Is gentian violet safe to use as an alternative hair dye? pros and cons? possibility of reaction?

Gentian violet: I am not familiar with the use of Gentian violet as a hair dye. It is commonly used as an antiseptic. Test a small amount on your skin first to see if you are sensitive to it - redness, swelling, pus are signs of an allergic reaction or infection. Avoid placing on scalp at site of any open wounds. Better to use plant based hair dyes (no ammonia), generally considered safe.

Safe not practical: Gentian violet is commonly used in the mouths of small children, so it should certainly be safe on the scalp. However it stains everything it touches, so there are far more practical options for hair dyeing.