This is my post from another thread ..
Test flu is not caused by the flu virus. A rapid spike in testosterone levels especially in the case of using high doses of short estered compounds. They cause the body to treat all of this testosterone, ( or really whatever your using tren ,deca ) in the blood steam as a foreign body. Hence the flu like symptoms. And that in short is why it happens . I dont know any way to avoid it ...
See post # 4...
http://forums.steroid.com/showthread...=test+flu+merc
Merc.