How does a blister form from a bedbug bite? - briefly
When a bedbug pierces the skin, its saliva introduces anticoagulants and irritants that provoke an inflammatory reaction, causing fluid to collect between the epidermal layers and form a blister. The blister serves as a protective barrier while immune cells address the offending substances.
How does a blister form from a bedbug bite? - in detail
A bed‑bug bite introduces saliva that contains anticoagulants and anesthetic proteins. The skin’s immune system detects these foreign proteins as threats, triggering a cascade of cellular events.
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Immediate reaction (0–5 minutes).
- Mast cells in the dermis degranulate, releasing histamine, prostaglandins, and leukotrienes.
- Histamine dilates capillaries, increasing vascular permeability and causing localized redness and swelling.
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Fluid accumulation (5–30 minutes).
- Plasma leaks from the permeable capillaries into the interstitial space between the epidermis and dermis.
- The accumulated fluid separates the epidermal layers, creating a clear pocket that appears as a blister.
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Cellular infiltration (30 minutes–2 hours).
- Neutrophils and eosinophils migrate to the site, amplifying inflammation and releasing enzymes that sustain fluid exudation.
- Cytokines such as IL‑1, IL‑6, and TNF‑α further increase vascular leakage.
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Maturation (2 hours–24 hours).
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Resolution (24 hours–several days).
The size and duration of the blister depend on individual sensitivity, bite depth, and the amount of saliva injected. Repeated exposure can heighten the immune response, producing larger or more persistent blisters.