Lice eggs (nits) stick to the hair and can be hard to remove. After treatment, some nits may survive. You don't have to remove all of the nits. But some people use a comb to remove nits after using lice medicine, because they don't like the look of nits in the hair.
After you rinse the medicine from your hair, you can use a fine-toothed comb to remove nits. The combs are often packaged with over-the-counter lice shampoos. A flea comb that's made for dogs and cats will also work.