Cimicosis is a skin condition caused by bedbug bites. Depending on individual sensitivity, bites can cause a raised red bump or flat welt, sometimes accompanied by very intense itching caused by an allergic reaction to the anesthetic in the bedbug’s saliva.Reactions to bedbug bites may look like mosquito bites, though they tend to last longer.Bites may not be visible and can take up to nine days to appear.Bedbug bites tend not to have a red dot in the center as is characteristic of flea bites.As with flea bites, bedbug bites are sometimes sequential, often in rows of three.

A typical bedbug bite
Individual responses vary greatly. In about 50% of cases, there is no visible sign of bites, and for those who do have a visible sign, it varies in size and itchiness, greatly increasing the difficulty of identifying and eradicating infestations. This means that itchy welts cannot be used as the only indicator, and that initial infestation can be asymptomatic and go undetected.
Serious bed bug infestations and chronic attacks can cause anxiety, stress, and insomnia. Development of refractory delusional parasitosis is possible, as victims develop an overwhelming obsession with bedbugs.

A bedbug nymph feeding on host
Patients given systemic corticosteroids and antihistamines for the itching associated with bites will still have visible signs of bites. Topical corticosteroids, such as hydrocortisone, can reduce lesions and decrease itching.
The application of hot water may relieve symptoms. The water temperature should be about 50 °C (120 °F), or this procedure may aggravate the symptoms. Disagreement exists as to why heat causes symptoms to abate. Heat might overwhelm the nerve endings that signal itch; it might neutralize the chemical causing inflammation, or it might trigger a large release of histamine, causing a temporary histamine deficit in the area. Another theory is that the heat denatures the proteins in the bedbug saliva, changing their composition enough so that they no longer trigger the body’s defensive mechanisms.

Disease transmission
Bed bugs would seem to have all the prerequisites for passing diseases from one host to another, and at least twenty-seven known pathogens (some estimates are as high as forty-one) are capable of living inside a bed bug or on its mouthparts, yet there are no known cases of such transmission. Extensive laboratory testing indicates that bed bugs are unlikely to pass disease from one person to another.

Other effects on health
The salivary fluid injected by bed bugs can cause skin to become irritated and inflamed, although individuals can differ in their sensitivity. A few cases of bullous eruptions have been reported Anaphylactoid reactions from the injection of serum and other nonspecific proteins are observed and the saliva of the bedbugs may cause anaphylactic shock, though rarely. In rare cases of intense and neglected infestation, sustained feeding by bedbugs may lead to anemia. Secondary bacterial infection (i.e., infections from scratching itchy skin too much) are possible.
Systemic poisoning may occur if the bites are numerous.
The World Health Organization reported in 2008 that bedbugs may cause bronchial asthma through the release of airborne allergens and that numerous bedbug bites may cause victims to become more susceptible to other diseases, as well as causing “general malaise”.