What it does
The EU's CosIng database lists two functions: hair conditioning and antistatic. It describes the ingredient as a dimethylsiloxane polymer whose ends carry aminoethyl-aminopropyl groups1, which is why reviews call it an amino-functional silicone.2
Those amine groups are the point. In water they become positively charged, so the silicone deposits onto the hair cuticle, whose protein surface is negatively charged.3 A 2025 review describes it binding selectively to the most damaged areas of the hair shaft.2 Bleached and chemically treated hair has more negative sites and is more porous than untreated hair, which gives it a higher affinity for conditioning ingredients in general.4
Not every source goes as far. A 2015 review cautions that amino silicones are not necessarily more substantive to hair than Dimethicone: it depends on the size of the molecule and the charge of the whole formula.4
Where you find it
In hair products. Shampoos pose a problem for silicones, because their surfactants wash conditioning silicones away; amodimethicone's positive charge is one way formulators get a silicone to deposit anyway, and aminosilicones are among the main ingredients of two-in-one shampoos.3 A 2025 review also suggests amino-functional silicones for curly or textured hair, saying they can improve definition and reduce dryness.2
Build-up, and what sources say
Amodimethicone does not dissolve in water. The 2025 review lists it with dimethicone among the silicones that may accumulate if they are not properly cleansed, and notes that removing water-insoluble silicones takes strong surfactants, which can be harsh on delicate or textured hair.2 It gives no figure for how often this happens.
The US Cosmetic Ingredient Review assessed amodimethicone together with dimethicone and other silicone polymers, and considered significant absorption into the skin unlikely because of their large molecular weight.5 Amodimethicone has no entry in the annexes of the EU cosmetics regulation.6
How it appears on a label
As Amodimethicone, its name in the EU glossary.7 Related amino silicones carry names such as Aminopropyl Dimethicone, assessed in the same US review.5 Because it is a silicone, EU claims guidance says a product containing it should not be called silicone-free.8
For how it compares with dimethicone and the volatile silicones, see silicones in hair products. To see what every other name on a list does, use the ingredient checker.