Natural Oils Affect the Human Skin Integrity and the Percutaneous Penetration of Benzoic Acid Dose-Dependently

Basic Clin Pharmacol Toxicol. 2006 Jun;98(6):575-81. doi: 10.1111/j.1742-7843.2006.pto_388.x.


Natural oils are extensively used in cosmetics and as treatment for a growing number of more or less specific ailments. Skin irritation and cases of allergy have repeatedly been described in the literature following exposure to these oils. The present study evaluated the extent to which three natural oils (eucalyptus oil, tea tree oil, peppermint oil) would affect the skin integrity and the percutaneous penetration of benzoic acid when applied topically in relevant concentrations. An experimental in vitro model using static diffusion cells mounted with human breast or abdominal skin was applied. The three natural oils decreased the skin integrity dose-dependently. Concomitant dermal exposure to low concentrations of peppermint oil reduced the percutaneous penetration of benzoic acid. The present study lends support to the notion that low concentrations of peppermint oil may act protective against percutaneous penetration of some chemicals, whereas higher concentrations may decrease the integrity of the dermal barrier.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Benzoic Acid / administration & dosage*
  • Benzoic Acid / pharmacokinetics*
  • Dose-Response Relationship, Drug
  • Eucalyptus / chemistry
  • Eucalyptus Oil
  • Female
  • Humans
  • In Vitro Techniques
  • Middle Aged
  • Monoterpenes / administration & dosage
  • Monoterpenes / chemistry
  • Monoterpenes / pharmacology
  • Oils, Volatile / administration & dosage
  • Oils, Volatile / chemistry
  • Oils, Volatile / pharmacology*
  • Plant Oils / administration & dosage
  • Plant Oils / chemistry
  • Plant Oils / pharmacology*
  • Skin / drug effects*
  • Skin Absorption / physiology*
  • Tea Tree Oil / administration & dosage
  • Tea Tree Oil / chemistry
  • Tea Tree Oil / pharmacology*
  • Time Factors
  • Tritium
  • Water / chemistry


  • Eucalyptus terpene oil
  • Monoterpenes
  • Oils, Volatile
  • Plant Oils
  • Water
  • Tritium
  • Eucalyptus Oil
  • Tea Tree Oil
  • Benzoic Acid
  • peppermint oil