Whenever I have a cold or fever I can’t kick, I always have a long soak in a bath as hot as I can tolerate. I then go under a pile of blankets and sweat for as long as I can. I drink plenty of fluids during this. Always seems to work.
Yep, put good fluids by the bedside and blanket up, suffer the aches and heat until a few hours or the next day you break into a cold sweat.
Once the cold sweat happens you know you beat the flu / cold.
Mind you this does not mean suffer a run away fever of 106 or more, there is a point to go to the hospital or lower the fever.