Question: how to use nyda lice treatment?
Answer: Spray all over hair. NYDA should be applied to dry hair. Spray the hair roots thoroughly.
Massage. Massage in until the hair is completely wet. ... 
Comb hair carefully with NYDA's lice comb. After 30 minutes the dead lice and larvae can be combed out with the NYDA® lice comb. ( ... 
Wash with any regular shampoo.