Applied Evidence

When bed bugs bite

Mark K. Huntington, MD, PhD
Sioux Falls Family Medicine Residency Program; Department of Family Medicine, University of South Dakota Sanford School of Medicine, Vermillion, SD

The author reported no potential conflicts of interest relevant to this article.

Treating bed bug bites is straightforward; helping patients control and even prevent future infestations is another matter. Here’s how you can help.



Provide symptomatic relief for bed bug bites with antihistamines or corticosteroids. C

Advise patients experiencing an infestation to consider the CDC’s recommended integrated pest management program (eg, heat treatment, vacuuming, nonchemical pesticides) to increase the likelihood of successful extermination. C

Strength of recommendation (SOR)

A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series

Bed bugs, Cimex spp, are a re-emerging public health problem in the United States. First recorded by the ancient Greeks,1 bed bugs have plagued societies for centuries. In the United States, infestations peaked in intensity in the 1920s and 1930s, then were largely eliminated as a significant concern after World War II, thanks to synthetic, residual pesticides.2 By the mid-1990s, bed bugs were so uncommon that specimens could not be obtained for medical education purposes.3

That has all changed.

Although commonly perceived as disproportionately affecting the underprivileged,4 bed bugs are equal-opportunity pests, infesting the most posh hotels, retailers, and theaters.5,6 According to one news report summarizing data from a national pest control firm, US cities with the highest infestation rates are, in descending order: Cincinnati, Columbus, Chicago, Denver, Detroit, Washington DC, New York, Philadelphia, Dayton, and Baltimore.7 Although bed bugs are not known to transmit infectious diseases, they are responsible for significant dermatitis, allergic reactions, and psychological distress.

Bed bug biology and behavior

The bed bug life cycle has 7 stages. All but the egg stage require blood meals before the arthropod can molt to the next stage. Bed bugs are attracted to their hosts by body heat and exhaled carbon dioxide, and they feed only through the skin. This makes baiting and trapping challenging, although it’s a common extermination strategy for other domestic pests. Also, unlike cockroaches, flies, or other pests, bed bug infestations are not associated with hygienic deficiencies. Improved housekeeping does not significantly affect their populations; bed bugs feed on household inhabitants, not their spilled or improperly stored food. However, clutter does increase their chances of finding refuge.

Interestingly, researchers recently discovered that bed bugs are themselves hosts to the endosymbiotic bacterium, Wolbachia.8,9 This genus is found in many invertebrates and appears to be essential for normal bed bug fertility and reproduction. Targeting the bacteria may inhibit the ability of bed bugs to breed—something we’ll discuss a bit later.

Clinical assessment

Patients with bed bug bites complain about intensely pruritic lesions. These are typically erythematous and indurated and may be hemorrhagic. The pattern of bites is often linear, and 3 bites in a row are common, sometimes referred to as “breakfast, lunch, and dinner.” Patients typically have no recollection of being bitten, as bed bugs feed on sleeping hosts, and their bite is usually painless.

Clues to bed bugs as the source. Scabies mites also cause linear pruritic lesions, but bed bug lesions differ in appearance and distribution. Scabies lesions are subtle, appearing as burrows and excoriations, in contrast to the more prominent erythematous papule seen with bed bugs and other arthropod bites. Scabies tend to occur in skin folds, finger webbing, genitals, and areas where clothing is tight, such as beltlines. In contrast, bed bugs tend to attack easily accessible, exposed areas. Areas covered with loose clothing are less affected, and areas covered by tight clothing are essentially spared. Multiple members of the household are often affected.

Flea bite? Bed bug bites may be virtually indistinguishable from those of other arthropods such as fleas, spiders, or mosquitoes. While the linear 3-bite pattern may suggest bed bug exposure, it is not pathognomonic. Capturing the arthropod or finding evidence of infestation (discussed in a bit) is needed to confirm a bed bug as the source of the bite.

The etiology of pruritic papules is broad. Besides arthropod bites, include conditions such as papular eczema, papular pruritic eruption, and eosinophilic folliculitis in the differential diagnosis.

Potential for complications
As with any break in the skin, secondary infection is a risk, although it is rarely a complication of the bite. If infection occurs, it is more likely due to scratching. Bed bug bites are allergenic, and they have also been implicated in asthma exacerbations and even anaphylaxis.10,11 In severe infestations, anemia from the extensive blood-meals can occur.12

Experimental studies have found that >45 human pathogens—ranging from viruses to methicillin-resistant Staphylococcus aureus to helminths—can survive ingestion by bed bugs, but none have shown pathogens to be transmitted to humans by bed bugs.11 Fortunately, bed bugs do not appear to be competent as vectors, although prospective studies are ongoing.13 In addition to allergic manifestations, bed bug bites have been associated with significant, even incapacitating, psychiatric problems such as anxiety, obsession, and depression to the point of suicide.14