (whiteheads), and inflammatory acne lesions.

BHA – Beta Hydroxy Acid is used in pharmaceutical preparations to treat warts, psoriasis, seborrhoeic dermatitis, chronic atopic dermatitis, lichen simplex, ichthyosis, and acne vulgaris through its keratolytic softening of the outermost skin layer.
BHA – Beta Hydroxy Acid is used as a chemical peel agent in clinical and professional dermatological settings at concentrations of 10–30% to treat photoaging, hyperpigmentation, post-acne scarring, and uneven skin tone.

BHA – Beta Hydroxy Acid is used in scalp care and anti-dandruff products including shampoos, conditioners, and scalp treatments as a keratolytic agent that loosens and removes scalp buildup and flaking.
BHA – Beta Hydroxy Acid is used in foot care formulations including callus removers, corn plasters, and foot creams at higher concentrations of 10–40% to soften and remove thickened, hyperkeratotic skin.

BHA – Beta Hydroxy Acid is used in anti-aging skincare formulations to promote cellular turnover, improve skin tone and texture, reduce the appearance of fine lines and wrinkles, minimize pore appearance, and enhance penetration of other active ingredients.
BHA – Beta Hydroxy Acid is used in body care products including body washes and lotions targeting keratosis pilaris, rough elbows and knees, and body acne on the back and shoulders.

BHA – Beta Hydroxy Acid is used in the production of other pharmaceuticals including acetylsalicylic acid (aspirin), 4-aminosalicylic acid, sandulpiride, and landetimide, and as an intermediate in dye and fragrance manufacturing.
BHA – Beta Hydroxy Acid is used as a food preservative, bactericide, and antiseptic, and as a laboratory analytical reagent and chelating agent for iron(III) detection.

BHA – Beta Hydroxy Acid is used in combination with AHAs, niacinamide, retinol, and vitamin C in multi-functional formulations delivering complementary exfoliating, brightening, pore-refining, and anti-aging benefits.
BHA – Beta Hydroxy Acid is not recommended for use in products intended for children under three years of age (other than shampoos), oral products, or inhalable formulations under EU cosmetics legislation.

Benefits or Advantages of BHA – Beta Hydroxy Acid:
BHA – Beta Hydroxy Acid offers deep pore penetration due to its oil solubility, enabling exfoliation and sebum dissolution within the follicle where water-soluble acids cannot reach, providing source-level clearing of pore congestion.
BHA – Beta Hydroxy Acid provides dual-action exfoliation: working on the skin surface by removing corneocytes and within the pore by dissolving the sebum-cell plug that causes blackheads and comedones.

BHA – Beta Hydroxy Acid possesses anti-inflammatory properties that reduce redness, swelling, and irritation in acne lesions while simultaneously exfoliating, making it gentler than AHAs for inflamed or reactive skin.
BHA – Beta Hydroxy Acid regulates sebum production over time, reducing excess oil and shine and disrupting the pore-clogging cycle that leads to recurrent breakouts.

BHA – Beta Hydroxy Acid improves skin texture, tone, and clarity through consistent use by promoting keratinocyte turnover, revealing fresher skin and reducing post-acne marks and hyperpigmentation.
BHA – Beta Hydroxy Acid is effective at low concentrations of 0.5–2%, requires no rinsing as a leave-on ingredient, and is widely available in consumer products making it one of the most accessible daily exfoliants.

Features of BHA – Beta Hydroxy Acid:
BHA – Beta Hydroxy Acid is a white to off-white odorless crystalline powder or crystal that sublimes at 76°C, melts at 158–161°C, has a density of 1.443 g/cm3, and a refractive index of 1.565.
BHA – Beta Hydroxy Acid has a pKa of approximately 2.97, an XLogP3 of 2.3, and is slightly soluble in water (2.48 g/L at 25°C), freely soluble in ethanol, acetone, and ether, and soluble in benzene, chloroform, and methanol.

BHA – Beta Hydroxy Acid is lipophilic (oil-soluble), enabling it to penetrate the lipid-rich stratum corneum and dissolve sebum within the follicular infundibulum, which water-soluble acids cannot access.
BHA – Beta Hydroxy Acid is keratolytic, desmolytic, comedolytic, antibacterial, and anti-inflammatory; it works by weakening corneal desmosome bonds (desmolytic effect), inhibiting COX-1 enzymatic activity, and dissolving the sebum-keratin plug inside blocked follicles.

Chemical Properties of BHA – Beta Hydroxy Acid:
BHA – Beta Hydroxy Acid (salicylic acid) has the molecular formula C7H6O3, molecular weight 138.12 g/mol, SMILES C1=CC=C(C(=C1)C(=O)O)O, InChIKey YGSDEFSMJLZEOE-UHFFFAOYSA-N, and InChI InChI=1S/C7H6O3/c8-6-4-2-1-3-5(6)7(9)10/h1-4,8H,(H,9,10).
BHA – Beta Hydroxy Acid is an aromatic monohydroxybenzoic acid with a benzene ring bearing a carboxyl group and an ortho-hydroxyl group; its lipophilicity arises from the aromatic ring, while the carboxyl group provides acidity; the pKa of the carboxylic group is 2.97 and the phenolic group is 13.82.

BHA – Beta Hydroxy Acid modulates COX-1 enzymatic activity, decreasing formation of pro-inflammatory prostaglandins; it also competitively inhibits UDPG oxidation and the transfer of glucuronyl groups, contributing to its anti-inflammatory mechanism.
BHA – Beta Hydroxy Acid undergoes decarboxylation to phenol and carbon dioxide at 200–230°C, and upon stronger heating converts to phenyl salicylate and further to xanthone; as a conjugate base, salicylate is a chelating agent for iron(III).

Production of BHA – Beta Hydroxy Acid:
BHA – Beta Hydroxy Acid is produced industrially by the Kolbe-Schmitt reaction, in which sodium phenolate is treated with carbon dioxide at high pressure (100 atm) and high temperature (115°C) to form sodium salicylate, which is then acidified with sulfuric acid to yield salicylic acid.
BHA – Beta Hydroxy Acid can also be prepared at laboratory scale by hydrolysis of aspirin (acetylsalicylic acid) or methyl salicylate (oil of wintergreen) with a strong acid or base, and is biosynthesized in plants from the amino acid phenylalanine.

BHA – Beta Hydroxy Acid for cosmetic use must comply with EU Cosmetics Regulation specifications including limits for phenol and related impurities; pharmaceutical grades must meet USP, BP, EP, and JECFA specifications for assay (≥99.5%), melting point (158–161°C), residue on ignition (≤0.05%), and heavy metals (≤20 ppm).
BHA – Beta Hydroxy Acid is available in standard-grade and micronized particle-size grades; particle-size distribution significantly affects dissolution rate, dust generation, and processing behavior in formulation.

Material Safety Data Sheet (MSDS) of BHA – Beta Hydroxy Acid:

Handling of BHA – Beta Hydroxy Acid:
BHA – Beta Hydroxy Acid should be handled in accordance with good industrial hygiene and safety practices and in compliance with Section 7 precautions.
BHA – Beta Hydroxy Acid handling requires avoiding inhalation of dust, contact with eyes, and prolonged skin contact with concentrated material; concentrated powder must not be applied directly to skin.

SDS of BHA – Beta Hydroxy Acid:

Stability and Reactivity of BHA – Beta Hydroxy Acid:

Chemical stability:
BHA – Beta Hydroxy Acid is stable under normal temperature, dry storage, and recommended handling conditions.

Reactivity:
No hazardous reaction is expected under normal recommended handling and storage conditions.
BHA – Beta Hydroxy Acid may react with strong oxidizing agents, strong bases (forming salicylate salts with heat release), and acid-reactive metals under certain conditions.

Conditions to avoid:
Excessive heat.
Open flames and hot surfaces.
Sparks and static discharge.
Moisture and humidity.
Dust generation and accumulation.
Direct sunlight.
Contact with incompatible materials.

Incompatible materials:
Strong oxidizing agents.
Strong alkalis and bases.
Strong reducing agents under reactive conditions.
Acid-reactive metals.
Acid chlorides and reactive chemical intermediates.

Hazardous decomposition products:
Carbon monoxide (CO).
Carbon dioxide (CO2).
Phenolic compounds and phenolic fumes.
Irritating organic vapors and smoke.
Partially oxidized decomposition products.

Handling and Storage of BHA – Beta Hydroxy Acid:

Handling:
Read the label and this safety data sheet before use.
Handle BHA – Beta Hydroxy Acid in a well-ventilated area.
Avoid inhalation of dust; use local exhaust ventilation at points where dust may be generated.
Avoid contact with eyes, skin, and clothing; minimize dust formation during weighing, transfer, mixing, and charging.
Do not eat, drink, smoke, or apply cosmetics in handling areas.
Wash hands, forearms, and face thoroughly after handling.
Remove contaminated clothing before entering eating or rest areas.
Do not use concentrated raw BHA – Beta Hydroxy Acid powder directly on the skin.

Storage:
Store BHA – Beta Hydroxy Acid in the original, tightly closed, and properly labeled container.
Keep in a cool, dry, and well-ventilated area away from ignition sources and incompatible materials.
Protect from moisture, excessive heat, and direct sunlight.
Store separately from strong oxidizing agents and strong bases.
Some suppliers recommend storage below approximately 15°C for optimum quality.
Keep containers upright and prevent damage; avoid storage in humid conditions to prevent caking.
Shelf life is typically 2 to 3 years under recommended storage conditions.

First Aid Measures of BHA – Beta Hydroxy Acid:

Inhalation:
Move the affected person to fresh air; keep warm, at rest, and in a comfortable breathing position.
If coughing, throat irritation, headache, dizziness, or breathing difficulty occurs, obtain medical advice.
If breathing has stopped, trained personnel should provide artificial respiration.

Skin contact:
Remove contaminated clothing, shoes, and accessories.
Brush away excess dry powder carefully before washing.
Wash affected skin thoroughly with soap and plenty of water for at least 15 minutes.
Seek medical advice if redness, pain, burning, peeling, or persistent irritation develops.
Wash contaminated clothing before reuse.

Eye contact:
Immediately rinse cautiously with clean, lukewarm water for at least 15 to 20 minutes while holding eyelids open.
Remove contact lenses if present and easy to do; do not allow rubbing of eyes.
Continue rinsing during transport to medical care where possible.
Seek immediate medical attention because BHA – Beta Hydroxy Acid causes serious eye damage.

Ingestion:
Rinse the mouth thoroughly with water.
Do not induce vomiting unless instructed by medical personnel.
Give small amounts of water if the person is fully conscious and able to swallow.
Immediately contact a poison center or physician; keep the person under observation as symptoms may be delayed.

Firefighting Measures of BHA – Beta Hydroxy Acid:

Suitable extinguishing media:
Water spray, alcohol-resistant foam, dry chemical powder, or carbon dioxide.

Unsuitable extinguishing media:
Do not use a high-pressure water jet directly on spilled powder as it may scatter BHA – Beta Hydroxy Acid and spread contamination.

Specific hazards:
BHA – Beta Hydroxy Acid is a combustible organic solid; fine dust dispersed in air may create a combustible dust hazard, particularly in enclosed processing equipment.
Thermal decomposition and combustion may generate carbon monoxide, carbon dioxide, phenolic fumes, irritating organic vapors, and partially oxidized decomposition products.

Protective equipment for firefighters:
Wear self-contained breathing apparatus (SCBA) in positive-pressure mode and complete fire-resistant protective clothing.

Firefighting instructions:
Evacuate unnecessary personnel; approach the fire from upwind.
Cool containers exposed to heat with water spray.
Prevent contaminated firefighting water from entering drains, soil, and surface water; collect contaminated water separately where practicable.

Accidental Release Measures of BHA – Beta Hydroxy Acid:

Personal precautions:
Evacuate non-essential personnel and restrict access to the contaminated area.
Avoid generating or breathing BHA – Beta Hydroxy Acid dust; provide adequate ventilation.
Avoid contact with eyes, skin, and clothing; wear suitable protective gloves, clothing, eye protection, and respiratory protection.
Eliminate ignition sources if large quantities of fine BHA – Beta Hydroxy Acid dust have been released.

Environmental precautions:
Prevent BHA – Beta Hydroxy Acid from entering drains, sewers, soil, groundwater, and surface water.
Notify the appropriate environmental authority if significant environmental contamination occurs.

Methods for cleaning up:
Stop the release if safe to do so; cover drains and prevent further spreading.
Collect spilled BHA – Beta Hydroxy Acid using a HEPA-filtered industrial vacuum suitable for hazardous dust; avoid dry sweeping that creates airborne dust.
Alternatively, carefully sweep or shovel material into a clean, dry, and properly labeled container.
Use damp-cleaning methods for final residue removal; ventilate the area and wash exposed surfaces after collection.
Dispose of contaminated absorbents and cleaning materials according to local regulations.

Exposure Controls / Personal Protective Equipment of BHA – Beta Hydroxy Acid:

Engineering controls:
Provide adequate general or local exhaust ventilation, particularly at weighing, transfer, blending, grinding, and filling points.
Install dust collection equipment designed for the relevant dust hazard; use explosion-protected systems when industrial-scale dust concentrations may form.
Provide emergency eyewash stations and safety showers near BHA – Beta Hydroxy Acid handling areas.

Eye protection:
Wear tightly fitting chemical safety goggles; add a face shield when splashing or significant dust exposure is possible.

Hand protection:
Wear chemical-resistant protective gloves such as nitrile rubber, neoprene, or butyl rubber; select according to breakthrough time and exposure duration.
Inspect gloves before use and replace damaged or contaminated gloves immediately.

Skin and body protection:
Wear a laboratory coat, protective workwear, or chemical-resistant clothing; use closed footwear and disposable coveralls when significant dust contamination is possible.

Respiratory protection:
For dust-generating operations of BHA – Beta Hydroxy Acid, use a properly fitted particulate respirator (P2/FFP2 or equivalent for moderate dust; P3/N95 or higher for greater exposure).
Use positive-pressure supplied-air respiratory protection for emergency response or unknown concentrations.
Respirator selection and use must follow a written respiratory protection program.

Hygiene measures:
Do not eat, drink, smoke, or touch eyes or face with contaminated gloves while handling BHA – Beta Hydroxy Acid.
Wash thoroughly after handling; keep work clothing separate from personal clothing.
Clean contaminated work surfaces regularly; maintain good housekeeping to minimize dust accumulation.

Identifiers of BHA – Beta Hydroxy Acid:
Chemical name: Salicylic Acid
IUPAC Name: 2-Hydroxybenzoic Acid
CAS No.: 69-72-7
EC No.: 200-712-3
COSING REF No.: 37595
PubChem CID: 338
ChemSpider: 331
ChEBI: CHEBI:16914
ChEMBL: ChEMBL424
DrugBank: DB00936
KEGG: D00097 / C00805
UNII: O414PZ4LPZ
HMDB ID: HMDB0001895
ECHA InfoCard: 100.000.648
RTECS: VO0525000
CompTox Dashboard (EPA): DTXSID7026368
FEMA Number: 3985
JECFA Number: 958
ICSC Number: 0563
NSC Number: NSC 180
PharmGKB ID: PA451299
RXCUI: 9525
Wikidata: Q193572
InChIKey: YGSDEFSMJLZEOE-UHFFFAOYSA-N
InChI: InChI=1S/C7H6O3/c8-6-4-2-1-3-5(6)7(9)10/h1-4,8H,(H,9,10)
SMILES: C1=CC=C(C(=C1)C(=O)O)O
ATC Code: A01AD05; B01AC06; D01AE12; N02BA01; S01BC08 (WHO)
GHS Classification: Acute Tox. 4 (H302); Eye Dam. 1 (H318); Repr. 2 (H361 — where applicable)
Signal Word: Danger
Substance Form: Solid
Product Type: Aromatic beta hydroxy acid
Function: Keratolytic, comedolytic, exfoliant, anti-inflammatory, antibacterial, antiperspirant, anti-dandruff, preservative, hair-conditioning agent, chemical intermediate

Properties of BHA – Beta Hydroxy Acid:
Physical state: Solid
Appearance: White to off-white crystalline powder, crystals, or needles
Odor: Odorless or faint characteristic odor
Density: 1.443 g/cm3 (20°C)
Melting point: 158–161°C
Boiling point: 211°C (at 20 mmHg); sublimes at 76°C
Flash point: Approximately 157°C
Auto-ignition temperature: Approximately 540°C
pKa: 2.97 (carboxylic acid group, 25°C); 13.82 (phenol group, 20°C)
XLogP3: 2.3
Topological Polar Surface Area: 57.5 Ų
Hydrogen Bond Donors: 2
Hydrogen Bond Acceptors: 3
Refractive index: 1.565 (20°C)
Dipole moment: 2.65 D
Magnetic susceptibility: −72.23 × 10⁻⁶ cm3/mol
UV absorption (λmax): 210 nm, 234 nm, 303 nm (in ethanol)
Solubility in water: 1.24 g/L (0°C); 2.48 g/L (25°C); 4.14 g/L (40°C); 17.41 g/L (75°C); 77.79 g/L (100°C)
Solubility in ethanol: Freely soluble
Solubility in acetone: 39.6 g/100 g (23°C)
Solubility in methanol: 62.48 g/100 g (21°C)
Solubility in chloroform: 2.22 g/100 mL (25°C)
Solubility in benzene: 0.775 g/100 g (25°C)
Solubility in olive oil: 2.43 g/100 g (23°C)
Vapor pressure: 10.93 mPa
Std enthalpy of formation (ΔfH°298): −589.9 kJ/mol
Std enthalpy of combustion (ΔcH°298): −3.025 MJ/mol
Oil solubility: Yes (lipophilic)
Effective formulation pH range: 3.0–4.5 (un-ionized form)

Specifications of BHA – Beta Hydroxy Acid:
Chemical name: BHA – Beta Hydroxy Acid (Salicylic Acid)
Molecular formula: C7H6O3
Molecular weight: 138.12 g/mol
CAS Number: 69-72-7
Assay (USP/EP, dried basis): ≥99.5%
Assay (cosmetic/industrial): ≥99.0%
Melting point: 158–161°C
One early melting point: ≥156.0°C
Loss on drying: ≤0.5%
Residue on ignition: ≤0.05%
Phenol and related impurities: ≤0.05–0.20%
Heavy metals (as Pb): ≤20 ppm
Arsenic (As): ≤3 ppm
pH (aqueous solution): Acidic (~2.4 at saturation)
Typical cosmetic leave-on concentration: 0.5–2.0%
Typical cosmetic rinse-off hair product: up to 3.0%
Professional peel concentration: 10–30%
FDA OTC acne treatment: 0.5–2%
EU permitted maximum (leave-on): 2.0%
EU permitted maximum (rinse-off hair): 3.0%
EU restriction: Not for use in children under 3 years (except shampoos); not in oral or inhalable products
Storage conditions: Store in tightly closed containers at 15 to 25°C (some suppliers recommend below 15°C), dry, away from heat and direct sunlight; shelf life typically 2–3 years
Transport regulations: Generally not regulated as dangerous goods (solid, commercial quantities); solutions in flammable solvents may be regulated separately

Names of BHA – Beta Hydroxy Acid:
BHA – Beta Hydroxy Acid
Salicylic Acid
2-Hydroxybenzoic Acid
o-Hydroxybenzoic Acid
Ortho-Hydroxybenzoic Acid
2-Carboxyphenol
o-Carboxyphenol
Salicylate Acid
Beta Hydroxy Acid
BHA
Willow Bark Extract (natural source)
Sodium Salicylate (sodium salt form)
Betaine Salicylate (ester form)
Capryloyl Salicylic Acid / LHA (C8 derivative)
Trethocanic Acid
CAS 69-72-7