If a person body does not accept shrimp as food instead it thinks it as toxic substance and secrets the antibodies against the toxic (here it refers to shrimp). It results in the symptoms such as itching, irritation, scaling, skin scraping, nausea, diarrhea or vomiting, Swelling of neck and thickening of tongue. Early days the test was like pricking the allergic material into the body and tested for reaction. But now, drawing out some blood sample from a person and external testing of injecting allergic material to it and checking for reaction of blood to the allergic substance is followed.