If you can get something called "Shampoo Color" I'd go for that. It washes out pretty soon. I used to buy it in England, as you can't get it in Denmark. However, I saw two different brands of it in a bottle in California. I bought the wrong one, it didn't have any effect what so ever! I'll ask ES for the name of the shop.

I have a friend who is naturally blonde, still, she uses lemon juice to keep it highlighted.

I'd like mine a little darker, and I wonder if strong tea would have any effect. LOL!