Why is it that when a person vomits, it causes others to vomit — even when they don't have an illness causing it? Is this something triggered by the brain or is it something that happens by reflex (survival instinct) for someone to vomit since, perhaps, what the first person was eating may affect the second who vomits as well?

I have a frying pan from which the Teflon coating is beginning to flake off. Last night I was cooking a dish involving a white sauce when I noticed what could only have been flakes of Teflon in the sauce. I threw the meal out, as I had a roommate tell me one time that Teflon is poisonous; but flaky Teflon frying pans seem pretty common. I couldn't find anything on the web to say that Teflon was bad for you in that form. Are there any health risks that go with eating from pans where the Teflon is coming off?

I was hoping you could answer a question for me about birth control pills. There is a history of breast cancer in my family (my mother). Is it true that because of this, it is unsafe for me to use birth control pills? A few friends have recently had condoms break during sex, and I am looking for a type of "backup" contraception system.

I'm HIV positive, very low viral load & great t-cell count (not on meds). I've been reading recently that flu shots aren't all they're cracked up to be. What are the dangers of a flu shot, and if my immune system is already doing well, should I still get a flu shot?