I've used it...it works just fine...I've never had an allergic reaction to it personally but it does itch a little bit while it's on and like the other posters said "stings" a little bit. I've used a couple other drugstore hair bleaches and they are pretty much the same. I liked the last one I got because it came in premeasured packets...I think it was Sally Hansen but just look for the label that says it's premeasured. A bleach cannot make hair come in thicker...must be some old wives tale like the one that says shaving makes hair thinker...this is scientifically impossible.