As a common ingredient in hair care products, silicone oil (polydimethylsiloxane) is highly favored for its smoothing effect, but the controversy over whether it causes hair loss has never been settled. From the perspective of scientific principles and clinical research, there is a lack of direct evidence that silicone oil causes hair loss, but its potential risks need to be comprehensively evaluated in combination with individual differences and usage habits.
Silicone oil forms a protective film by filling the gaps between hair scales, significantly improving the gloss and smoothness of hair, and is especially suitable for damaged hair. However, its insoluble nature in water may cause some residues to adhere to the scalp, causing two major controversies: one is that the silicone oil film may hinder the normal breathing of the scalp and cause hypoxia in the hair follicles; the other is that the residues combine with oil to clog the pores and induce inflammation. However, it should be made clear that silicone oil has a large molecular weight and is difficult to penetrate the hair follicles, and more than 90% of silicone oil can be washed off in the normal shampooing process, with minimal deposition.
Many studies have shown that the risk of hair follicle blockage is low when silicone oil products are used routinely on healthy scalps. However, for those with oily scalps or those who do not clean their scalps properly, the residual silicone oil mixed with sebum may aggravate the blockage of pores and indirectly lead to atrophy of hair follicles. The main causes of hair loss are still androgenic alopecia, seborrheic dermatitis, malnutrition, etc. Silicone oil may only be a "superimposed factor" rather than a core cause.