Do head lice cause harm?
Head lice rarely (if ever) cause direct harm, and they are not known to transmit infectious agents. Thus, they should not be considered as a medical or a public health problem. These lice may occasionally be burdensome because of annoyance; their presence may cause itching and loss of sleep. The greatest harm associated with head lice results from the well-intentioned but misguided use of caustic or toxic substances to eliminate the lice.
