This IgE antibody allergy test uses a blood sample to determine if you are allergic to Crab, a common shellfish. A crab allergy is usually related to a crustacean or shellfish allergy. Crustaceans include shrimp, lobster, crayfish, prawn, and crab. Crab allergies are fairly common, however, it’s also one of the most serious causes of anaphylaxis, on par with a peanut allergy. Anaphylaxis can be life-threatening and is considered a medical emergency. If you notice any of the following symptoms, you may be experiencing anaphylaxis: LightheadednessDizzinessA drop in blood pressureDifficulty breathingSwollen throatLess severe crab allergies may cause a different set of symptoms which can take anywhere from a few minutes to a few hours to develop. If you experience any of the following symptoms, you may be experiencing a less severe (but still concerning) allergic reaction to crab: CongestionDifficulty breathingDiarrheaNausea/vomitingItchiness or HivesIf you are allergic to crab, it’s because your body is mistakenly identifying a protein in the crab as a threat to your body, and your body releases antibodies to the protein. If you continue to eat crab, your body will release chemicals and histamines to fight the crab protein, causing an allergic reaction. You are more likely to have a crab allergy if shellfish allergies are common in your family. Adult women are at highest risk for developing a crab allergy. You are more likely to have a severe allergic reaction to crab including anaphylaxis if you have asthma. Crab is also considered an occupational allergy and can affect seafood industry workers and those who come into contact with water that was used to boil and cook crab.