bunnyjadwiga

This time, from William Vaughan (1557-1641), Naturall and Artificial Directions for Health (original publication 1600):

Is bathing of the head wholesome?
You shall find it wonderful expedient if you bathe your head four times in the year, and that with hot lye made of ashes. After which you must cause one presently to pour two or three gallons of cold fountain water upon your head. Then let your head be dried with cold towels. Which sudden pouring down of cold water, although it doth mightily terrify you, yet nevertheless it is very good, for thereby the natural heat is stirred within the body, baldness is kept back, and the memory is quickened.

That extreme and cold rinse would definitely be necessary after washing the head with lye, though it would probably kill off any lice, nits, etc. that might be lurking there and probably bleach the hair as well.

Muir also quotes The Widdows Treasure, 1595:

The head anointed with the juice of leeks preserveth the hair from falling. A mouse roasted and given to children to eat remedieth pissing the bed.