On a personal note…
Myself and my daughter have had a cold with flu symptoms recently, one thing we noticed, taking herbs and using essential oils did not seem to interfere with the course of the flu, we still ran a fever day 2 or 3 and over the course of 1 night that fever broke and we began to feel better. With herbs and essential oils we were able to rebuild our energy and immune system making for a minimal amount of sick time.
With over-the-counter things we might have taken, they lower the temperature so your body does not run the course of the flu naturally thus possibly increasing the length of illness.
Just a personal observation not sure how much science there is behind it. I welcome input, drop us an email or give personal input on facebook.