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What is cyclopentasiloxane

Kalisa’s quest: The last time I was having my hair done, I asked my stylist to help me find some product for my hair. I told him that I’d tried several different things, but I just can’t achieve the look I’m going for. I want to know how to get that slightly wet, slightly “greasy” look, without it being “crunchy,” and he said, “You need a product with silicone” and sold me something [Bumble & Bumble defrizz] with “cyclopentasiloxane” as the main ingredient. Why do you suppose he recommended silicone and what purpose does it serve in a hair product?

The Beauty Brains respond:

We’re glad your stylist recommended this silicone because it’s one of our mostest favorite ingredients in the whole wide world! In fact, the Left Brain has even written a short musical tribute to Cyclopenatasiloxane (or ‘Siloxane, as we like to refer to it.) I’m not really supposed to share it with you, but what the heck….

(sung to the tune of the “Troggs’ Wild Thing”)

‘Siloxane…you make my hair shine…

You make everything


I said ‘Siloxane…

‘Siloxane, I think I love you

But I wanna know for sure

Comb in, hair is bright

I love you

It kind of brings a tear to your eye, doesn’t it? Now, on to your answer.

Why is cyclopentasiloxane used in cosmetics?

Cyclopentasiloxane (or CPS for short) is one of many types of silicones. In general, silcones are known for their ability to lubricate, waterproof and provide shine. (Think “Armor All” for your head.) There are many types of silcones – some have a very heavy, sticky consistency and others are very lightweight. CPS is a water-thin so it’s very good at dispersing thicker, greasier silicones. For this reason it’s often used in combination with dimethicone. It is also volatile, which means it will evaporate. So, not only does it help spread heavier silicones but it doesn’t leave your hair feeling weighed down after it’s done.

In rinse off products CPS is used to create a very lubricious, wet slippery feel. In the kinds of leave on styling products that you asked about, it can give you the wet but not crunchy look you’re seeking. Of course, the other ingredients in the formula make a difference too, but that’s why your stylist recommended something based on CPS.

The Beauty Brains bottom line:

CPS is one of our fave ingredients – it provides a very elegant feel on the hair, it works well with other ingredients, and it can be used in leave on and rinse off products. What more could you ask for from an ingredient?

{ 18 comments… add one }

  • Big beauty bitch December 2, 2013, 1:52 am

    U r stoopid n sutf cuz ur liek saying gud things abut cyclopentasiloxane wen its actully rlly bad for u

    • Randy Schueller December 2, 2013, 2:26 pm

      This is one of my most favorite comments ever!

    • Nyasha February 8, 2015, 2:37 am

      This comment is more stupid. Come back when you can spell please. Thank you editors for providing this. I just want to know whether it can have negative impacts on hair growth?

      • Randy Schueller February 8, 2015, 8:43 am

        We’ve never seen any data showing that cyclopentasiloxane has an effect on hair growth.

  • Lalo Bean December 17, 2013, 8:57 am

    I was curious about this chemical as well and found the following information:
    “The city of San Francisco on its environmental website warns that “effects of D5 include impacts to the nervous system, fat tissue, the liver (bile formation), and the immune system. Exposure to D5 is known to aggravate liver disorders and cause liver weight changes in rats exposed to it. Should this combustible solvent ignite and start a fire, one of the resulting products is formaldehyde, an acute respiratory and nervous system toxicant and cancer hazard.” Also, because D5 is an environmental contaminant, humans could be exposed to it by consuming wildlife and fish that ingested it.”

    Kinda makes me want to use it NOT SO MUCH … eh?

  • LaloBean December 17, 2013, 9:05 am

    BTW you also said ” For this reason it’s often used in combination with dimethicone.”

    “Expectant and breast-feeding mothers are advised to consult a physician before using any product that contains dimethicone. It is possible for a consumer to find out if dimethicone, or one of its variants, is present in a particular product by reviewing the list of ingredients. Names such as Amodimethicone, Stearoxy Dimethicone and Behenoxy Dimethicone indicate the use of polymers based on this manmade substance.
    Side Effects

    Some side effects have been reported from the use of PMDS products; they include mild itching and stinging or burning sensations. Allergic reactions such as hives, sudden respiratory problems, and swelling in any part of the mouth or face represent can also happen. Users of dimethicone creams may be surprised to find that the product can actually worsen dryness in some individuals. This is not necessarily a sign of ineffectiveness, but may instead indicate an allergic reaction that should not be ignored.

    Should such symptoms appear, doctors recommend immediately discontinuing use of the product. Seeking medical attention is a good idea if the reaction becomes severe, or does not improve quickly. A pharmacist can be another good resource for guidance regarding side effects. ”
    info above gleaned from:


    • Randy Schueller December 17, 2013, 10:44 am

      Lalo: The kind of reactions to dimethicone that you described are quite rare. (The Wisegeek article doesn’t provide any technical references so I can’t track down the details.) But dimethicone is approved as an Over the Counter skin protectant drug and it is proven to REDUCE dermatitis (see this link for references: http://www.ncbi.nlm.nih.gov/pubmed/?term=dimethicone+dermatitis)

  • Mel January 20, 2014, 9:42 pm

    I wish we could go back to the days where everything in our shampoo wasn’t a petrochemical byproduct that bioaccumulates and causes all kinds of horrible things to happen to rats in studies…wasn’t there ever a time when soap was just…pronounceable?

    • Randy Schueller January 21, 2014, 6:01 am

      I understand your frustration but please don’t fall for the misconception that “all natural is good; all synthetic is bad.” PS The pronounceability of an ingredient does not correlate to its safety.

      • Artemis May 8, 2014, 5:27 pm

        You’re so right, I always say that. The name thing is stupid cause even natural things have long names(like the latin names of plant extracts, for example) and SOAPS do contain a lot of long ingredients, too. Also, a lot of natural stuff like mint, for example, is irritant.

  • Andrea January 29, 2014, 1:51 pm


    I was wondering if you can help with my dilemma. I have eczema and many allergies. I found out by trial and error I am allergic to silicones including dimethicone. Are there many products out there that don’t have silicones? I’m talking about makeup, hair and skincare. I also seem to be really allergic to it considering I had a teeth impression made from a mold and had a coughing fit and throat swelling. It turned out the mold ingredients was comprised of silicones which I had in my mouth for about ten minutes (5 for each upper and lower teeth). After taking allergy medication I felt better but was really bothered by this fact. I know we don’t usually EAT silicones but the fact that I reacted so badly frightened me. Any advice on which products to look into?

    • Randy Schueller January 29, 2014, 2:51 pm

      Hi Andrea. The best thing you can do is keep an eagle eye on the ingredient lists of products before you use them. Here’s a link to a post where we list many of the most common silicones. Hopefully this will help you know what to avoid:


    • A blissful place wellness March 26, 2015, 2:36 pm

      Hi Andrea,
      I’ve been reading this string and suffered from eczema among other major skin issues before I became an estetician 22 years ago. My heart goes out to anyone dealing with this and I can’t stand when people just recommend ANOTHER skin care product.
      The ONLY way to truly deal with it is integrative. Meaning you need todo 2 things internally, 2 topically and 2 mentally.
      Call or visit our website at http://www.ablissfulplace.com. I’ll give you a 1 month free membership and get you started at Truly ending your eczema.

  • Mandy April 7, 2014, 9:23 am

    BeautyBrains to the rescue again! I recently dyed my hair and the conditioner included in the box has proven to be nothing short of amazing (a happy surprise), so I read the ingredients and went in search of a conditioner that has the main ingredient (Cyclopentasiloxane) as one of it’s top 3, but first I wanted to make sure it was actually a good ingredient, and not just my mind playing tricks on me. Thanks!

    • Randy Schueller April 7, 2014, 10:05 am

      That’s what we’re here for, Mandy!

    • Linda April 7, 2014, 4:39 pm

      The first ingredient in the following product is cyclopentasiloxame (2nd is dimethicolol):
      L’Oreal Oleo Therapy Perfecting Oil Essence–it’s available at Ulta.

  • Robin April 22, 2014, 7:04 am

    This is the dominant ingredient in Clinique Moisture Surge Intense. Works well for my ultra dry skin. Do you think it is safe for skin? Thank you.

  • Elizabeth November 4, 2014, 10:36 pm

    I love learning the scientific words and their definitions. Cyclopentasiloxane is a great word. I see some people have allergies to ingredients, but often it’s an added ingredient or filler that is causing a reaction. That the combination of ingredients that overall don’t suit all skin types, causes unsuitable results. Live the scientific education going on here.

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