Silicones in hair: what they are, what they're for, and whether you should avoid them

Silicones are polymers formed by siloxane bonds (Si–O–Si) that are widely used in shampoos, conditioners, and styling products for their ability to protect, soften, and add shine to hair. A recent scientific review article objectively analyzes their function, advantages, and controversies in modern hair care.

What do silicones do for hair?

Silicones form a very thin film around the hair fiber. This layer reduces friction when combing, decreases breakage, helps retain moisture, and improves shine and manageability. For this reason, they are often recommended for damaged, color-treated, or heat-exposed hair, where the cuticle is more vulnerable.

Common types of silicones

The article explains that not all silicones are the same:

• Water-insoluble silicones (like dimethicone): offer high conditioning, but can lead to buildup if not removed properly.

• Water-soluble or dispersible silicones: rinse out more easily and reduce the risk of residue.

• Volatile silicones: evaporate after application, leaving a lightweight feel.

• Amino-functional silicones: selectively adhere to the most damaged areas of the hair, conditioning only where needed.

Additionally, so-called fourth-generation silicones incorporate encapsulation and controlled-release technologies, aiming for the same performance with a lower environmental impact.

Controversies: buildup and the environment

The main criticism of silicones is buildup on the hair, especially with insoluble types. To remove them, shampoos with stronger surfactants are often required, which, if used in excess, can be drying. Regarding the environment, some cyclic silicones have been questioned for their low biodegradability, which has prompted regulations and new, more responsible alternatives.

Should you use them or avoid them?

Scientific evidence does not support the idea that silicones “suffocate” the hair. The current consensus is that their use should be intelligent and personalized: alternating products with and without silicones, using clarifying shampoos occasionally, and choosing the right silicone based on hair type (fine, curly, thick, oily).

Natural alternatives to silicones

For those who prefer silicone-free formulas, there are plant-based ingredients that can offer similar benefits, albeit with a different sensory profile. Some examples include light oils (jojoba, argan, plant squalane), natural esters derived from coconut or sugar, and refined butters in low concentration. These ingredients help to soften, seal in moisture, and add shine, without creating the same buildup as certain traditional silicones. The key is a well-balanced formulation adapted to the climate and hair type.