Dimethicone is usually OK for acne prone skin. Dimethicone is one of the “Silicones”. These ingredients are used in skin care products to deliver a smoother and softer skin texture to the skin. They optically diffuse light to soften hard edges of pores on the skin’s surface, making the skin look radiant and glowing.
Dimethicone as the other silicones is hypoallergenic and non-comedogenic and are not known to sensitize the skin. They are also excellent at offsetting dryness from acne products such as benzoyl peroxide that can cause flakiness but will not make the skin greasy.
Beware that If there are other ingredients in a formula that aren’t compatible for oily, acne-prone skin types (like some lipid-rich plant oils used in high concentrations), this may cause a blockage in the pore lining potentially leading to clogged pores and blemishes.