I dyed my hair every 3 months all through my 30's using Naturtint, never had any problems with it. Then just over a year ago, when I had just turned 40, I used it again after a long time of not using it, the patch test that you are supposed to do first was okay. Later on that day I did notice a slight burning sensation in my scalp, nothing really bad, and my hands were really irritated and swollen from where I had handled the dye (washed it out without using the gloves). This went away after a day. Since then I have been terrified to dye my hair, in case I have become allergic to hair dye. I bought another one Olia by Garnier and did a patch test on my arm 3 days ago, after 1 day no redness or itching or any visible irritation to the skin, on the second day I have some kind of nerve pain in my arm, around where I applied it, but still no visible irritation to the skin. It is kind of like a burning sensation. I have also not really been feeling well. Today - this is over 72 hours after doing the patch test, I still have the nerve pain, still don't feel well, and no visible irritation to the skin though. I have had 2 showers, so it's definitely washed off. The amount I used on my arm was about the size of a 10p coin, maybe smaller. Obviously I'm not going to use it on my hair, and the thought makes me shudder, if I'm in this much pain where I did my patch test. The thought of an allergic reaction to a hair dye scares me more than anything in the world as I have seen photos of what happens and read about the symptoms. I have no intention of using the dye, but now I'm scared that I'm going to be seriously ill from just the patch test as there is still pain.