Sodium Bisulfite
molecular structure · PubChem
AKA: 7631-90-5, Sodium hydrogen sulfite, Sodium hydrogensulfite, Sodium bisulphite, Monosodium sulfite, Sulfurous acid, Monosodium salt, Sodium sulhydrate, Uantax SBS, Hydrogen sodium sulfite
Synthetic
Antioxidant
Preservative
Medicated Active
Not Clean
Sodium hydrogensulfite is an inorganic sodium salt having hydrogensulfite as the counterion. It has a role as a mutagen, an allergen, a reducing agent, a food antioxidant and a food colour retention agent. It is an inorganic sodium salt and a sulfite salt. It contains a hydrogensulfite.
Solubility 29 % (NIOSH, 2024)
Formula
HNaO3S
Mol. Weight
104.06
CAS #
7631-90-5
Form
Powder
State
Sodium bisulfite appears as white crystals or crystalline powder. Slight sulfurous odor. Specific gravity 1.48. Strong irritant to skin and tissue.
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
Used since the 19th century as a preservative and antioxidant in food and cosmetics. Employed in skincare formulations to prevent oxidation of sensitive ingredients and extend product shelf life.
EWG
5
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-assessed3 reviews →
Counts, not a verdict. A listing isn't a study. The trail, you decide.
Verified Jun 2026
Data: PubChem · CosIng · EWG · CIR