Neem extracts have hormone mimics that interfere with the life cycle of parasites, inhibit their ability to feed and prevent the eggs from hatching. Lice are usually treated with shampoos incorporating neem extracts followed by applying a neem-based cream to the hair and scalp. This is left overnight and washed out in the morning. Before washing (with a neem-based shampoo), use a flea comb to remove the dead lice and sterile eggs.