Seafood allergy is a topic one should not take for granted. It is one of the most common causes of food allergies affecting an estimated 6.5 million Americans. Oftentimes, seafood allergy is a misnomer for iodine allergy and vice versa.

Mechanism of the reaction

An allergy to seafood occurs when a person becomes hypersensitive to any of the following seafood groups:

• crustaceans
• mollusks
• scaly fish (e.g. cod, salmon, tuna, cod, mackerel)
• cephalopods (e.g. squid, octopus)

Primarily, it is the result of a hypersensitivity of the immune system with the muscle proteins found in seafood. The protein tropomyosin is said to be the major causative allergen for shellfish allergy, while parvalbumin is present in the white muscle of many fish varieties. However, recent studies have also identified a new shrimp allergen called sarcoplasmic calcium-binding protein (SCP). The allergies may be triggered by ingestion, inhalation of fumes during cooking, or even handling of the seafood. The symptoms may include one or more of the following:

• hives and swelling (angioedema)
• tingling and itchy sensation around mouth
• abdominal cramping
• nausea and vomiting
• nasal congestion
• difficulty of breathing
• wheezing (sign of asthma)
• contact dermatitis (rarely, resulting from handling of seafood)

A severe allergic reaction is called anaphylaxis. Manifestations include difficulty of breathing due to swelling of the throat or bronchoconstriction, wheezing, sudden decrease of blood pressure and rapid pulse from vasodilation, dizziness, and loss of consciousness.

What your Doctor can do for you

Some conditions may also mimic the symptoms of seafood allergy following ingestion/handling of the product. Therefore it’s crucial to see the doctor for proper assessment. Patients will be tested for both shellfish and fish allergies. Diagnosis is based on clinical history (including a diet diary) and a few diagnostic tests like prick or patch testing, and RAST. A food challenge may be performed at a physician’s clinic for immediate intervention in case of an adverse reaction. Upon the establishment of the diagnosis, complete avoidance of seafood dishes will be strongly recommended.  A self-injectable epinephrine will also be prescribed. Minor symptoms are alleviated by the intake of oral antihistamines.

What you can do

The major challenge in seafood allergy is the avoidance of the offending agent. Thus, it is very essential to read the labels before you buy or consume anything. Several individuals may experience cross-reactivity between different species of fish and shellfish so it is better to avoid the entire variety or all seafood. Eating out will have greater chances of having an allergy attack because of contamination of utensils and equipment used in food preparation. Consult with your allergist regarding diet modifications. Likewise, involve your family in the treatment plan to make the necessary food adjustments.