4-Hydroxybenzoic Acid
molecular structure · PubChem
AKA: 99-96-7, P-Hydroxybenzoic acid, P-Salicylic acid, 4-Carboxyphenol, Para-Hydroxybenzoic acid, P-Oxybenzoesaure
Synthetic
Preservative
Safety Concern
Acid
Not Clean
The CIR Expert Panel concluded that the following 20 parabens are safe in cosmetics in the present practices of use and concentration described in the safety assessment when the sum of the combined concentration of parabens in any given formulation does not exceed 0.8 %...4-Hydroxybenzoic Acid...
Solubility Solubility (in 100 g of solution): 99% ethanol 38.75 g (67 °C); n-butanol 19.5 g (32.5 °C)
Formula
C7H6O3
Mol. Weight
138.12
CAS #
99-96-7
Form
Liquid
State
Pellets or Large Crystals; Dry Powder
Functions
Preservative
Keeps your product from growing bacteria, mold, or yeast. Without these, that jar of cream becomes a petri dish in about a week.
Antioxidant
Brightening
Anti-Inflammatory
Prevents microbial growth
Provides scent
Traditional Use
A naturally occurring compound found in various plants that was first synthesized in the 19th century. Developed as the parent compound for parabens, a class of preservatives introduced to cosmetics in the 1920s.
EWG
3
CIR
Safe as used
Pregnancy
Yes
Restricted By
CIR Safety Findings
Not Phototoxic
ewg-3
medical-approval
all-shades-safe
Concentration Guide
8.0%
0%11%
Reg. Limit
EU regulatory limit: 8.0%. 0,4% (as acid) for single ester 0,8% (as acid) for mixtures of esters Source: EU Cosmetics Regulation (EC) 1223/2009, Annex V (Preservatives), Entry 12. Dermal absorption: 0.1%. Source: CIR Safety Assessment (CIR Seq 746).
Regulatory Agencies
Skin Types
●all-skin-types
Best For
General
Pregnancy & Breastfeeding Safe
Yes
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.
Verified Jun 2026
Data: PubChem · CosIng · EWG · CIR