<prompt> Untoff phenomenon isWorsening of symptom with coldRelief of symptom with coldWorsening of symptom with heat and exeionPalsy of symptom with heat and excretion  <response>: Harrisons principles of internal medicine 17th edition. Ul visual blurring may occur following a hot shower or with physical exercise. Uhthoffs phenomenon also known as Uhthoffs syndrome, Uhthoffs sign, and Uhthoffs symptom is the worsening of neurologic symptoms in multiple sclerosis MS and other neurological, demyelinating conditions when the body gets overheated from hot weather, exercise, fever, or saunas and hot tubs. Ref Harrison20th edition pg 2345 