PEG-40 hydrogenated castor oil on your skin: a safety profile

What is peg-40 hydrogenated castor oil?

The IUPAC name is polyethylene glycol 40 hydrogenated castor oil.

Also known as: polyethylene glycol 40 hydrogenated castor oil, PEG-40 HCO, Cremophor RH40, KMIPKYQIOVAHOP-LRHAYUFXSA-N.

IUPAC name

polyethylene glycol 40 hydrogenated castor oil

CAS number

61788-85-0

Molecular formula

(C2H4O)40-C16H32O5 (approximate)

Regulatory consensus

1 regulatory bodyhas classified PEG-40 hydrogenated castor oil.

Regulators apply different standards of evidence — animal-data weighting, exposure-pattern assumptions, epidemiological power thresholds — which is why two scientific bodies can review the same data and reach different conclusions. The disagreement is the data.

Where you encounter peg-40 hydrogenated castor oil

• creams
• lotions
• serums
• pharmaceutical formulations

Safer alternatives

Lower-risk approaches that achieve a similar outcome to PEG-40 hydrogenated castor oil:

• Decyl glucoside or other alkyl polyglucosides (APGs) — milder, plant-derived
  Trade-offs: Consumer preference for 'natural' label; many natural fragrance compounds are potent allergens (limonene, linalool, eugenol); 'natural' ≠ 'safe'; often more expensive than synthetic equivalents.
  Relative cost: 2-5× conventional
• Sodium cocoyl isethionate (SCI) — low irritation potential
  Trade-offs: Alternative surfactant; performance characteristics (foaming, emulsification, wetting) vary; biodegradability and aquatic toxicity should be assessed; formulation adjustment may be needed.
  Relative cost: 1.2-2×
• Sodium lauroyl glutamate — amino acid-based, very mild
  Trade-offs: Extremely mild (pH 5.5-6.5); biodegradable; derived from amino acids and fatty acids; premium ingredient cost; excellent consumer perception; lower foam volume than sulfate surfactants.
  Relative cost: 1.2-2×
• Cocamidopropyl betaine (amphoteric) — gentler than anionic surfactants
  Trade-offs: Removes 95-99% of dissolved contaminants including metals, PFAS, nitrates; wastes 2-4 gallons per gallon produced (improving with newer systems); removes beneficial minerals; $0.05-0.25/gallon; requires pre-treatment for longevity.
  Relative cost: 1.2-2×

Frequently asked questions