Ice wins this contest. As cubes crack against coffee, their cold surface strips heat from the drink and from your mouth, while dilution softens the sharp edge that a hot, concentrated cup can leave behind. You register refreshment before flavor has time to make a case. That is the trick. It is sensation first, coffee second.
Hot drinks can overperform. Heat drives volatile aroma compounds into the air, making a layered drink smell rich while also letting roast notes, sweetness, spices, and dairy pile up at once. Iced coffee runs leaner. Cold suppresses volatility, so fewer aromas crowd the nose; at the same time, TRPM8 receptors signal cooling across the mouth. At higher temperatures, retronasal olfaction keeps delivering flavor after each swallow. You do not merely taste chill. Your nervous system reads it as relief.
Milk is not decoration. Its fat and casein can mute bitterness and astringency, while a modest pour makes the liquid smoother without the bulk of foam, syrups, or spice. The caffeine may be unchanged. The effect is largely perceptual, not a special hydration bonus: cooler temperature, gentler aroma, and less sensory clutter leave you feeling reset. That small gap matters. So when you reach for the plain iced version, are you choosing less coffee, or simply giving your senses less to fight?