Yeah, if you're delirious from a flu (assuming you mean the fever), you need to go to either your primary care physician or the ER. Do not try to "sweat it out."
The ER will be more than happy to have you there even if you could have stayed home. They know what they're doing; they're not going to let someone else die to treat your sniffles.
...and an IV drip usually doesn't help that much, and its not good to have too many of those.
Even if you have a healthy immune system, if you're delirious from a fever, you should call your doctor ASAP.
Note: I'm not a doctor, this is not medical advice, yadda yadda. I've just been living with Crohn's disease long enough to learn some of this from my own visits to the ER.
But really, why do you think flu is so deadly? If you are very young, very old, or have other medical conditions, fine, it makes sense to hit the ER. If you are a healthy adult and just got hit with a bad one/two day flu, you are able to keep your fluids in (beyond sweating them out), you don't need to hit the ER even if you feel like crap... By delirious, I'm talking about shady gradients anyways, I've never had more than sweating dreams where nothing makes sense. Ya, there is a point where you should go the ER, but our thresholds are fairly diverse.
[0]: http://www.cdc.gov/flu/about/disease/us_flu-related_deaths.h...
[1]: http://en.wikipedia.org/wiki/Delirium
[2]: http://www.insweb.com/health-insurance/5-common-flu-season-h...