Fever is not simple overheating. Fever results when something raises the hypothalamic set point, triggering vasoconstriction and shunting of blood from the periphery to decrease heat loss, sometimes with shivering, which increases heat production, and these processes continue until the temperature of the blood bathing the hypothalamus reaches the new set point . Resetting the hypothalamic set point downward, for example with antipyretics, initiates heat loss through sweating and vasodilation.

In fever the set point increases, causing peripheral vasoconstriction and heat conservation, the patient feels cold as blood is shunted to internal organs, and mechanisms of heat production such as shivering help raise body temperature to the new set point.

This is the core problem with the post. Physical cooling works differently from medication: external cooling reduces body temperature by promoting heat loss without affecting the hypothalamic set point . Because the set point is unchanged, the body actively resists the cooling. Even mild hypothermia can elicit a vigorous thermoregulatory defense to maintain body temperature at the hypothalamic set point, and in healthy humans peripheral vasoconstriction is triggered at 36.5°C and shivering at 35.5°C.

UK national guidance is explicit that surface cooling is not a fever treatment: "Tepid sponging is not recommended for the treatment of fever. Children with fever should not be underdressed or over-wrapped." Mayo Clinic's guidance on staying cool is conditional on the absence of shivering: "If you aren't shivering, dress in light clothing, keep the room temperature cool, and sleep with only a sheet or light blanket."

On the size of any internal cooling effect from eating cold things, the best analogous evidence comes from sports science, where large volumes of ice slurry are used: intake of 7.5 to 22.5 g/kg of ice slurry before or during exercise produced a significant core temperature reduction of 0.4°C to 0.7°C, amounts equivalent to 525 to 1575 g for a 70 kg person . That is roughly half a kilogram to over one and a half kilograms of frozen material, consumed by exercising athletes in the heat, not febrile patients, and it produced under one degree of change.

On composition, the post's water figure is correct. USDA data for red or green grapes lists 81 g of water per 100 g , and grape flesh has 75 to 85 percent water content .

On resveratrol, the amounts in edible fruit are orders of magnitude below anything studied for anti-inflammatory effect. Two randomized placebo-controlled trials found that one year of a grape supplement containing 8 mg per day of resveratrol improved inflammatory and atherogenic status in people at cardiovascular risk , and supplements range from under 1 mg to 500 mg per tablet, with no established safe and effective dosage for chronic disease prevention in humans . Dietary intake is far lower: one review estimated intake in the region of 0.2 mg per day, about 5000 times less than the proposed therapeutic dose of 1 g per day, even accounting for additional sources such as grapes or peanuts .

For scale, antipyretic drugs produce reductions on a completely different order. One clinical dataset reported temperature differences between drugs measured in fractions of a degree, with children given ibuprofen averaging 0.18°C to 0.25°C lower temperatures than those given acetaminophen at 1 to 4 hours , while overall drug-induced drops are typically on the order of one to two degrees.