Hair Coloring Agents

Dear Dr. Rassman,
I am a 56 year old man and I started having grey hair when I was about 20. I have a full head of hair and little or no receeding. I have tried hair coloring like Just for Men and it burns my scalp and gives me terrible rashes for days. I have tried the Grecian Formula type of treatment with varying degrees of success, but it seems to yellow my hair and I am also concerned whether it is safe or not- I believe it contains lead? Finally, I think (or possibly I am imagining) that I am seeing very slow improvement with Melancor. Is this product safe?

Any advice that you could give me about Melancor and also the Grecian formula type hair treatments would be greatly appreciated.

I am a doctor, not a hair stylist. The answer to your questions would best be obtained from people who use or recommend the products. I have no way to tell you about the safety or ingredients. I did try to look it up, but there are only slanted views available in the public domain. Sorry.