Shellfish Allergy - Symptoms and Causes

Overview

• Shellfish Allergy: An immune system overreaction to proteins in shellfish such as crustaceans (shrimp, crabs, lobsters) and mollusks (squid, oysters, scallops).
• Commonality: One of the most common food allergies, particularly affecting adults and more common in women than men.
• Reactions: Range from mild (hives, stuffy nose) to severe (anaphylaxis).

Symptoms

• Begin within minutes to an hour after exposure.
• Includes:
  • Hives
  • Itchy or irritated skin
  • Nasal congestion
  • Swelling (lips, face, tongue, throat)
  • Difficulty breathing (wheezing, coughing, choking)
  • Abdominal pain, nausea, vomiting
  • Dizziness, fainting

Anaphylaxis

• Severe, potentially fatal allergic reaction.
• Symptoms:
  • Swollen throat or tongue, airway constriction
  • Shock, drop in blood pressure, rapid/weak pulse
  • Severe skin rash
  • Nausea, vomiting, diarrhea
  • Dizziness, fainting
• Treatment: Immediate epinephrine injection and emergency room visit.

Causes

• Immune system mistakenly identifies shellfish protein as harmful.
• Response: Production of immunoglobulin E (IgE) antibodies leading to release of chemicals like histamine.

Types of Shellfish

• Crustaceans: Crabs, lobsters, crayfish, shrimp, prawns.
• Mollusks: Squid, octopus, mussels, snails, clams, oysters, abalone, scallops.
• Allergy to crustaceans is more common.

Risk Factors

• Family history of allergies increases risk.
• More prevalent in adults than children; more common in adult women and male children.

Complications

• Anaphylaxis: Increased risk if you have asthma, extreme sensitivity, history of food-induced anaphylaxis, strong family allergy history.
• Treatment: Carry injectable epinephrine (Auvi-Q, EpiPen).

Prevention

• Avoidance: Only way to prevent reactions is to avoid shellfish and related products.
  • Dining Out: Verify no cross-contamination in cooking.
  • Labels: Read carefully for shellfish or cross-contamination.
  • Environment: Avoid places where shellfish is prepared if sensitive to airborne particles.

Special Considerations

• Cross-Reactivity: Shellfish allergy is not related to iodine or radiocontrast dye allergies.
• Preparedness: Wear medical alert jewelry and carry emergency epinephrine.

When to See a Doctor

• Seek emergency treatment for anaphylaxis symptoms.
• Consult a healthcare provider or allergy specialist for symptoms after eating.

For deeper insights, refer to the Mayo Clinic's resource on shellfish allergies. Always consult healthcare providers for personalized advice.