Head lice are nasty, can cause itchiness and are very contagious, but the pesticide based shampoo sold to get rid of lice are even worse. Pesticide based lice shampoo has been known to cause seizures, mental retardation, many different allergies and respiratory problems, strange tingling, burning, itching, attention deficit disorders, brain tumors, leukemia, cancer and death. All Natural enzyme based lice shampoo gets the job done without the danger.