Fleas are blood-feeding insects. Pain and itching results from an allergic reaction to the materials that the fleas inject into the skin at the time of the bite.
Review Date 10/16/2017
Updated by: Jesse Borke, MD, FACEP, FAAEM, Attending Physician at FDR Medical Services/Millard Fillmore Suburban Hospital, Buffalo, NY. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.