I used to colour my hair all the time at the salon and sometimes with home products, no problem. But then I developed a severe allergy with blisters all over my head and a swollen face - very scary! After searching, I found this product and it is wonderful, with a lovely smell. One reviewer talked about needing to rinse for 20 minutes, I'm not sure what they are talking about! You leave the product on for 30 minutes, rinse well, apply the conditioner, leave on for 5 minutes, then rinse again. Easy. It doesn't cover every last strand of grey and washes out after about 6 or 8 shampoos but since it's the only way I can colour my hair, I can live with that! To be super cautious, even though I've used this product many times I still do a 24-hour patch test each time. Better safe than sorry!