The Claim
"Hot water opens your pores and cold water closes them."
The Science
Pores are not muscles. They do not have the ability to open and close on command. This myth has persisted for decades, often repeated by beauty professionals and even some dermatologists, but it has no basis in skin physiology.
What hot water and steam actually do is soften the sebum and debris trapped inside pores, making it easier to extract during cleansing. This gives the appearance of 'opening' pores, but the physical structure of the pore itself does not change. Similarly, cold water can temporarily cause slight constriction of the skin around pores, making them appear smaller, but this effect is temporary and superficial.
Pore size is primarily determined by genetics and skin type. Oily skin tends to have larger, more visible pores because sebaceous glands produce more oil, stretching the pore opening over time. The most effective ways to minimize pore appearance are regular use of BHAs like salicylic acid, retinoids, and niacinamide — not water temperature.
Key Takeaway
Pores are not muscles and cannot open or close. Hot water can soften debris inside pores making cleansing more effective but it does not change pore size.
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