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?

The Internet has lots of false facts on it. I want to know if I should consider all the health/drug/sex/emotional stuff as fact in science/doctor advice, and what areas are not so qualified in knowing. The reason being is I want to be more informed, and I don't like to be mistaken in passing along knowledge that I don't know to be credible or not.

1) I'm considering getting my tongue pierced. Is there anything I ought to know before I get it done? What should I look for in a piercing place? Does the piercing ever have negative effects — I don't know, tongue paralysis or something? Thanks!

2) If and when I decide to take my tongue ring out, I worry that there will be scarring tissue or an ugly hole in the middle of my tongue. Is this the case?

I am young, and I'm switching gynecologists, but I am worried about having a male one. I had a female before and I wasn't as uncomfortable about going. Is there any reason I should be worried?

Is there a service I can employ? I know for a fact that I've never used health insurance to cover anything. I also know that I've been to different hospitals for different issues. Any help is appreciated.

I am transgender, female to male. I have been on hormones for 8 years now, and have gone through pretty much everything except GRS. I haven't gone to the gyno for a few years. I was wondering if I should still get checkups or not?

1) I often have a bad taste in my mouth, and bad breath as well, I assume. This doesn't stem from poor hygiene: I brush my teeth at least three times a day, and usually more. I'm wondering if there is anything I can do about this. Could this be a symptom of some sort of nutritional deficiency? I think my diet is pretty bad, although I'm working pretty hard on getting more protein and eating less fat. I've also been nauseous a lot lately, and vomiting some. Could that be related?

2) Like many people, I often have an embarrassing bad breath. Listerine and other mouthwashes won't be of any help for this chronic problem. There are lots of products available to get rid of "volatile sulfur compounds (VSC)" - that supposedly cause this — and I just don't know which one I should try. Also, what's your opinion on tongue-brushing?

1) Which is better for you, tap or bottled water?

2) How bad is the water here in New York City? Do you recommend drinking filtered water, or does it really make a difference?