PEG (polyethylene glycol) is an ingredient used in many cosmetic products.
It is a useful ingredient that acts as a moisturizer, emulsifier, thickener, etc.
I'd like you to check if it's in the cosmetics you have on hand...
If it is included, there will be a number after "PEG."
What numbers are written on it?
This number represents the molecular weight of the PEG.
In simple terms, the smaller the number (molecular weight), the smaller the size of the PEG and the greater its ability to penetrate the skin.
When you hear that it penetrates the skin, some people might think, "This will make my skin beautiful!"
However, in reality, for sensitive skin, high permeability can cause irritation or stinging.
Skin permeability of PEG
As mentioned at the beginning, the characteristics of PEG vary depending on the number at the end (molecular weight).
A smaller number for PEG indicates a smaller molecular weight.
This means that it easily passes through the skin barrier, which is why it is sometimes used in combination with other ingredients to deliver them deeper into the skin.
On the other hand, a larger number for PEG means a larger molecular weight.
Because they are larger than skin cells, they cannot penetrate as deeply.
Therefore, it stays on the surface of the skin, preventing it from drying out and helping to maintain moisturizing effects.
Be careful with the size of PEG for weak skin
However, skin penetration is not determined solely by the size of the numbers.
It actually depends on your skin condition.
People with sensitive skin, atopic dermatitis, inflamed skin, and the skin of small children should be careful.
In other words, if you have sensitive skin or a weakened barrier function, you should be a little more careful.
This is because ingredients that are difficult to penetrate into healthy skin can slip through the broken skin barrier in weakened skin.
Regardless of the size of your PEG, you may be more susceptible to irritation.
PEG helps carry other ingredients deeper into the skin.
However, it's not just ingredients that are good for the skin that are delivered in this way.
Similarly, ingredients that are highly irritating to the skin, such as preservatives and fragrances , as well as allergens, are transported deeper into the skin.
How to determine the size of your PEG
So how can you tell the size of your PEG?
This is surprisingly easy. Just check the number after PEG listed on all ingredients.
The smaller the number, the smaller the PEG (low molecular weight) and the more permeable it is. Conversely, the larger the number, the larger the size (high molecular weight) and the less likely it is to penetrate the skin.
<Example>
・PEG-6, PEG-8, PEG-12, etc.
| These are very small PEGs that have high permeability and are often used in lotions, beauty serums, sheet masks, and other products to deliver beauty ingredients deep into the skin. People with sensitive skin should be careful as it may cause skin irritation. |
・PEG-600, PEG-1000, PEG-6000, etc.
| These are large PEGs. They remain on the surface of the skin, so they are used in moisturizing creams and bath salts for their moisturizing effect. They form a barrier on the surface of the skin to prevent moisture from evaporating. Because it does not penetrate easily, it tends to cause less irritation to the skin. |
In general, PEG with a molecular weight of 300 to 400 or less is said to be easily absorbed into the skin.
In other words, if you are prone to skin irritation, make sure the number after PEG is not higher than 400!
Side effects of PEG
PEG is generally considered to be a skin-friendly and safe ingredient, so it is not uncommon for it to be included in cosmetics for sensitive skin and children.
If you pay attention to the size of the PEG, you may be able to avoid the risk of skin irritation. However, there are other risks associated with PEG that you should be aware of.
For more details, please read the article below if you are interested.
Related article 1: Polyethylene glycol (PEG): Why you should avoid it in cosmetics
Related article ②: Safety of PEG-60 hydrogenated castor oil: Precautions when using and risk of impurities
I hope this article will be of some help to you in choosing cosmetics that you can use with greater peace of mind.
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"CONCIO" - A company that thoroughly researches the risks of cosmetic ingredients
CONCIO is the first additive-free skin care product in Japan to receive EWG certification, meeting new standards.
Focusing on the risk of skin irritation and allergies caused by cosmetic ingredients, we strictly adhere to our own safety standards and do not use 2,500 ingredients.
We deliver world-class peace of mind to sensitive skin in Japan.
*This does not guarantee that skin irritation or allergies will not occur in all people.
