My mother has to blow out my candles sometimes, because they cause her shortness of breath. My husband sneezes with every RED candle I make. It doesn't matter what scent it is, if it's red, he sneezes. My cat is continual contortioned (?) into an upside down stance, itching, biting and scratching despite the fact we have tried every food on the market - sometimes I think it's the candles. My daughter who is an asthmatic - has no problems at all. I do get headaches if I've made several kinds of candles.