Phenoxyethanol, a toxic preservative

In this blog, I use citations from scientific research - so you can see there is no information manipulation. 

I want to bring awareness to something that I feel is important. I am a real person and I care so much – for people's skin and health. 

One of human skin's main properties is to be a physicochemical barrier to the environment. It  protects us from the environment and stops large molecules from entering our body. There is now however more understanding about how smaller molecules can penetrate the dermal layers.


  1. The 500 Dalton rule of dermal penetration

In 2000, research in the Netherlands was conducted in the context of dermatological therapy. It was led to inform the development of future drugs and compounds with topical application method in a medical context. The research showed that ingredients with a molecular weight under 500 Dalton have the ability to penetrate skin (dermal layers). 

The conclusion was confirmed through the analysis of 3 situations:

  • All common contact allergens (molecule that cause an allergic reaction when in contact with skin) are under 500 Dalton.
  • Clinical experience with topical agents such as cyclosporine, tacrolimus and ascomycins show that the molecular weight of the ingredients needs to be under 500 Dalton.
  • Topical drugs used in transdermal drug-delivery systems are under 500 Dalton. 


Source: The 500 Dalton rule for the skin penetration of chemical compounds and drugs. Bos JD, Meinardi MMHM, 2000


  1. Molecular weights of popular skincare ingredients

Here is a list of popular skincare ingredients and their molecular weights:

  • Glycerin: 92 Dalton
  • Ethanol: 46 Dalton
  • Water: 18 Dalton
  • Caprylic/Capric Triglyceride: 408 Dalton
  • Lactic Acid: 90 Dalton
  • L Ascorbic Acid: 176 Dalton
  • Retinol: 286 Dalton
  • Retinol Palmitate: 524 Dalton
  • Phenoxyethanol: 138 Dalton


Phenoxyethanol has a relatively low molecular weight, and therefore can be absorbed by skin.

  1. Understanding Phenoxyethanol

Phenoxyethanol is a molecule that is synthetically manufactured. It is the most popular preservative for skincare products. If you start looking at products on shelves or in your bathroom cabinet, you might be surprised how many products have it on their ingredient list.

It is considered an irritant by the Library of Public Medicine, highlighted for its toxicity to respiratory system in high dose. Here is an extract of its safety data sheet:


Typically, phenoxyethanol's concentration in skincare products is around 1%. 

Did you know that water represents about 90% of what makes skincare products? This leaves 10% for active ingredients (like vitamin C, retinol...) and non-active ingredients (like thickeners, polymers...).

To understand a product formula, it is important to remove water from it. It gives you the true product make-up and its potency. By doing so, we have a different picture: Phenoxyethanol is likely to be around 10% of what makes a skincare formula.

If you speak to any skincare formulator, it is not a small amount.

If your skincare products have phenoxyethanol and you use them morning and night, your skin is constantly absorbing phenoxyethanol. 

In summary:

  • Phenoxyethanol has a molecular weight under 500 Dalton, which means it is absorbed into skin.
  • It is an irritant and considered toxic to skin and health.
  • It is in higher proportion than it seems in skincare products.
  • It is present in the majority of skincare and body care products.
  • Most of us constantly have been feeding our skin with the toxic preservative for most of our lives.



I understand why phenoxyethanol is used and how it prevents products from molding, but I feel we should be be more careful about our overall exposure to it.

I believe there is a way to make skincare products work effectively without it. It is a matter of understanding the stable forms of ingredients, and keep their integrity in the skincare formulas that we develop.

In my next blogs, I will explore the "natural" versions of phenoxyethanol. I will also explore my position on the inclusion of water in skincare formulas.

Thank you for reading,