Cockroaches secrete an oily liquid that has an offensive and sickening odor. This odor may also be imparted to dishes that are apparently clean, food and clothes. Excrement in the form of pellets or an ink-like liquid also contributes to this nauseating odor. Additionally, cockroaches produce allergens, which include their feces, shed skins, and body parts such as antennae and legs. In susceptible individuals, contact with these allergens can result in mild to severe rashes, other allergic reactions, and in extreme cases death from asthma attacks.

Not only do cockroaches eat (and excrete on) our paper products, boxes, and food, but through spreading their filth and contaminating our food and environment with a variety of human pathogens, cohabitating with cockroaches can be detrimental to human health. Many asthmatics, as well as many others, develop allergic sensitivities to the presence of cockroaches, and cockroaches will elicit far more potent reactions from most asthmatics than other substances to which they are sensitive. Cockroaches are vectors of bacteria, fungi, and viruses. In addition to spreading Salmonella, which causes food poisoning, they also carry Streptococcus, Staphylococcus, Clostridium, and Coliform bacteria, the tubercle bacillus, and other bacteria and pathogens which may cause abscesses, boils, Bubonic plague, diarrhea, dysentery, gastroenteritis, intestinal infections, leprosy, lesions, Typhoid fever, and urinary tract infections.

Cockroaches affect more people than any other insect. They vomit partly-digested food materials and continually defecate while eating and pose significant health hazards by transmitting diseases (bacillary dysentery, typhoid fever, cholera, polio, amoebic dysentery, urinary-tract infections, diarrhea, and infectious hepatitis). The debris created by cast-off cockroach skins, dead bodies and droppings can aggravate allergies, especially in children and sensitive individuals.