Bed bug welts develop after a person has been bitten by a bed bug.
Since bed bugs have piercing mouthparts which penetrate the skin to get to the blood underneath it, the bed bug wound can lead to irritation of the skin.
People cannot feel bed bugs biting because the bed bugs have a natural anesthetic that it injects. This allows the bed bug to feed without interruption. For this reason, the sleeping victim has no indication that a bed bug is feeding.
A mysterious characteristic of bed bug welts is that the reaction will vary from person to person. Some people react by developing huge welts and others develop no welts whatsoever. Some people also react quickly and others take days to react.
The appearance of the welts will vary as well. Some welts look like mosquito bites while others can be large and appear as an allergic skin reaction. When people are bitten for the first time, it is possible that no welts will occur at all. As people get bitten more often, there is a greater chance of antigen development and this is when the welts form. Physicians cannot look at welts and conclusively determine that the irritation is from a bed bug bite. A pattern of three bites in a row, called breakfast, lunch, and dinner might be present, but this is not always the case.
Welts can be itchy, although some people report that they have no sensitivity at all in the affected area. Since welts can take days to appear after being bitten, it is not possible to conclusively determine when bed bug bites occurred. For example, someone who spends five nights in five different places when traveling might incorrectly blame the hotel where they spent the previous night before the welts appeared. That may be the case, but it is also possible that the bites occurred several days prior.
Even people who share the same bed might react differently. Sometimes one person develops welts and the other one does not. It is a matter of debate whether they were both bitten and only one reacted or whether the bed bugs only fed on one person and was not as attracted to the other.
Usually bed bug welts do not require treatment, although itching can break the skin and cause a minor infection. Anti-itch creams may help and if the skin is broken, the wound should be treated with an antibiotic.
Read more about bed bug welts in the Bed Bug Bites section of the site.