Potassium Sulfite
AKA “Dipotassium sulfite, Potassium sulphite, Sulfurous acid, dipotassium salt, Potassium sulfite (K2SO3), UNII-015KZC652E, potassium salt”
Synthetic
vote to see if the hive agrees
Ingredient Facts
Potassium sulfite
AKA: Dipotassium sulfite, Potassium sulphite, Sulfurous acid, Dipotassium salt, Potassium sulfite (K2SO3), UNII-015KZC652E, Potassium salt
Synthetic · Antioxidant | Hair Waving Or Straightening | Preservative | Reducing · EWG: 4
Plant-Derived
Antioxidant
Preservative
Medicated Active
Synthetic
Clean
A gentle preservative that keeps products fresh while helping to maintain smooth, straight hair. It also protects the formula from oxidation, ensuring consistent results over time.
Solubility White crystals or crystalline powder; sol in about 3.5 parts water; decomposed by diluted acids with evolution of sulfur dioxide; pH about 8 /dihydrate/
Formula
K2O3S
Mol. Weight
158.26
CAS #
10117-38-1, 23873-77-0
Form
Powder
Plant-Derived
Synthetic. Potassium sulfite is a salt compound synthesized from the chemical family of inorganic sulfites containing potassium. It is produced by reacting sulfur dioxide with potassium hydroxide or potassium carbonate in aqueous solution.
Function
Antioxidant | Hair Waving Or Straightening | Preservative | Reducing
Benefits
Antioxidant Protection
Neutralizes Free Radicals
Traditional Use
A salt preservative developed in the 19th century for food and cosmetic use. Functions as an antioxidant and antimicrobial agent to prevent product degradation and microbial growth.
Skin Types
all-skin-types
Best For
Target
General
Melanin-Rich Skin
Suitable
Pregnancy Safe
Caution
EWG Score4
CIR Safety Findings
all-shades-safe, Not an Irritant
Concentration Guide
0.2%
0%0%
Reg. Limit
EU regulatory limit: 0.2%. SO2) Source: EU Cosmetics Regulation (EC) 1223/2009, Annex V (Preservatives), Entry 9.
Regulatory Agencies
Verified Feb 2026
Data: PubChem · CosIng · EWG · CIR