Why do mosquito bites itch? The science and how to stop it

Mosquito bites itch because the immune system reacts to proteins in mosquito saliva, not to the bite itself. When female mosquitoes—males don’t bite—inject saliva during feeding, the body recognizes more than 100 saliva proteins as foreign and triggers an immune response. Mast cells release histamine, which dilates blood vessels to form the red bump and activates skin nerve endings that produce the itch. The article also notes that scratching can damage the skin barrier and prolong healing, increasing infection risk. For relief, it highlights cold compresses, antihistamines, and hydrocortisone cream, while prevention relies on DEET, picaridin, or oil of lemon eucalyptus.