Cutaneous reactions to bedbug bites can vary widely and are easily confused with other conditions (Table 1).15–19 A typical lesion is a 2- to 20-mm, pruritic, erythematous maculopapule with a central hemorrhagic crust or vesicle.5,8 Macules, papules, wheals (Figure 3), vesicles, bullae, and nodules have all been reported,20 as have asymptomatic lesions with a barely visible punctum as the only evidence of a bite.8 Bites vary in number and are preferentially distributed in unclothed areas (e.g., face, neck, extremities). Unlike many other arthropod and insect bites, bedbug bites are rarely located in the popliteal fossae or axillae.21 Lesions can be noticeable immediately when waking up or several days later, with the reaction often progressing from delayed to immediate with subsequent exposures22–26 (Table 2). The classic bedbug rash is referred to as “breakfast, lunch, and dinner” because it commonly presents as several bites in a row or cluster 20 (Figure 4).
The size of bed bug bites varies with a number of different factors. Bed bugs inject an anti-coagulant along with their saliva when they pierce the skin to take a blood meal. This anti-coagulant is mostly responsible for how a person reacts to the bite and determines the size of the bug’s bite. Since people will have various sensitivities to the bed bug’s bite, the size of the bite will vary, as well. Another factor that influences the size of a bed bug reaction is the number of times a person is bitten. Bite reactions of people bitten many times are also variable, and their response may be either more or less intense as the number of bites increases.