murphyBoric Acid
AKA: Orthoboric acid, 10043-35-3, Boracic acid, Borofax, Boron hydroxide, Boric acid (H3BO3), Boron trihydroxide, Basilit B, Three Elephant
Synthetic
Preservative
Acid
Not Clean
OriginBoric acid belongs to the boron compound chemical family, derived from naturally occurring boron minerals or synthesized from boron sources. It is produced through the reaction of borax with sulfuric acid or by direct synthesis from boron trioxide and water.
Boric acid (H3BO3) also called hydrogen borate, boracic acid, orthoboric acid is a weak acid of boron often used as an antiseptic, insecticide, flame retardant, neutron absorber, or precursor to other chemical compounds. It has the chemical formula H3BO3 (sometimes written B(OH)3), and exists in the form of colorless crystals or a white powder that dissolves in water. When occurring as a mineral, it is called sassolite. Borate is a food contaminant deriving from paper and paperboard in contact with food. It has limited use as an antibacterial agent in caviar.
Solubility 10 to 50 mg/mL at 66 °F (NTP, 1992)
Formula
BH3O3
Mol. Weight
61.84
CAS #
10043-35-3, 11113-50-1
Form
Liquid
State
Boric acid is an odorless white solid. Melting point 171 °C. Sinks and mixes with water. (USCG, 1999)
Skin Types
●all-skin-types
Best For
General
Pregnancy & Breastfeeding Safe
No
Functions
Antimicrobial
Keeps your product from growing bacteria, mold, or yeast. Without these, that jar of cream becomes a petri dish in about a week.
Buffering
Denaturant
Fights Bacteria
The paper trail
🔬Peer-reviewed1 paper →
⚖️Regulatory1 listing →
🛡️Safety-assessed1 review →
Counts, not a verdict. A listing isn't a study. The trail, you decide.
EWG
4
CIR
Safe as used · CIR tentative re-review report (2026)
Pregnancy
No
CIR Safety Findings
Not a Sensitizer
1 study / 1 not sensitizing / plus 1 case report (CIR 215 and 912)
Mixed Eye Irritation Results
2 studies / 1 irritating / 1 mixed / reactions moderate (CIR 215 and 912)
Mixed Skin Irritation Results
7 studies / 4 irritating / 1 mixed / 2 not irritating / reactions minimal to moderate / plus 1 case report (CIR 215 and 912)
Dermal Absorption 0.23%
human in vivo (n=8) / 5% aq solution / 900 cm2 area / 24 h (CIR 912)
Concentration Guide
Leave-onNot reported
Rinse-off0.00006–0.00016%
0%50%100%
Reg. limit 5%
CIR reported use · 2025 survey
EU regulatory limit: 5.0%. (a) 5% (as boric acid) (b) 0.1% (as boric acid) (c) 3% (as boric acid). (a) Not to be used for children under 3 years of age Not to be used on peeling or irritated skin (b) Not to be swallowed Not to be used for children under 3 years of age (c) Not to be used for chi... Source: EU Cosmetics Regulation (EC) 1223/2009, Annex III (Restricted Substances), Entry 1a.
Regulatory Agencies
Verified Jun 2026
Data: PubChem · CosIng · EWG · CIR