Potassium Sulfite
molecular structure · PubChem
AKA: 10117-38-1, Dipotassium sulfite, Potassium sulphite, Sulfurous acid, Dipotassium salt, Potassium sulfite (K2SO3), Potassium salt, HSDB 5052
Synthetic
Antioxidant
Preservative
Medicated Active
Not Clean
Potassium sulphite
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
Liquid
State
Liquid
Functions
Antioxidant
Fights free radicals — the unstable molecules from UV, pollution, and stress that break down collagen and cause premature aging.
Hair Waving Or Straightening
Preservative
Keeps your product from growing bacteria, mold, or yeast. Without these, that jar of cream becomes a petri dish in about a week.
Reducing
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.
EWG
4
CIR
Reviewed by CIR
Pregnancy
Caution
CIR Safety Findings
Not an Irritant
all-shades-safe
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
Skin Types
●all-skin-types
Best For
General
Pregnancy & Breastfeeding Safe
Caution
The paper trail
🔬Peer-reviewed1 paper →
⚖️Regulatory1 listing →
🛡️Safety-assessed2 reviews →
Counts, not a verdict. A listing isn't a study. The trail, you decide.
Verified Jun 2026
Data: PubChem · CosIng · EWG · CIR