Shellfish Allergy

Shellfish allergies can be challenging to diagnose. Symptoms differ from person to person, and the same person can have different reactions after eating shellfish. You may have a reaction without even eating shellfish — for example, if you’re cooking it or shellfish contaminates your food.

To diagnose a shellfish allergy, your healthcare provider or allergist will ask you about your symptoms. You may need to answer:

• What did you eat? And how much?
• When did symptoms develop?
• What symptoms did you have?
• How long did symptoms last?

Will I need food allergy testing to diagnose a shellfish allergy?

After asking you about your symptom history, your provider may do food allergy testing to confirm a diagnosis:

• Skin prick test: During this in-office test, your provider places a drop of the allergen on your skin and pricks your skin. The drop seeps into your skin. Your provider will confirm a diagnosis if a red, itchy bump appears after 15 to 20 minutes.
• Blood test: A blood test can help detect whether you have food allergy antibodies but doesn’t diagnose a food allergy.

These tests aren’t conclusive. Together with your symptoms and history, your provider will make a diagnosis.

Will I need an oral food challenge?

Oral food challenges can provide a definitive diagnosis. Under strict, careful supervision, you eat a small amount of the allergen. Your provider increases the dose gradually and notes your symptoms. Occasionally, allergists can use this test to see if you’ve outgrown the allergy. However, most people don’t outgrow shellfish allergies.