NYDA should be applied to dry hair and Spray the hair roots thoroughly with NYDA
Massage NYDA in until the hair is completely wet and allow it to take effect for 45 minutes.
After 45 minutes, the dead lice and larvae can be combed out. However, you should not wash the hair yet because NYDA should work longer on the scalp.
NYDA should act for a total of at least eight hours or overnight. Use any regular shampoo to wash the hair after treatment with NYDA.