How is skin's pH affected by the use of soap (pH 9-10)?

simonasimona Member
edited February 2014 in Skin
Soap has an alkaline pH so it is expected to raise the skin's pH when used. But has this been measured, how big is the impact on the skin? 

There are people claiming that soap is bad for the skin because it is too alkaline. I understand the concern, but most of us apply toners/lotions/moisturizers with a pH closer to our acid mantle's pH. So I expect that, after washing with a soap, using a salicylic acid treatment or a simple face cream woudl help the skin. true or false? 


  • chemicalmattchemicalmatt Member, Professional Chemist
    Simona, most bar soaps are mildly alkaline, as you've noted. These do not raise the "acid mantle" of the dermis all that much.  No need for strongly acidic post-treatment.  Most standard skin-care lotions have a pH in the 6.0 - 7.0 range, and should suffice. Also, those "people claiming" this condition are not chemists. Most syndet bar soaps are much milder on the skin than the old harsh coco-alkali ones, and lots of glycerin and olive oil ("Castille")soapers are in business today as well. As always, use empirical knowledge:  billions of people have used bar soaps for over a hundred years. Have the complaints registered in the thousands? millions? I rest my case.
  • Matt,

    That is the problem with trying to formulate. If you use google and type in any ingredient, you will see a group of people warning against its use. Everyone thinks that man-made ingredients are all toxic and that anything that is 'natural' is 100% safe.

    I always use the analogy of H2O. Water is essential for life. Drink it in small amounts - less than 4 litres a day -  and you will be very healthy. But, drink even a medium volume of water - more than 20 litres - and you run the risk of serious health problems from too much water intake.

    Does anyone remember the radio contestants who died from drinking too much water within a 2 hr period? Refer to that safety history the next time someone tells you that certain ingredients are toxic when consumed in large amounts.

  • chemicalmattchemicalmatt Member, Professional Chemist

    Copy that, Mike.  Just today I read this week's issue of C&E News (17-FEB-14) and learned about the nefarious WERCS program being commanded by the likes of Walmart and Target stores. This was curated by the Environmental Defense Fund.  When will they stop with the fear mongering?

    F.Y.I., my favorite danger chemical (HEALTH:3, FLAMMABILITY:3) is a dry gin martini!

Sign In or Register to comment.