Symptoms of a shellfish allergy usually develop within minutes of eating shellfish. They may range from mild to life-threatening. When compared with other food allergies, shellfish allergy reactions tend to be severe.
Many of the symptoms of a shellfish allergy affect the skin, including itchiness, skin rashes, hives, or eczema. The skin may also swell or tingle, particularly that of the lips, mouth, and any other area that has come in contact with the seafood. This swelling is known as angioedema. Eating shellfish may also cause itchy, red, or watery eyes.
Shellfish allergies also commonly cause gastrointestinal or digestive issues, including nausea, vomiting, abdominal pain, bloating, and diarrhea. Many people with a mild shellfish allergy find that these are the only symptoms they experience after consuming shellfish. Allergic reactions to shellfish also commonly affect the person’s ability to breath, including swelling of the tongue and throat, blocking the airways. Other reactions including nasal congestion, wheezing, and asthma-like symptoms.
A severe allergic reaction, known as anaphylaxis, can be fatal if not treated promptly. This reaction requires treatment with epinephrine (usually administered through an Epi-Pen auto injector) and a trip to the emergency room. Signs of anaphylaxis include airway constriction causing breathing difficulties, rapid pulse, lightheadedness or loss of consciousness, and a severe drop in blood pressure. As a result of this reaction, the person will go into shock, and may die if emergency medical care is not received. For some people, even contact with trace amounts of shellfish can cause these symptoms.