Instruct: Classify a given review as either positive or negative.
Query: I'll never use pro heath again!!!!

After using the whitening version of this product for two weeks by cheeks and inside of lower lip became red and rough. The next day white "canker sore" eruptions occurred throughout my mouth. I have never had more than one canker sore in my mouth at a time in my life. My dentist said it could have been an a reaction to a new toothpaste, and bingo, I knew it was this stuff. HORRIBLE! I haven't been able to eat anything more than vanilla ice cream, milk, and white bread for 4 days now. The pain is horrible and unrelenting. No over the counter remedies are helping, and I've purchased them all. Similar reports are all over the internet. Be careful!!!!