Cyclopentasiloxane is an ingredient found in hundreds of personal care products. It improves the texture of formulations, giving them a smooth and silky feel.

Cyclopentasiloxane, also known as decamethylcyclopentasiloxane or D5, is part of the cyclomethicone family of silicones. It is a clear, odorless, thin liquid that a person may find in many skincare and cosmetic products.

Although it offers minimal benefits to the skin, manufacturers add cyclopentasiloxane to a vast range of products to improve their feel, delivery, and function.

This article discusses cyclopentasiloxane uses, benefits, and side effects in further detail. It also explores the impact of cyclopentasiloxane on the environment and alternative ingredients to consider.

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The primary function of cyclopentasiloxane is to work as an emollient. It can also give products a silky feel, which allows them to glide smoothly and deliver any active ingredients to the body evenly.

Manufacturers also use it as a solvent to help deliver active ingredients in a product to the skin or hair. However, unlike other silicones, cyclopentasiloxane is volatile, which means that it quickly evaporates and dries when applied to the skin.

Cyclopentasiloxane forms a protective barrier on the skin and hair, which is why many companies use it in antifrizz and detangling products.

It is also water-resistant. This is why companies commonly use it in sealants and windshield coatings.

A person may find cyclopentasiloxane in a wide range of personal care and cosmetic products, such as:

  • sunscreen
  • antiperspirant
  • deodorant
  • hair spray
  • shampoo
  • conditioner
  • antifrizz products
  • anti-hair-breakage products
  • hair-detangling products
  • pomade
  • makeup
  • makeup remover
  • night cream

Cyclopentasiloxane offers minimal benefits to the skin. Companies primarily add it to skincare products to improve their sensory feel and texture. However, it has other properties that boost the effectiveness of formulations.

Lightweight carrier

Cyclopentasiloxane is an effective carrier, or solvent, due to its ability to evaporate quickly. It helps to evenly coat the skin with active ingredients without leaving a heavy, sticky, or tacky residue after application. It leaves the active ingredients to work from the skin’s surface as they evaporate.

Forms a protective barrier

It also acts as an emollient that adds a protective barrier to the skin. However, it evaporates quickly and does not stay on the skin surface, so it does not leave a sticky feel. It leaves a protective yet breathable layer on the skin.

Facilitates a smooth application and delivery

Cyclopentasiloxane helps make formulations feel smooth and silky for a smooth and easy application. It allows products to spread evenly over the skin so that all areas of the skin receive key ingredients from a product.

Improves the appearance of scars

Many silicone gel preparations use cyclopentasiloxane as a carrier to deliver other silicone ingredients to the skin.

An older study found that silicone gel preparations improved the texture, height, and appearance of hypertrophic scars and keloids. However, it is important to note that the researchers conducted this study on a small sample size of 30 people.

Inexpensive

Cyclopentasiloxane is generally less costly than other silicone ingredients. Therefore, a person may find that products containing cyclopentasiloxane are more affordable.

Cyclopentasiloxane is generally well-tolerated and has no known side effects. The Cosmetic Ingredient Review Panel Board, an independent American body that assesses cosmetic ingredients, found the existing concentrations of cyclopentasiloxane safe to use.

The Environmental Working Group (EWG) also gives cyclopentasiloxane a grade of 3/10, with 10 being the most toxic. According to the EWG, the ingredient is unlikely to disrupt a person’s nervous system and endocrine system. Cyclopentasiloxane must enter the body to cause harm, which is unlikely because it evaporates easily.

An older study investigated the skin absorption of cyclopentasiloxane and found that the skin absorbed only 0.2%. Only 30% of the absorbed amount passed through the skin.

The European Commission’s Scientific Committee on Consumer Safety released a report in 2016 stating that aerosols, powders, hair-styling formulations, and body lotions with high concentrations of cyclopentasiloxane may cause aggregate exposure.

Aggregate exposure involves a person being exposed to one chemical, with exposure through the mouth (oral), skin (dermal), and nose (inhalation). The exposure comes from different sources, such as several cosmetic products containing high concentrations of the same ingredient.

The regulating body also recommended that cyclopentasiloxane should have at least 99% purity with no contamination from cyclotetrasiloxane (D4), a known endocrine disruptor.

While cyclopentasiloxane is generally safe for human use, it may have a negative impact on the environment.

Like other silicones, cyclopentasiloxane is a stable and nonreactive chemical, which means it can take years to decompose. It may evaporate into the air, or enter rivers and seas through drainage systems when a person rinses it off their skin or hair.

However, in 2012, the government of Canada found that cyclopentasiloxane did not enter the environment in conditions or quantities that make it harmful.

As a precautionary measure, in 2018, the European Union (EU) limited its concentrations in rinse-off products to up to 0.1%.

Research into the environmental impacts of silicones is ongoing.

A recent report found that around 4.7 tonnes of some silicones, including cyclopentasiloxane, enter surface water every year in the EU. The report stated that scientists have found cyclopentasiloxane and cyclotetrasiloxane in the blood plasma of fish, birds, and mammals.

Furthermore, the authors of a 2021 review found that silicone levels are higher in industrial areas where silicones are more likely to transform into different chemicals. The authors concluded that further studies into the concentrations of silicones in industrial areas are necessary.

To discover more evidence-based information and resources for the environment and sustainability, visit our dedicated hub.

Many companies are innovating other silicone and silicone-free alternatives to cyclopentasiloxane in light of the recent EU restriction.

Botanical oils and waxes may be possible natural alternatives. However, these substances can soak into the skin and leave a heavier feel. Therefore, they may not be suitable for people with sensitive skin types.

Water-soluble silicones do not have the same disadvantages as dimethicone or cyclopentasiloxane and may be a possible alternative. However, they are more expensive to produce.

Silicone-free alternatives are also on the rise. These include products such as plant-based and vegan dimethicone and cyclomethicone alternatives, made by manufacturers such as Inolex, which mimic the spreading and emollient properties of cyclopentasiloxane.

Learn more about organic skin care here.

Cyclopentasiloxane is a popular ingredient in many cosmetic products. It helps to evenly distribute products and makes hair or skin feel smooth and silky.

Many organizations consider it to be safe in cosmetic products. Numerous studies and reports suggest that the body does not absorb the ingredient, and it does not cause serious health problems at its available concentrations in cosmetics.

Some countries have imposed higher restrictions on the amount of cyclopentasiloxane in rinse-off ingredients as a precaution against accumulation in water supplies, which can impact marine life.

A person looking for different ingredients may find many new types of water-soluble silicone and silicone-free alternatives.