When I was 16, I had an operation which put me in bed for several weeks, during which time I couldn't shower. I remember that my mother sprayed something in my hair that we combed out, enabling me to have somewhat clean hair without taking a shower.
I did a bit of research, and while I didn't find the product any more, I did find something else. Cornstarch. Yup, cornstarch. It's the starch of corn/maize and available in any supermarket. It can also store well in a moisture-proof container. I don't recommend using this all of the time, but this "dry shampoo" will work in a pinch!
What You'll Need:
1/2 cup cornstarch
Take the cornstarch and sprinkle it in your hair. Give it a few minutes to absorb then brush it out. It will absorb the oils in the hair.