Why do flea bites itch? - briefly
Flea saliva introduces anticoagulant proteins that provoke a histamine release, leading to localized inflammation. The immune reaction to these foreign substances creates the characteristic itching sensation.
Why do flea bites itch? - in detail
Flea saliva contains a complex mixture of proteins, anticoagulants, and enzymes that the insect injects into the skin while feeding. These substances trigger the body’s immediate immune response. Mast cells release histamine, a chemical that dilates blood vessels and stimulates nerve endings, producing the characteristic itching sensation.
The reaction progresses in stages.
- Initial phase (minutes to hours): Histamine release causes redness, swelling, and a sharp pruritic feeling.
- Secondary phase (hours to days): Additional immune cells, such as eosinophils and neutrophils, migrate to the site, prolonging inflammation and intensifying itch.
- Late phase (several days): Persistent exposure to flea antigens may lead to hypersensitivity, resulting in larger, more painful welts and heightened itch intensity.
Individual susceptibility varies. Genetic factors influence the amount of histamine produced, while repeated flea bites can sensitize the immune system, causing stronger responses over time.
Treatment focuses on interrupting the histamine pathway and reducing inflammation. Antihistamines block histamine receptors, providing rapid relief. Topical corticosteroids suppress local immune activity, decreasing swelling and itch. In severe cases, systemic steroids may be required to control extensive hypersensitivity.
Preventive measures eliminate the source of the problem. Regular grooming and the use of veterinary‑approved flea control products reduce flea populations, thereby decreasing the frequency of bites and the associated pruritic reactions.