Lol, that's what I was saying last night when I commented. Every time I take cold meds they actually make me feel worse the next day. You know those little buggers you are talking about are actually yours...they aren't invaders. Cold and flu viruses aren't what cause the side effects of having colds and flu, they are the cause which your immune system attacks, it's your immune system attacking that causes the side effects. I read that recently and was surprised to find that it's actually your bodies immune response that is usually the leading cause of death. The flu may have started it but the overwhelming immune response some have in fighting it is what actually causes death.

"Much of the systemic symptoms that any of us have with influenza -- the fever, the aches and pains, the sense of exhaustion -- all of those are part of (our body's) response to the virus," said Schaffner. The symptoms we experience are an inflammatory response to the immune system "soldiers" that our body sends to fight any pathogen, he said.

https://www.cnn.com/2018/01/24/health/how-flu-kills/index.html

I don't if that'd be the same as saying one was hit with "friendly fire" but I'd imagine it comes close.