Updated 10/12/20 If you’re prone to breakouts, then you surely pay attention to ingredient labels when buying new skincare or makeup products. Those with blemish-prone skin are often very focused on avoiding pore-clogging ingredients (rightfully so). One group of ingredients that has gotten quite a bad reputation for clogging pores is silicones. But do silicones really cause blemishes, and should they be avoided by those with acne-prone skin?
The simple answer is, no. Most silicones are agreeable with skin types that are prone to clogged pores and blemishes. It all comes down to which kind you use, as well as what other ingredients are in the formula, as I’ll explain.
Despite recent confusion, silicones are also very safe ingredients. I spoke with Ron Robinson, a cosmetic chemist and founder of Beauty Stat about the safety of silicones. “With the clean beauty movement, some companies deem silicone-containing products as not fitting their clean standards,” Robinson said. “I disagree with this theory given the amount of data on silicones compared to many other natural ingredients that are considered clean, yet have little data to support this.”
What’s the Deal With “Comedogenicity?”
Comedogenicity is a term that gets thrown around a lot in skincare, so first, let me define what it actually means.
“Comedogenic” is a technical term for “pore-clogging.” Since many of my products are designed to manage acne-prone skin, I’ve studied comedogenicity extensively in my cosmetic chemistry courses as well as in the lab when formulating products. Essentially, comedogenicity refers to how likely certain topical agents (primarily emollients) are to cause the development of comedones. A product or ingredient that causes comedones to develop is considered comedogenic.
In oily skin types that are prone to clogged pores and acne, cell buildup (also called retention hyperkeratosis) occurs on the follicle walls. Dead cells build up and are coated by oil, which is being over-produced in this skin type. Acne bacteria feed off fatty acids, which they break down from your skin’s natural oils. It’s true that when applied to the skin’s surface, SOME oils and emollients further coat these follicle walls. This can potentially exacerbate breakout conditions. For people who do not experience issues with blemishes (such as dry skin types), the use of these heavier ingredients should not be a problem at all—and in fact, can actually help to repair dryness.
Facts About Silicones
There’s a lot that people don’t know about this ubiquitous group of ingredients, so here’s a brief introduction to silicones and what they do:
- They are used in skincare and makeup products to deliver a smooth, soft, velvety texture to the skin
- They help deposit active performance ingredients, color, and fragrances evenly over the skin
- They optically diffuse light to soften the look of wrinkles and pores
- They are a class of ingredients, so you’ll never see just the word “silicone” listed
- Not all silicones remain on the skin after you apply them due to the different rates of volatility*
- They have far more benefits than risks
- The most common types used in makeup and skincare are cyclopentasiloxane, dimethicone, dimethiconol, Cyclomethicone, cyclohexasiloxane, and cetearyl methicone.
*Volatility can best be described as the degree to which a molecule wants to be airborne into the atmosphere. It’s the speed of the ingredient evaporation. Usually, smaller molecules want to be airborne (example: isopropyl alcohol) and the heavier ones don’t (example: Vaseline). You can correlate volatility with weight.
PROS of Silicones
- Hypoallergenic and won’t sensitize the skin, making them ideal for easily irritated complexions
- Silicones themselves will not clog the pores
- Give a beautiful silky feel when spread over the skin
- Soften the look of fine lines and wrinkles
- Will offset dryness caused by harsh acne products such as benzoyl peroxide and topical antibiotics
- Can help manage flakiness and cracking of the skin in those with eczema and psoriasis conditions
- Won’t leave a greasy feel, making it ideal for oily skin types where a lightweight formula is desired
- Protects skin from environmental pollutants by creating a “breathable” barrier over the skin while still allowing nitrogen, oxygen, and water vapors to pass through
- They help prevent transepidermal water loss (TEWL) to keep skin feeling moist even in dry climates like airplanes or the desert
- Can increase penetration of other ingredients used in a product (can also be a con, see below)
CONS of Silicones
- Can increase the penetration of some other ingredients used in a product, which could lead to clogged pores. If there are ingredients in a formula that aren’t compatible with oily, acne-prone skin types (like some lipid-rich plant oils used in high concentrations), the silicone ingredients may facilitate a blockage in the pore lining. This is what can potentially lead to clogged pores and blemishes, not the silicone itself. Note: Not all silicones have the ability to do this, as I’ll describe below!
Silicones Beneficial For Oily, Blemish-Prone Skin
These silicones are lightweight and have relatively high volatility. This means they have a tendency to evaporate and don’t linger on the skin or create an occlusive barrier.
Cyclopentasiloxane is lightweight and allows skincare products to glide nicely onto the skin without leaving a greasy feeling. After a few moments, it evaporates from the skin, leaving the other ingredients behind. Anyone concerned about products creating an occlusive barrier shouldn’t worry about cyclopentasiloxane in their formulas because it essentially just acts as a carrier then goes away.
This silicone is a blend of cyclotetrasiloxane and cyclopentasiloxane, which have high volatility making them evaporate after some time. This makes Cyclomethicone non-occlusive and perfectly safe for oily, blemish-prone skin types.
Cyclohexasiloxane is a blend of siloxanes with fairly high volatility, so it should evaporate off the skin and be easily tolerated by oily, blemish-prone skin types.
Silicones NOT Beneficial For Oily, Blemish-prone Skin (But Good For Other Skin Types)
These silicones have low volatility, meaning they don’t really evaporate off the skin and can create an occlusive barrier that may not be ideal for those prone to clogged pores. Remember that this doesn’t make them “bad” ingredients—these silicones are still excellent choices for those with dry skin types.
Dimethiconol has low volatility and doesn’t really evaporate. This is beneficial if you want it to stay on the skin to help correct dryness and prevent moisture evaporation from occurring.
This is a soft silicone wax that coats the skin. It provides a lot of slip to a formulation but it’s not volatile, so it would be considered a good occlusive for dry skin types in need of moisture repair. This means, however, that it’s not ideal for those prone to breakouts.
NOTE: To reiterate, it’s NOT the silicone that is the issue. It’s only if the formula includes other heavy, rich ingredients that the silicone allows to be pushed deeper into the pore. So if there are not other heavier ingredients used in a formula, then these silicones technically shouldn’t cause problems in blemish-prone skin.
Silicones That Could Be Good OR Bad for Oily, Blemish-Prone Skin
Sometimes, you just can’t tell from an ingredient label how likely a silicone is to lead to clogged pores. It may depend entirely on how the silicone is formulated, as is the case with dimethicone.
This one is quite complicated because it can have many different weights. A formulator can use dimethicone that’s extremely volatile, where it evaporates off the skin within seconds making it safe for oily skin types. Or, a formulator may use dimethicone that’s extremely heavy with no volatility, causing it to stay on the skin and carry other potentially pore-clogging ingredients into the pores. It’s almost impossible for me as a formulator, let alone you as a consumer, to look at an ingredient label and know which weight of dimethicone was used. The bottom line? You can’t form assumptions when seeing dimethicone on an ingredient list.
The Silicone Test
Last year when I did a blog post about liquid foundations, I did an oil migration test to help me draw some semi science-based conclusions as to which ones were the best for oily, acne-prone skin.
I wanted to do a similar demonstration with silicones. My goal was to provide you with a visual representation of how differently various silicones can act on your skin based on their composition. I decided to get science-y again to show you some visuals:
To begin, I got samples of three different silicones from the lab and put a few drops of each on paper. As you can see, I tested cyclopentasiloxane as well as two different dimethicone samples—one with a low molecular weight and one with a high molecular weight.
After 45 Minutes
After 45 minutes, you can start to see how long each silicone stays in its form. This is an indicator of volatility (the rate at which something evaporates). You can also see that the more volatile formulas spread out more before evaporating, which might influence how and when a cosmetic formulator decides to use them.
One thing you can’t tell from the photo is the consistency of each silicone. Both the cyclopentasiloxane (on the left) and the highly volatile dimethicone (in the middle) are the consistency of water but with a slippery, silky feel. The non-volatile dimethicone (on the right) is a thicker consistency like that of syrup, but also with a silky feel.
After Two Hours
After two hours, both the cyclopentasiloxane and the more volatile dimethicone had evaporated entirely. This indicates that they would not coat the skin as much as the higher molecular weight dimethicone on the right. The dimethicone on the right would be better for staying in place and creating an occlusive layer over the skin.
The first two silicones are fast-drying and would not provide a long-lasting occlusive effect, so neither should be problematic for clogged pore-prone skin. Both would give products a nice, smooth texture and good spreadability.
The dimethicone on the right has a higher molecular weight than the first two silicones, so it would coat the skin instead of evaporating. It is an occlusive and would create a barrier, making it ideal for dry skin but not for oily skin—especially if there are other pore-clogging ingredients used within the same formula.
Needless to say, not all silicones are created equal. I hope this demonstration gives you a glimpse into just how differently various silicones can act on the skin. There is so much variation among the ingredients that fall under the umbrella of ‘silicones’ and there’s no reason to swear them all off. It’s just about choosing the ones that are compatible with your skin type.
Are Silicones Biodegradable?
It depends on which type of silicone and what it is functionalized with. Some are not readily biodegradable, which means they will eventually biodegrade but it takes time depending on a few factors. Other studies show that silicones can accumulate in the environment (water) and that they’re not readily biodegradable. It’s a big debate in our industry because there are many conflicting studies.
So Should I Use Silicones On My Skin?
If you like the look and feel of your skin when you use silicone-based products then keep using them. However, if you think a silicone-based product might be causing breakouts, it could very well be from another ingredient in the formula. I recommend that you try a different formula but not rule out silicone entirely.
The most important point I’d like to make about skincare formulas is that you can’t judge a product by an ingredient label. The results a product delivers (positive or negative) are based on your unique skin, as well as the percentages of the ingredients used in a product—and you’ll never know these percentages from looking at the list on the back of a bottle or jar. Simply put, you can’t tell the true results of a product until you actually try it. This is why I always suggest only introducing one new product at a time, as well as doing a patch test before you use it over your entire face. This way, if your skin responds negatively, at least you can pinpoint which product it might be.
A big thank you to Valerie George, cosmetic chemist, and co-host of The Beauty Brains podcast for giving me additional insight for this post!
Celebrity Esthetician & Skincare Expert
As an esthetician trained in cosmetic chemistry, Renée Rouleau has spent 30 years researching skin, educating her audience, and building an award-winning line of products. Trusted by celebrities, editors, bloggers, and skincare obsessives around the globe, her vast real-world knowledge and constant research are why Marie Claire calls her “the most passionate skin practitioner we know.”