Shellfish allergies are the most common adult-onset food allergies.
Shellfish allergy is an reaction by the body's immune system to proteins in certain marine animals. Such as shrimp, crabs, lobster, squid, oysters, snails.
if you have shellfish allergy, the only way to avoid an allergic reaction is to avoid all shellfish and products that contain shellfish.
Diagnosis: Clinical examination,history is very important. Skin prick test, Blood test,IgE test.
Few homoeopathic medicines which can help in this cases are as colch, graph, phos, zinc,nat mur. Though you need proper constitutional treatment for it .