Dear Alice,

I've always wanted a keratin hair straightening/smoothing treatment, but I'm wondering if some of the health risks I've read about are worth the risk. Are some treatments better than others? Is there really an increased risk of cancer?

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?

Does a person's menstrual cycle regulate her bowels in any way? I have had some problems. The week before I get my period, I have loose bowels and the week afterwards I am quite constipated. Is this normal? Is there anything I can do?

I have had Crohn's disease for 16 years and am in remission right now. Recently my boyfriend and I have been toying with the idea of anal sex, but I'm concerned about it given my health issues. I have a lot of thickening of the terminal ileum walls and worry that the "trauma" of anal sex could set off a flare up and be painful because of the narrowing. Any thoughts? I'm way too embarrassed to discuss this with my male doctor. Thanks!

About six months ago, I experienced pain when urinating after having intercourse. Typically, I have pain/burning the first time I urinate after sex, but then the pain tends to go away or diminish. I am a 38-year-old male. I have no pain otherwise.

If a guy has jock itch, can it be passed on to a woman in the form of a yeast infection during sexual intercourse? I had intercourse with a guy and he had jock itch. A few days later I got a vaginal yeast infection. Could there be a connection?

What natural food or herb can help soothe stomach ulcers?

I've been swimming a lot this summer and I have noticed a green tint to my blond hair. Is this caused by previous dyeing? Is it possible to remove the green tint? Thanks for your time.

I have dandruff that responds well to over-the-counter shampoo. Ergo, I have been using the stuff almost exclusively for ten years. No brand in particular, sometimes zinc pyrithione (the blue stuff!), sometimes coal tar (the smelly brown stuff!). Anytime I switch to non-dandruff shampoo for like three to four days straight, I get my dandruff back. I worry that I might be addicted to dandruff shampoo. Should I worry?