Isopropyl alcohol (IPA) vs Denatured alcohol (ethanol)

Both isopropyl alcohol and denatured alcohol (ethanol) are commonly used in personal care products, but they have different chemical properties, effects on the skin, and regulatory implications. Here's a breakdown of the key differences, especially in the context of skin products:

1. Chemical Composition

• Isopropyl Alcohol (IPA):

  • Also known as isopropanol or rubbing alcohol.

  • Chemical formula: C₃H₈O

  • Typically sold as 70% or 99% concentration.

• Denatured Alcohol (Ethanol):

  • Ethanol (C₂H₅OH) that has been made unfit for consumption by adding denaturants like methanol, acetone, or other chemicals.

  • Used to avoid excise taxes placed on potable alcohol.

2. Skin Effects

• Isopropyl Alcohol:

  • More drying than ethanol.

  • Can be irritating to sensitive skin, especially at high concentrations.

  • Antibacterial and antiseptic properties.

  • Commonly found in hand sanitizers and cleaning products.

• Denatured Alcohol (Ethanol):

  • Also drying, but slightly gentler than isopropyl alcohol when used in lower concentrations.

  • Used in perfumes, astringents, and quick-drying cosmetics.

  • The effect on skin depends on the denaturants used—some can be more irritating than the ethanol itself.

3. Regulatory & Safety Concerns

• Isopropyl Alcohol:

  • Regulated for topical use.

  • Not safe for ingestion or internal use.

• Denatured Alcohol:

  • Also not safe for ingestion.

  • Denaturants vary by country, which can affect safety and acceptability for skin use.

  • In cosmetic formulations, it's usually labeled as Alcohol Denat.

4. Usage in Skin Products

• Isopropyl Alcohol:

  • Better for disinfecting tools or cleaning surfaces.

  • Sometimes used in small amounts in acne products or spot treatments.

  • Not ideal for leave-on skin products due to harshness.

• Denatured Alcohol:

  • Often used in perfumes, sprays, and toners for its quick-drying and solvent properties.

  • Can help active ingredients penetrate but may disrupt the skin barrier with long-term use.

Conclusion / Recommendation

For skin applications:

• Use isopropyl alcohol for surface cleaning, hand sanitizers, or bug bite sticks (in small amounts).

• Use ethanol (denatured alcohol) for perfumes or sprays—but check what it’s denatured with to avoid skin irritants.

• Neither are recommended for leave-on moisturizers or facial care products if used in high concentrations, especially for sensitive or dry skin.