Bedbug bites may cause skin rashes and allergic symptoms, as well as psychological effects. Bedbug bites have a wide range of manifestations on the skin of the host: from no visible effects to big raised blisters. The bite area is commonly accompanied by redness, itching and swelling. There is no treatment for bedbug bites, but steroid cream can be used if itching is severe, as itching may lead to infection.
Bedbugs can be carriers of human diseases such as HIV, but it is unlikely that they can transmit the disease to other humans. There has never been a case of any disease being transmitted via bed bug.