How do lice make you itch?

Head lice feed on human blood, and their saliva contains an anticoagulant that prevents the blood from clotting. This anticoagulant also irritates the skin, causing itching. In addition, lice eggs (nits) can also cause itching, especially when they hatch and the nymphs begin to feed.

The main symptoms of head lice are:

* Itching scalp

* Visible lice or nits on the scalp or hair

* Sores on the scalp from scratching

* Difficulty sleeping (due to the itching)