Silicone Quaternium-20: What Is It, Cosmetic Uses, Benefits & Side Effects

Curious about this ingredient? In this article we're explaining exactly what it is and why it's used within cosmetic formulations.
Updated on: June 30, 2025
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We verify all information on this page using publicly available nomenclature standards from The Personal Care Products Council (PCPC), the European Commission's CosIng database and documentation provided directly by ingredient manufacturers. Our analysis is based on technical data from these sources to ensure accuracy and reliability.

What Is Silicone Quaternium-20?

Silicone Quaternium-20 is a man-made, water-dispersible silicone that carries a positive charge. Chemists create it by bonding a silicone backbone to a quaternary ammonium group, giving the molecule its conditioning abilities and its name. This cationic nature helps the ingredient cling to the slightly negative surface of hair and skin, forming a light, protective coating.

The compound first gained traction in the 1990s when formulators looked for silicones that could rinse out more easily while still giving the smooth feel customers expected. By attaching the quaternary group, scientists made a silicone that spreads well in water-based products and feels less heavy than older silicone oils.

Production starts with a silicone polymer that is reacted with a quaternary ammonium salt. The result is a viscous liquid or soft wax that blends into water or alcohol systems with gentle stirring. Because it is pre-neutralized, it slots into a formula without extra pH adjustments, saving time on the factory floor.

You will most often see Silicone Quaternium-20 in rinse-off and leave-in hair conditioners, shampoos, masks, serums, heat protectant sprays, body lotions, hand creams and lightweight facial moisturizers. Its ability to condition without a greasy afterfeel makes it popular in products aimed at fine or combination hair and skin types.

Silicone Quaternium-20’s Cosmetic Benefits/Uses

Formulators rely on this ingredient for two main reasons

  • Hair Conditioning: The positive charge helps the silicone align along damaged spots on the cuticle, smoothing rough edges and reducing static. This makes combing easier, boosts shine and leaves hair feeling soft but not coated.
  • Skin Conditioning: On skin, it lays down an even, breathable film that traps moisture yet feels silky, not oily. The result is a quick slip during application and a velvety finish that can enhance the overall sensory profile of creams and lotions.

Who Can Use Silicone Quaternium-20

Silicone Quaternium-20 is generally well tolerated by all skin and hair types. Its lightweight, water-dispersible film makes it a good fit for oily or combination skin because it conditions without leaving a greasy residue, while dry or mature skin benefits from the added softness and moisture retention. Sensitive skin usually handles it well, though anyone with a known silicone allergy should avoid it.

The ingredient is produced entirely from synthetic raw materials, so it contains no animal-derived substances. This means it is suitable for vegans and vegetarians provided the finished product is certified cruelty free by the brand.

Current safety data show no reproductive or developmental risks from topical use, so products containing Silicone Quaternium-20 can be used by individuals who are pregnant or breastfeeding. This is not medical advice and anyone in these groups should confirm suitability with a healthcare professional before adding a new product to their routine.

The molecule does not absorb UV light or alter skin sensitivity to sunlight, so it is not considered photosensitising. It is also non-volatile and fragrance free, qualities that further lower the chance of irritation.

Potential Side Effects/Adverse Reactions

Responses to Silicone Quaternium-20 vary from person to person. The effects below are possible but uncommon when the ingredient is incorporated correctly in a cosmetic formula.

  • Mild skin redness or itching in people with silicone sensitivities
  • Transient scalp or facial buildup that can weigh hair down or give skin a filmy feel if the product is not rinsed thoroughly
  • Eye irritation if the product accidentally gets into the eyes
  • Acne-like breakouts on very clog-prone skin, especially if layered with heavy occlusives

If any discomfort or adverse reaction occurs discontinue use and consult a medical professional.

Comedogenic Rating

Rating: 1 out of 5

Silicone Quaternium-20 is water dispersible and forms a breathable film that sits on the surface of skin rather than sinking into pores. The molecules are large, positively charged and unlikely to mix with sebum, so they rarely cause blockages. Studies and user feedback show few true comedones, though very oily skin can notice a slight residue if the overall formula is heavy.

With a score of 1 it is generally suitable for acne-prone or breakout-prone users. If congestion appears it is more likely due to richer accompanying ingredients than to Silicone Quaternium-20 itself.

Regular cleansing removes the light film it leaves which further limits clogging risk.

Summary

Silicone Quaternium-20 works as a hair and skin conditioner, spreading a thin positively charged silicone layer that smooths cuticles, reduces static, increases slip and helps lock in moisture while feeling weightless. Because it disperses in water it blends easily into shampoos, conditioners, lotions and serums and rinses out more cleanly than older silicones.

It is not as well known as dimethicone but enjoys steady popularity among formulators who want a lighter touch and good rinse-off performance, showing up most often in modern hair care and gel creams.

Safety assessments find it non irritating and non sensitising at the levels used in cosmetics, so it is considered low risk for everyday use. Still it is smart to run a quick patch test when trying a new product containing this ingredient just to make sure your skin stays happy.

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