Do you use this to touch up your grey roots monthly?

Grecian Formula will gradually restore color to your hair. It is not a root touch-up product or a hair dye. You would use it daily until you get your desired results and then use it once to twice a week to maintain those results.

Has the Grecian Formula changed?

Grecian Formula changed from their orig formula in 2017, dropped the lead acetate. Grecian Formula no longer is the least bit effective.!

Does the color have expiration date?

The bottle does not have an expiration date. The color fades with time. You apply the formula every day and when you get to the darkness you like, you stop and only a plan about once a week.

I have colored my hair at home. can i use grecian formula or do i have to wait?

You can use it now. Just know that the new (non lead acetate containing) formula is very, very gradual. You will likely need to use it consistently for some time to notice a lot of difference. Also, I take it from your name you are a woman. If so, and you have long hair, I cannot recommend it since the chemical can really get in your eye sometimes and the longer your hair is, the more I would think this would be likely.