Bed bugs live off of blood, usually human blood. They also feed on the blood of mice, so make sure you get rid of rodents as well. The feeding itself does not cause pain. Victims may experience an itchy rash or bumps in response to the bites. Some never get any visible bumps. For the most part, negative effects of bed bugs are mental more than physical. They can cause their victims and their households legitimate stress and insomnia. Nonetheless, those itchy bites can’t be ignored either. Bed bugs are not vectors of serious disease. But if you can’t stop scratching the bites, you risk a secondary infection.