How do bedbugs bite, causing itching? - briefly
Bedbugs insert a slender proboscis into the skin, delivering saliva that contains anesthetic and anticoagulant agents. The immune reaction to these proteins produces red, raised lesions that itch intensely.
How do bedbugs bite, causing itching? - in detail
Bed bugs feed by inserting a specialized proboscis through the skin. The mouthpart consists of a fascicle of slender stylets that pierce the epidermis and reach the superficial dermal capillaries. Once the blood vessel is accessed, the insect injects a small volume of saliva that contains anticoagulants, vasodilators and anesthetic compounds. The anticoagulants prevent clotting, allowing continuous blood flow; the vasodilators expand the vessel, and the anesthetic reduces immediate pain, so the bite often goes unnoticed at the moment of feeding.
After the blood meal, the host’s immune system reacts to the foreign proteins in the saliva. Histamine and other inflammatory mediators are released, producing:
- Redness around the puncture site
- Swelling that may enlarge over several hours
- A pruritic (itchy) sensation that peaks 12–24 hours after the bite
The intensity of itching varies with individual sensitivity, the amount of saliva injected, and the number of bites received. Repeated exposure can sensitize the skin, leading to larger wheals and more pronounced discomfort.
The itching itself originates from histamine binding to receptors on sensory nerve endings in the epidermis. This activation transmits signals to the brain, interpreted as a desire to scratch. Scratching disrupts the skin barrier, potentially introducing secondary bacterial infection and prolonging inflammation.
Key factors influencing the reaction:
- Host allergy level – individuals with heightened immune responses develop larger, more itchy lesions.
- Quantity of saliva – larger blood meals introduce more allergenic proteins.
- Number of bites – clustered feeding sites amplify the local inflammatory response.
Management of the itch includes topical antihistamines, corticosteroid creams, or oral antihistamines to block histamine receptors, reducing redness and relieving discomfort. Keeping the skin clean and avoiding scratching helps prevent secondary infection.