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Annex III Entry 15a 11/01/2024

POTASSIUM HYDROXIDE / SODIUM HYDROXIDE

Potassium or sodium hydroxide

POTASSIUM HYDROXIDE / SODIUM HYDROXIDE is listed in Annex III and may only be used under the conditions shown in this record. Maximum concentration in this record: (a) 5% (b) 2% (General use) and 4.5% (Professional use) Entry 15d: 1,5%.

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Restricted substance— Annex III, EU Regulation 1223/2009
Entry: 15a

Reading this entry

For the two commonest alkalis in cosmetics, the limit is often a pH rather than a percentage — up to pH 11 as a general pH adjuster, 12.7 in depilatories.

  • Nail cuticle solvent 5%. Hair straightener 2% general use, 4.5% professional.
  • As a pH adjuster in depilatories, the limit is pH 12.7; for other pH-adjusting uses it is pH 11.
  • Callosity softeners are entry 15d at 1.5%.
  • The label warnings are unusually direct: 'Contains alkali', 'Avoid contact with eyes', 'Can cause blindness'.

Sodium and potassium hydroxide appear in a great many formulations purely to adjust pH, and for that use the entry does not set a percentage at all. It sets a pH: up to 11 for general pH adjustment, up to 12.7 where the product is a depilatory. The quantity used is whatever reaches that point, and the finished product's pH is what a regulator measures.

Where the alkali is doing work rather than adjusting, percentages return. A nail cuticle solvent may contain 5%. A hair straightener may contain 2% for general use or 4.5% for professional use, and the professional version must say so on the label.

The warning text is worth quoting because it is stronger than most in the annexes and it is mandatory rather than advisory: 'Contains alkali', 'Avoid contact with eyes', 'Can cause blindness', 'Keep out of reach of children'. Which of them apply depends on the category, and a product using the entry without the matching warnings is not compliant even if its concentration is.

Checked against

Chemical identity and properties

PubChem 2D chemical structure for CAS 1310-58-3
CAS 1310-58-3PubChem CID 14797

Potassium Hydroxide

Potassium hydroxide is an alkali metal hydroxide. — ChEBI

IUPAC name
potassium hydroxide
Molecular formula
HKO
Molecular weight
56.106 g/mol
Exact mass
55.96644614 Da
Topological polar surface area
1.0 Ų
Hydrogen-bond donors
1
Hydrogen-bond acceptors
1
Covalent units
2
Defined stereocentres
0

Also known as

Caustic potashPotash lyePotassium hydrateHydroxyde de potassiumPotassaPotasse caustiqueCaustic-potashKali causticum
16 more reported names
Caswell No. 693Cyantek CC 723Potassium hydroxide (K(OH))KaliumhydroxidCCRIS 6569Potassio (idrossido di)Potassium (hydroxyde de)WZH3C48M4TEPA Pesticide Chemical Code 075602INS NO.525INS-525E-525CHEBI:32035KaliumhydroxydeRefChem:6672MIRACLE WATER 3 in 1
Open full PubChem recordPubChem annotations3D structure image
External database identifiers

Evidence from additional scientific databases

NIH PubChem PUG-View
Exact identifier match14797

Attributed physical-property, hazard, environmental and use annotations.

  • Autoignition Temperature: Not flammable (USCG, 1999) Source: CAMEO Chemicals
  • First Aid: (Act quickly]); EYES: flush with water for at least 15 min.; SKIN: flush with water, then rinse with dilute vinegar (acetic acid).; INGESTION: give water and milk. Do NOT induce vomiting. Call physician at once, even when injury seems to be slight. (USCG, 1999) Source: CAMEO Chemicals
  • First Aid: EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop.; SKIN: IMMEDIATELY flood affected skin with water while removing and isolating all contaminated clothing. Gently wash all affected skin areas thoroughly with soap and water. IMMEDIATELY call a hospital or poison control center even if no symptoms (such as redness or irritation) develop. IMMEDIATELY transport the victim to a hospital for treatment after washing the affected areas.; INHALATION: IMMEDIATELY leave the contaminated area; take deep breaths of fresh air. If symptoms (such as wheezing, coughing, shortness of breath, or burning in the mouth, throat, or chest) develop, call a physician and be prepared to transport the victim to a hospital. Provide proper respiratory protection to rescuers entering an unknown atmosphere. Whene Source: CAMEO Chemicals
  • ERG2024, Guide 154 (Potassium hydroxide, solution; Potassium hydroxide, solid): General First Aid:; · Call 911 or emergency medical service.; · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination.; · Move victim to fresh air if it can be done safely.; · Administer oxygen if breathing is difficult.; · If victim is not breathing:; -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance.; -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).; -- If no pulse detected or no respiratory medical device available, provide continuous compressions. Conduct a pulse check every two minutes or monitor for any signs of spontaneous respirations.; · Remove and isolate contaminated clothing and shoes.; · For minor skin contact, avoid spreading material on unaffected skin.; · In case of contact with substance, remove immediately by flushing skin or eyes with running water for at least 20 minutes.; · For severe burns, immediate medical attention is required.; · Effects of exposure (inhalation, ingestion, Source: Emergency Response Guidebook (ERG)
  • ERG2024, Guide 154 (Potassium hydroxide, solid; Potassium hydroxide, solution): General First Aid:; · Call 911 or emergency medical service.; · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination.; · Move victim to fresh air if it can be done safely.; · Administer oxygen if breathing is difficult.; · If victim is not breathing:; -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance.; -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).; -- If no pulse detected or no respiratory medical device available, provide continuous compressions. Conduct a pulse check every two minutes or monitor for any signs of spontaneous respirations.; · Remove and isolate contaminated clothing and shoes.; · For minor skin contact, avoid spreading material on unaffected skin.; · In case of contact with substance, remove immediately by flushing skin or eyes with running water for at least 20 minutes.; · For severe burns, immediate medical attention is required.; · Effects of exposure (inhalation, ingestion, Source: Emergency Response Guidebook (ERG)
  • ERG2024, Guide 154 (Caustic potash, solution; Caustic potash, solid): General First Aid:; · Call 911 or emergency medical service.; · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination.; · Move victim to fresh air if it can be done safely.; · Administer oxygen if breathing is difficult.; · If victim is not breathing:; -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance.; -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).; -- If no pulse detected or no respiratory medical device available, provide continuous compressions. Conduct a pulse check every two minutes or monitor for any signs of spontaneous respirations.; · Remove and isolate contaminated clothing and shoes.; · For minor skin contact, avoid spreading material on unaffected skin.; · In case of contact with substance, remove immediately by flushing skin or eyes with running water for at least 20 minutes.; · For severe burns, immediate medical attention is required.; · Effects of exposure (inhalation, ingestion, Source: Emergency Response Guidebook (ERG)
  • First Aid: (General first aid procedures); Eye: Irrigate immediately - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately.; Skin: Water flush immediately - If this chemical contacts the skin, immediately flush the contaminated skin with water. If this chemical penetrates the clothing, immediately remove the clothing and flush the skin with water. Get medical attention promptly.; Breathing: Respiratory support; Swallow: Medical attention immediately - If this chemical has been swallowed, get medical attention immediately. Source: The National Institute for Occupational Safety and Health (NIOSH)
  • Signal: Danger Source: Regulation (EC) No 1272/2008 of the European Parliament and of the Council
  • GHS Hazard Statements: H302: Harmful if swallowed [Warning Acute toxicity, oral]; H314: Causes severe skin burns and eye damage [Danger Skin corrosion/irritation] Source: Regulation (EC) No 1272/2008 of the European Parliament and of the Council
  • Precautionary Statement Codes: P260, P264, P270, P280, P301+P317, P301+P330+P331, P302+P361+P354, P304+P340, P305+P354+P338, P316, P321, P330, P363, P405, and P501 (click each P-code to see the statement) Source: Regulation (EC) No 1272/2008 of the European Parliament and of the Council
  • Note: This chemical does not meet GHS hazard criteria for < 0.1% (3 of 4709) of reports. Source: European Chemicals Agency (ECHA)
  • Signal: Danger Source: European Chemicals Agency (ECHA)
  • GHS Hazard Statements: H290 (20.9%): May be corrosive to metals [Warning Corrosive to Metals]; H302 (96.1%): Harmful if swallowed [Warning Acute toxicity, oral]; H314 (99.4%): Causes severe skin burns and eye damage [Danger Skin corrosion/irritation]; H318 (24.7%): Causes serious eye damage [Danger Serious eye damage/eye irritation] Source: European Chemicals Agency (ECHA)
  • Precautionary Statement Codes: P234, P260, P264, P264+P265, P270, P280, P301+P317, P301+P330+P331, P302+P361+P354, P304+P340, P305+P354+P338, P316, P317, P321, P330, P363, P390, P405, P406, and P501 (click each P-code to see the statement) Source: European Chemicals Agency (ECHA)
  • ECHA C&L Notifications Summary: Aggregated GHS information provided per 4709 reports by companies from 79 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.; Reported as not meeting GHS hazard criteria per 3 of 4709 reports by companies.; There are 78 notifications provided by 4706 of 4709 reports by companies with hazard statement code(s).; Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website. Source: European Chemicals Agency (ECHA)
  • Signal: Danger Source: NITE-CMC
  • GHS Hazard Statements: H301: Toxic if swallowed [Danger Acute toxicity, oral]; H304: May be fatal if swallowed and enters airways [Danger Aspiration hazard]; H314: Causes severe skin burns and eye damage [Danger Skin corrosion/irritation]; H318: Causes serious eye damage [Danger Serious eye damage/eye irritation]; H370: Causes damage to organs [Danger Specific target organ toxicity, single exposure]; H372: Causes damage to organs through prolonged or repeated exposure [Danger Specific target organ toxicity, repeated exposure] Source: NITE-CMC
  • Precautionary Statement Codes: P260, P264, P264+P265, P270, P280, P301+P316, P301+P330+P331, P302+P361+P354, P304+P340, P305+P354+P338, P308+P316, P316, P317, P319, P321, P330, P331, P363, P405, and P501 (click each P-code to see the statement) Source: NITE-CMC
  • GHS Hazard Statements: H301: Toxic if swallowed [Danger Acute toxicity, oral]; H304: May be fatal if swallowed and enters airways [Danger Aspiration hazard]; H314: Causes severe skin burns and eye damage [Danger Skin corrosion/irritation]; H318: Causes serious eye damage [Danger Serious eye damage/eye irritation]; H370: Causes damage to organs [Danger Specific target organ toxicity, single exposure] Source: NITE-CMC
  • Cosmetic Ingredient Review Conclusion: The CIR Expert Panel concluded that ... Potassium Hydroxide is safe in hair straighteners and depilatories under conditions of recommended use; users should minimize skin contact. These ingredients are safe for all other present practices of use and concentration described in this safety assessment when formulated to be nonirritating. Source: Cosmetic Ingredient Review (CIR)
  • Cosmetic Ingredient Review Finding(s): Safe for use in cosmetics, with qualifications Source: Cosmetic Ingredient Review (CIR)
  • Toxicity Summary: IDENTIFICATION AND USE: Potassium hydroxide (KOH) is commercialized as a solid or as solutions with varying concentrations. It is used in soap manufacture; drain and pipeline cleaners; bleaching agents; manufacture of potassium carbonate and tetrapotassium pyrophosphate, an electrolyte in alkaline storage batteries and some fuel cells, absorbent for carbon dioxide and hydrogen sulfide; dyestuffs; liquid fertilizers; food additive; herbicides; electroplating; mercerizing; and paint removers. HUMAN EXPOSURE AND TOXICITY: Potassium hydroxide causes direct local effects on the skin, eyes and gastrointestinal tract after direct exposure. If KOH aerosols/mists occur, they will cause direct local effects on respiratory tract. Solutions with concentrations higher than 2% are corrosive, while concentrations of about 0.5 to about 2.0 % are irritating. The irritant effects are reported as coughing, wheezing, conjunctivitis, tearing, and irritation. Children may be accidentally exposed to commercial cleaning products. In a retrospective clinical study with 168 children after alkaline substance ingestion, 9 children (5.3%) developed gastric outlet obstruction. The fatal complications from an al Source: Hazardous Substances Data Bank (HSDB)
  • Consumer Uses: Solvent; Anti-adhesive/cohesive; Anti-freeze agent; Other; Lubricating agent; Processing aids not otherwise specified; Surfactant (surface active agent); Chemical reaction regulator; Fuel agents; pH regulating agent; Cleaning agent; Ion exchange agent; Not Known or Reasonably Ascertainable; Corrosion inhibitor; Soil amendments (fertilizers); Etching agent; Processing aids, specific to petroleum production; Intermediate Source: EPA Chemical Data Reporting (CDR)
  • Industry Uses: Ion exchange agent; Catalyst; Corrosion inhibitor; Not Known or Reasonably Ascertainable; Soil amendments (fertilizers); Cleaning agent; Absorbent; Oxidizing agent; Surface modifier; Processing aids, specific to petroleum production; Intermediate; Chelating agent; Etching agent; Adhesion/cohesion promoter; Freeze-thaw additive; Lubricating agent; Other; Flavoring and nutrient; Anti-adhesive/cohesive; Anti-freeze agent; Conductive agent; Fuel agents; pH regulating agent; Plating agent; Abrasives; Chemical reaction regulator; Semiconductor and photovoltaic agent; Surfactant (surface active agent); Processing aids not otherwise specified Source: EPA Chemical Data Reporting (CDR)
  • Cosmetic Ingredient Review Link: CIR ingredient: Potassium Hydroxide Source: Cosmetic Ingredient Review (CIR)
  • Sources/Uses: Used to make liquid soaps; it is also used in paint, varnish removers, and drain cleaners; it is used in electroplating, photoengraving, and lithography. [ACGIH] Used as a wet etchant in semiconductor manufacturing at standard concentrations of 50% or 10%; [CSH, p. 46] Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
  • Industrial Processes with risk of exposure: Acid and Alkali Cleaning of Metals [Category: Clean]; Electroplating [Category: Plate]; Semiconductor Manufacturing [Category: Industry]; Battery Manufacturing [Category: Industry]; Photographic Processing [Category: Other] Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
  • Activities with risk of exposure: Lithography printing [Category: Hobbies] Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
  • Uses: For potassium hydroxide (USEPA/OPP Pesticide Code: 075602) there are 0 labels match. /SRP: Not registered for current use in the U.S., but approved pesticide uses may change periodically and so federal, state and local authorities must be consulted for currently approved uses./ Source: Hazardous Substances Data Bank (HSDB)
  • Uses: The active ingredient is no longer contained in any registered pesticide products ... "cancelled." Source: Hazardous Substances Data Bank (HSDB)
  • Uses: Manufacturing liquid soap; mordant for wood; absorbing CO2; mercerizing cotton; print and varnish removers; electroplating, photoengraving and lithography; printing inks; in analytical chemistry for alkalimetric titrations; in organic synthesis. Pharmaceutic aid (alkalizer). Source: Hazardous Substances Data Bank (HSDB)
  • Uses: Soap manufacture, bleaching, manufacture of potassium carbonate and tetrapotassium pyrophosphate, electrolyte in alkaline storage batteries and some fuel cells, absorbent for carbon dioxide and hydrogen sulfide, dyestuffs, liquid fertilizers, food additive, herbicides, electroplating, mercerizing, paint removers, reagent. Source: Hazardous Substances Data Bank (HSDB)
  • Uses: For more Uses (Complete) data for POTASSIUM HYDROXIDE (10 total), please visit the HSDB record page. Source: Hazardous Substances Data Bank (HSDB)

Mapped by: Existing checksum-valid CAS to unique PubChem CID match. Retrieved: 2026-08-31. Open source record

Scientific classifications and hazard annotations provide context and do not replace the market-specific regulatory decision shown above.

Additional source coverage and match status
SourceResultChecked
NIH PubChem PUG-ViewExact match2026-08-31

A recorded no-match is useful evidence that the source was checked; it is not a claim that the substance does not exist elsewhere.

Retrieved from NIH PubChem on 2026-08-31 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

PubChem 2D chemical structure for CAS 1310-73-2
CAS 1310-73-2PubChem CID 14798

Sodium Hydroxide

Sodium hydroxide is an alkali metal hydroxide. — ChEBI

IUPAC name
sodium hydroxide
Molecular formula
HNaO
Molecular weight
39.997 g/mol
Exact mass
39.99250893 Da
Topological polar surface area
1.0 Ų
Hydrogen-bond donors
1
Hydrogen-bond acceptors
1
Covalent units
2
Defined stereocentres
0

Also known as

Caustic sodaSodium hydrateAetznatronSoda lyeWhite causticSoda, causticNatriumhydroxidRohrputz
16 more reported names
PlungCollo-GrillreinCollo-TapettaFuers RohrRohrreiniger RofixHydroxyde de sodiumSodium hydroxide (Na(OH))NatriumhydroxydeSoda, hydrateSodium hydroxide dimerNatrium causticumSoda, kaustischeLewis-red devil lyeSodio(idrossido di)Sodium hydroxide (Na2(OH)2)Stamperprep
Open full PubChem recordPubChem annotations3D structure image
External database identifiers

Evidence from additional scientific databases

NIH PubChem PUG-View
Exact identifier match14798

Attributed physical-property, hazard, environmental and use annotations.

  • Autoignition Temperature: Not flammable (USCG, 1999) Source: CAMEO Chemicals
  • First Aid: (Act quickly); EYES: flush with water at once for at least 15 min.; SKIN: flush with water, then rinse with dilute vinegar (acetic acid).; INGESTION: give water and milk. Do NOT induce vomiting. Call physician at once, even when injury seems to be slight. (USCG, 1999) Source: CAMEO Chemicals
  • First Aid: Excerpt from NIOSH Pocket Guide for Sodium hydroxide:; Eye: IRRIGATE IMMEDIATELY - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately.; Skin: WATER FLUSH IMMEDIATELY - If this chemical contacts the skin, immediately flush the contaminated skin with water. If this chemical penetrates the clothing, immediately remove the clothing and flush the skin with water. Get medical attention promptly.; Breathing: RESPIRATORY SUPPORT - If a person breathes large amounts of this chemical, move the exposed person to fresh air at once. If breathing has stopped, perform artificial respiration. Keep the affected person warm and at rest. Get medical attention as soon as possible.; Swallow: MEDICAL ATTENTION IMMEDIATELY - If this chemical has been swallowed, get medical attention immediately. (NIOSH, 2024) Source: CAMEO Chemicals
  • ERG2024, Guide 154 (Sodium hydroxide, solution; Sodium hydroxide, solid): General First Aid:; · Call 911 or emergency medical service.; · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination.; · Move victim to fresh air if it can be done safely.; · Administer oxygen if breathing is difficult.; · If victim is not breathing:; -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance.; -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).; -- If no pulse detected or no respiratory medical device available, provide continuous compressions. Conduct a pulse check every two minutes or monitor for any signs of spontaneous respirations.; · Remove and isolate contaminated clothing and shoes.; · For minor skin contact, avoid spreading material on unaffected skin.; · In case of contact with substance, remove immediately by flushing skin or eyes with running water for at least 20 minutes.; · For severe burns, immediate medical attention is required.; · Effects of exposure (inhalation, ingestion, Source: Emergency Response Guidebook (ERG)
  • ERG2024, Guide 154 (Caustic soda, solid; Caustic soda, solution): General First Aid:; · Call 911 or emergency medical service.; · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination.; · Move victim to fresh air if it can be done safely.; · Administer oxygen if breathing is difficult.; · If victim is not breathing:; -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance.; -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).; -- If no pulse detected or no respiratory medical device available, provide continuous compressions. Conduct a pulse check every two minutes or monitor for any signs of spontaneous respirations.; · Remove and isolate contaminated clothing and shoes.; · For minor skin contact, avoid spreading material on unaffected skin.; · In case of contact with substance, remove immediately by flushing skin or eyes with running water for at least 20 minutes.; · For severe burns, immediate medical attention is required.; · Effects of exposure (inhalation, ingestion, Source: Emergency Response Guidebook (ERG)
  • First Aid: (General first aid procedures); Eye: Irrigate immediately - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately.; Skin: Water flush immediately - If this chemical contacts the skin, immediately flush the contaminated skin with water. If this chemical penetrates the clothing, immediately remove the clothing and flush the skin with water. Get medical attention promptly.; Breathing: Respiratory support; Swallow: Medical attention immediately - If this chemical has been swallowed, get medical attention immediately. Source: The National Institute for Occupational Safety and Health (NIOSH)
  • Signal: Danger Source: Regulation (EC) No 1272/2008 of the European Parliament and of the Council
  • GHS Hazard Statements: H314: Causes severe skin burns and eye damage [Danger Skin corrosion/irritation] Source: Regulation (EC) No 1272/2008 of the European Parliament and of the Council
  • Precautionary Statement Codes: P260, P264, P280, P301+P330+P331, P302+P361+P354, P304+P340, P305+P354+P338, P316, P321, P363, P405, and P501 (click each P-code to see the statement) Source: Regulation (EC) No 1272/2008 of the European Parliament and of the Council
  • Note: This chemical does not meet GHS hazard criteria for < 0.1% (4 of 6949) of reports. Source: European Chemicals Agency (ECHA)
  • Signal: Danger Source: European Chemicals Agency (ECHA)
  • GHS Hazard Statements: H290 (47.5%): May be corrosive to metals [Warning Corrosive to Metals]; H314 (> 99.9%): Causes severe skin burns and eye damage [Danger Skin corrosion/irritation]; H315 (36.5%): Causes skin irritation [Warning Skin corrosion/irritation]; H318 (44.1%): Causes serious eye damage [Danger Serious eye damage/eye irritation]; H319 (36.6%): Causes serious eye irritation [Warning Serious eye damage/eye irritation] Source: European Chemicals Agency (ECHA)
  • Precautionary Statement Codes: P234, P260, P264, P264+P265, P280, P301+P330+P331, P302+P352, P302+P361+P354, P304+P340, P305+P351+P338, P305+P354+P338, P316, P317, P321, P332+P317, P337+P317, P362+P364, P363, P390, P405, P406, and P501 (click each P-code to see the statement) Source: European Chemicals Agency (ECHA)
  • ECHA C&L Notifications Summary: Aggregated GHS information provided per 6949 reports by companies from 80 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.; Reported as not meeting GHS hazard criteria per 4 of 6949 reports by companies.; There are 79 notifications provided by 6945 of 6949 reports by companies with hazard statement code(s).; Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website. Source: European Chemicals Agency (ECHA)
  • GHS Hazard Statements: H290 (100%): May be corrosive to metals [Warning Corrosive to Metals]; H314 (100%): Causes severe skin burns and eye damage [Danger Skin corrosion/irritation]; H318 (100%): Causes serious eye damage [Danger Serious eye damage/eye irritation] Source: European Chemicals Agency (ECHA)
  • Precautionary Statement Codes: P234, P260, P264, P264+P265, P280, P301+P330+P331, P302+P361+P354, P304+P340, P305+P354+P338, P316, P317, P321, P363, P390, P405, P406, and P501 (click each P-code to see the statement) Source: European Chemicals Agency (ECHA)
  • ECHA C&L Notifications Summary: Aggregated GHS information provided per 2 reports by companies from 1 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.; Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website. Source: European Chemicals Agency (ECHA)
  • Signal: Danger Source: NITE-CMC
  • NFPA Health Rating: 3 - Materials that, under emergency conditions, can cause serious or permanent injury. Source: Hazardous Substances Data Bank (HSDB)
  • NFPA Fire Rating: 0 - Materials that will not burn under typical fire conditions, including intrinsically noncombustible materials such as concrete, stone, and sand. Source: Hazardous Substances Data Bank (HSDB)
  • NFPA Instability Rating: 1 - Materials that in themselves are normally stable but that can become unstable at elevated temperatures and pressures. Source: Hazardous Substances Data Bank (HSDB)
  • Cosmetic Ingredient Review Conclusion: The CIR Expert Panel concluded that ... Sodium Hydroxide is safe in hair straighteners and depilatories under conditions of recommended use; users should minimize skin contact. These ingredients are safe for all other present practices of use and concentration described in this safety assessment when formulated to be nonirritating. Source: Cosmetic Ingredient Review (CIR)
  • Cosmetic Ingredient Review Finding(s): Safe for use in cosmetics, with qualifications Source: Cosmetic Ingredient Review (CIR)
  • Environmental Fate: AQUATIC FATE: In the case of a solid, anhydrous sodium hydroxide spill on soil, ground water pollution will occur if precipitation occurs prior to clean up. Precipitation will dissolve some of the solid (with much heat given off) and create an aqueous solution of sodium hydroxide, which then would be able to infiltrate the soil. However, prediction of the concentration and properties of the solution produced would be difficult. Source: Hazardous Substances Data Bank (HSDB)
  • Consumer Uses: Adhesion/cohesion promoter; Etching agent; Flocculating agent; Intermediate; Processing aids, specific to petroleum production; Oxidizing agent; Laboratory chemicals; Dye; Cleaning agent; Plasticizer; Stabilizing agent; Soil amendments (fertilizers); Catalyst; Ion exchange agent; Not Known or Reasonably Ascertainable; Processing aids not otherwise specified; Surfactant (surface active agent); Chemical reaction regulator; Fuel agents; pH regulating agent; Bleaching agent; Solvent; Dispersing agent; Anti-freeze agent; Anti-adhesive/cohesive; Other; Lubricating agent Source: EPA Chemical Data Reporting (CDR)
  • Industry Uses: Soil amendments (fertilizers); Ion exchange agent; Catalyst; Diluent; Not Known or Reasonably Ascertainable; Thickening agent; Corrosion inhibitor; Stabilizing agent; Reducing agent; Cleaning agent; Dye; Softener and conditioner; Adsorbent; Defoamer; Intermediate; Anti-scaling agent; Processing aids, specific to petroleum production; Adhesion/cohesion promoter; Etching agent; Flocculating agent; Chelating agent; Leaching agent; Lubricating agent; Other; Sizing agent; CBI; Swelling agent; Anti-freeze agent; Anti-adhesive/cohesive; Solvent; Fuel agents; pH regulating agent; Antioxidant; Bleaching agent; Chemical reaction regulator; Plating agent; Processing aids, not otherwise listed; Processing aids not otherwise specified Source: EPA Chemical Data Reporting (CDR)
  • Cosmetic Ingredient Review Link: CIR ingredient: Sodium Hydroxide Source: Cosmetic Ingredient Review (CIR)
  • Sources/Uses: Used to neutralize acids, produce sodium salts, hydrolyze fats to make soaps, and precipitate metals; large amounts are used in petroleum refining, rayon production, and rubber reclaiming; [Merck Index # 8627] Also used in metal cleaning, electroplating, processing cotton fabrics, and bleaching; [ATSDR Medical Management] Used in photography (developing bath); [www.ci.tucson.az.us/arthazards/medium.html] In semiconductor manufacturing, sodium hydroxide is used to develop the pattern in the photoresists and also as a wet echant. [CHS, p. 44-5] Caustic soda is used in hide preparation for leather production; [PMID 21938525] Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
  • Industrial Processes with risk of exposure: Acid and Alkali Cleaning of Metals [Category: Clean]; Electroplating [Category: Plate]; Petroleum Production and Refining [Category: Industry]; Semiconductor Manufacturing [Category: Industry]; Smelting Copper or Lead [Category: Industry]; Textiles (Fiber & Fabric Manufacturing) [Category: Industry]; Leather Tanning and Processing [Category: Industry]; Photographic Processing [Category: Other]; Textiles (Printing, Dyeing, or Finishing) [Category: Industry]; Metal Extraction and Refining [Category: Industry] Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
  • Activities with risk of exposure: Textile arts [Category: Hobbies]; Applying metallic patinas [Category: Hobbies] Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
  • Uses: Both oil base and water base fracturing fluids are being used in the fracturing industry. Water base, which includes alcohol-water mixtures and low strength acids, make up the majority of treating fluids. The common chemicals added to these fluids are polymers for viscosity development, crosslinkers for viscosity enhancement, pH control chemicals, gel breakers for polymer degradation following the treatment, surfactants, clay stabilizers, alcohol, bactericides, fluid loss additives and friction reducer. /Hydraulic fracturing/ Source: Hazardous Substances Data Bank (HSDB)
  • Uses: Hydraulic fracturing uses a specially blended liquid which is pumped into a well under extreme pressure causing cracks in rock formations underground. These cracks in the rock then allow oil and natural gas to flow, increasing resource production. ... Chemical Name: Sodium hydroxide; Chemical Purpose: Adjusts the pH of fluid to maintain the effectiveness of other components, such as crosslinkers; Product Function: pH Adjusting agent. Source: Hazardous Substances Data Bank (HSDB)
  • Uses: For sodium hydroxide (USEPA/OPP Pesticide Code: 075603) ACTIVE products with label matches. /SRP: Registered for use in the U.S. but approved pesticide uses may change periodically and so federal, state and local authorities must be consulted for currently approved uses./ Source: Hazardous Substances Data Bank (HSDB)
  • Uses: In inorganic chemistry, sodium hydroxide is used in the manufacture of sodium salts, for alkaline ore digestion, and for pH regulation. Source: Hazardous Substances Data Bank (HSDB)
  • Uses: For more Uses (Complete) data for SODIUM HYDROXIDE (16 total), please visit the HSDB record page. Source: Hazardous Substances Data Bank (HSDB)

Mapped by: Existing checksum-valid CAS to unique PubChem CID match. Retrieved: 2026-08-31. Open source record

Scientific classifications and hazard annotations provide context and do not replace the market-specific regulatory decision shown above.

Additional source coverage and match status
SourceResultChecked
NIH PubChem PUG-ViewExact match2026-08-31

A recorded no-match is useful evidence that the source was checked; it is not a claim that the substance does not exist elsewhere.

Retrieved from NIH PubChem on 2026-09-02 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

Record details

Maximum concentration

(a) 5% (b) 2% (General use) and 4.5% (Professional use) Entry 15d: 1,5%

Product type

Nail cuticle solvent Hair straightener PH adjuster for depilatories Other uses as pH adjuster Callosity softener/remover (entry 15d)

Other restrictions

(b)
1. General use
2. Professional use
(c) up to pH 12.7
(d) up to pH 11

15 d Contains alcakali, Avoid contact with eyes
Keep out of reach of chindren ans Read directions for use carefully

Warnings

(a) Contains alkali
Avoid contact with eyes
Can cause blindness
Keep out of reach of children
(b) 1. Contains alkali
Avoid contact with eyes
Can cause blindness
Keep out of reach of children
2. For professional use only
Avoid contact with eyes
Can cause blindness
(c) Keep out of reach of children
Avoid contact with eyes

INCI glossary name

POTASSIUM HYDROXIDE / SODIUM HYDROXIDE

Chemical name

Potassium or sodium hydroxide

Regulatory information

Regulation

(EU) 2016/622

See every entry this act set

Identified ingredients

Key data

CAS
1310-58-3 / 1310-73-2
EC
215-181-3 / 215-185-5
Annex
III
Entry number
15a

Inventory links for POTASSIUM HYDROXIDE / SODIUM HYDROXIDE

Direct matches are limited for this record, so nearby entries from Annex III are shown as well.

Annex III 14
Nearby record in the same annex

HYDROQUINONE

CAS: 123-31-9
EC: 204-617-8
Annex III 11
Nearby record in the same annex

DICHLOROPHEN

CAS: 97-23-4
EC: 202-567-1
Annex III 16
Nearby record in the same annex

1-NAPHTHOL

CAS: 90-15-3
EC: 201-969-4
Annex III 16
Nearby record in the same annex

1-Naphthol

CAS: 90-15-3
EC: 201-969-4
Annex III 17
Nearby record in the same annex

SODIUM NITRITE

CAS: 7632-00-0
EC: 231-555-9

What Annex III means for POTASSIUM HYDROXIDE / SODIUM HYDROXIDE

POTASSIUM HYDROXIDE / SODIUM HYDROXIDE is a restricted substance under Annex III of EU Cosmetics Regulation 1223/2009. Its use in cosmetics is only permitted under the specific conditions set out in the entry above, including applicable concentration limits, product type restrictions and required warning statements.

When including this substance in a formulation, all conditions — maximum concentration, product scope and warning labels — must be met simultaneously. Compliance with one condition does not override the others.

This record is linked to 2 CosIng inventory ingredients for name and identifier cross-reference. The page also surfaces 11 related annex records with overlapping identifiers, annex logic or naming patterns.

Compliance checklist

  • Ensure formulation concentration does not exceed: (a) 5% (b) 2% (General use) and 4.5% (Professional use) Entry 15d: 1,5%
  • Confirm product type compatibility: (a) Nail cuticle solvent (b) Hair straightener (c) pH adjuster for depilatories (d) Other uses as pH adjuster Callosity softener/remover (entry 15d)
  • Include required warning statement on product label.
  • Document conditions of use in the Product Information File (PIF).

Frequently asked questions

POTASSIUM HYDROXIDE / SODIUM HYDROXIDE is listed in Annex III of EU Regulation 1223/2009 as a restricted substance. It may only be used under the conditions specified in the entry, including any maximum concentration, product type limitation and required warning statements shown above.

CAS 1310-58-3 / 1310-73-2 is the unique numerical identifier assigned to POTASSIUM HYDROXIDE / SODIUM HYDROXIDE by the Chemical Abstracts Service. In cosmetic compliance work, the CAS number is used to cross-reference the substance across regulatory databases, raw material specifications and safety assessment reports. Multiple EU annex entries may share the same CAS number if the same substance appears under different conditions or in different annexes.

The maximum concentration of (a) 5% (b) 2% (General use) and 4.5% (Professional use) Entry 15d: 1,5% applies to the concentration of the substance in the ready-to-use cosmetic product. When the substance is supplied as part of a blend or mixture, the calculation must account for the contribution of all sources in the formulation. The combined concentration must not exceed the stated limit.

Use the INCI Checker tool on this site to paste your full ingredient list (INCI) and scan it against all Annex II–VI entries. The tool highlights any ingredients that match restricted, prohibited or allergen-flagged records. This is useful for rapid compliance screening of finished product formulas or raw material declarations.
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Source note for Annex III record POTASSIUM HYDROXIDE / SODIUM HYDROXIDE

This page summarizes one Annex III record for POTASSIUM HYDROXIDE / SODIUM HYDROXIDE from public European Commission cosmetic materials and adds linked inventory or identifier matches when available.

Use this record page to review Annex III conditions for POTASSIUM HYDROXIDE / SODIUM HYDROXIDE, but confirm any final regulatory decision against the current official annex wording and source files.

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