Octamethyltrisiloxane is a commonly used silicone-based polymer, also known as dimethicone. In personal care products, it is often used as a base ingredient in cosmetics such as lotions, moisturizers, sunscreens, and hair masks.

Its functions include:
- Increases the smoothness and ease of spreading of the product, making it easier to apply the product on the skin without leaving a sticky feeling.
- As an emollient, it can improve the smoothness of the skin surface, reduce the loss of water from the skin, and help keep the skin moist and soft.
- In sunscreen products, octamethyltrisiloxane can improve the uniformity and stability of the product, while enhancing the water resistance of the product.
- In a hair mask, it coats each strand to restore texture and add shine without leaving hair greasy.

It should be noted that the use of octamethyltrisiloxane should be controlled within an appropriate concentration range, too high a concentration may cause irritation and adverse reactions to the skin