The long-term use of soap does not affect the pH-maintenance mechanism of human skin

Skin Res Technol. 2015 May;21(2):144-8. doi: 10.1111/srt.12170. Epub 2014 Jul 30.


Background: The pH at the surface of healthy human skin is around 5. Cleansing the skin with soap increases the pH of the skin, which then returns to a more acidic pH within a few hours. However, the effects of skin cleansing with soap over a long time on the pH regulatory system is still unclear.

Object: We compared the pH of the skin between users of a soap-based cleanser and of a mild-acidic cleanser prior to and following the cleansing.

Method: This study had two groups of subjects, one group who had used a soap-based cleanser for more than 5 years and the other group who had used a mild-acidic cleanser for more than 5 years. The pH on the inner forearm of each subject was measured prior to and for 6 h after cleansing with a soap bar.

Result: There were no differences between the pH of the skin these two groups prior to cleansing, immediately after cleansing or in the pH recovery rate for 6 h.

Conclusion: These results suggest that long-term continuous use of a soap-based cleanser does not affect the pH-maintaining mechanism of human skin.

Keywords: cleanser; pH; skin; soap.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Detergents / chemistry*
  • Female
  • Humans
  • Hydrogen-Ion Concentration
  • Longitudinal Studies
  • Male
  • Skin / chemistry*
  • Skin / drug effects*
  • Skin Care / methods*
  • Soaps / chemistry*
  • Soaps / pharmacology*
  • Young Adult


  • Detergents
  • Soaps