Trends & research

Skin pH: It needs to be mildly acidic

When buying new skincare products, it is important to make sure the cream, lotion, etc. has the right hydrogen ion concentration. Sounds complicated? Never heard of it before? You definitely have, because we’re actually talking about pH.

We always emphasize that skincare doesn't have to be complicated and that it should be simple and fun. If we now write about the pH value of the skin, we could, of course, delve deeper into the subject matter, referring to hydrogen ion concentrations and substances that either absorb or release hydrogen ions. Instead, we'll try to keep it simple – without neglecting the importance of keeping an eye on the skin’s pH. 

What’s behind the concept of pH? 

pH is the abbreviation for “pondus Hydrogenii” or “potentia Hydrogenii”, which essentially means “power or potential of hydrogen”. The pH value is used to determine whether a liquid solution is acidic or alkaline. The scale ranges from 0 (acidic) to 14 (alkaline/basic). Pure water has a neutral pH value of 7. Skin has an average pH of 5.5, i.e. mildly acidic.

The scale of pH values ranges from 0 to 14, from acidic to alkaline, in other words from acid to lye. Here are some examples of different pH values: 

  • 0: sulfuric acid
  • 1.5 – 2: stomach acid
  • 2 – 3: lemon
  • 4.8 – 5.5: the average pH of the skin
  • 5.5 – 6.5: baby skin in the first weeks of life
  • 6.6 – 6.8: fresh milk
  • 7: water – the golden mean is referred to as neutral
  • 7.37–7.45: blood of a healthy person
  • 8: seawater
  • 9: good old soap
  • 14: caustic soda

Why does skin even have a pH value? 

As described above, the pH value serves as an index for liquid solutions. Skin by its very nature does not fall into this category, yet there is a pH value for it. This is made possible by a hydrolipidic film located directly on the skin's surface. 

In addition to water, this hydrolipidic film contains various degradation products of microorganisms and bodily substances and has a mildly acidic pH. It forms our protective acid mantle, which is intended to keep our skin – and therefore us as human beings – healthy. We are optimally protected with a mildly acidic pH between 4.7 and 5.75. However, these values refer only to the surface of the skin. In the deeper layers of the skin, the values are higher.

The pH value is subject to certain factors and can therefore also change. In particular, gender, age, skin region and various external influences should be taken into account. An example involving infants: Shortly after birth, infants have a neutral to mildly alkaline pH value on the surface of their skin.

Normally, this value moves into the acidic range within the first month of life, which is important for the development of the skin barrier. Skin changes, such as rashes and irritation can occur until the protective acid mantle and the other defenses of the young infant's skin are strong enough.

By the way: If certain skincare products support the value range between 4.7 and 5.75, , you will often see a note saying: “This product is pH skin neutral”. Do not confuse this with pH neutral. This can be found in the description of products that are rated a 7 (water).

Why is proper skin care important? 

We talked about the structure and functions of the skin in another article, including how our skin serves as a kind of protective cover. Outwardly, skin acts as a barrier: it prevents pathogens and harmful substances from entering the body. Strong, healthy skin is important and the skin barrier should be as intact as possible. If the skin barrier is damaged, e.g. by pollutants, the probability of unwanted microorganisms, environmental pollution or even irritants (Skin-irritating substances) attacking the skin increases. 

To prevent damage to the skin or, more precisely, to protect the health of the skin, this mildly acidic pH value is of great importance. It not only ensures healthy and natural scaling of the skin, but also supports important enzymes. Some enzymes work best in the mildly acidic range and are important, for example, in the production of certain ceramides, which are key components of our skin barrier. The best pH for the skin also prevents harmful bacteria, fungi and other microorganisms from growing. This is the most effective way for the skin’s protective barrier to work. 

Overly frequent use of products that do not support or that disturb the balance of the average pH of the skin can have a negative effect on the acid mantle and also the condition of the skin. 

Look after yourself with the right mix of care, exercise and nutrition. Proper nutrition for skin & hair and maintenance of the skin’s natural pH (5.5) are both crucial.