If you have a shellfish allergy, you may need to avoid all types of shellfish due to uncomfortable and potentially life-threatening symptoms. The good news is that a shellfish allergy is very manageable. By avoiding shellfish and taking some precautions, you can enjoy an active, healthy life.
A shellfish allergy is a type of food allergy. Shellfish are animals that live in the water and have a shell-like exterior. There are two types of shellfish:
If you have a shellfish allergy, don’t eat these ingredients and foods:
Often, if you have an allergy to one type of shellfish, you’ll have an allergy to other types. Crustaceans cause more allergic reactions than mollusks. But, just because you react one way to one type of shellfish doesn’t mean you’ll react the same way to every single type.
You might have a reaction after eating lobster, for example, but eat scallops without a problem. If you have symptoms after eating shellfish, talk with your healthcare provider before eating any other type of shellfish.
An allergist can figure out if you’re allergic to shellfish or have an intolerance. The difference matters. While a food intolerance causes uncomfortable symptoms that mainly affect your stomach or digestive system, an allergy can affect your entire body and be life-threatening.
Anyone can develop a shellfish allergy — even if you’ve had shellfish before without any problems. Although it can occur at any age, it appears more often in adults than in children. About 60% of people who have a shellfish allergy first get symptoms as an adult. The reason may be that children typically don’t eat shellfish. People often eat shellfish for the first time as adults, which may be why symptoms appear later in life.
Approximately 2% of the U.S. population (around 6 million people) has a shellfish allergy.
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Shellfish allergy symptoms range from mild to severe. One person may experience itching and hives while another could have a life-threatening reaction, such as breathing problems. Symptoms can affect many different parts of your body like your skin, lungs, digestive system and heart.
Shellfish allergy symptoms include:
Typically, allergic reactions to food occur soon after eating the food — within a few minutes to a few hours.
A shellfish allergy, or any food allergy, results from an immune system overreaction. Your immune system defends your body from invaders, such as infections. A food allergy occurs when your body identifies a food substance as a foreign invader and attacks it.
The most life-threatening complication of a shellfish allergy is anaphylactic shock, a severe type of allergic reaction. Allergic reactions are hard to predict. Even if you experience a mild reaction the first time, the second allergic reaction could be severe. That’s why it’s important to let your healthcare provider know if you have allergic reactions to any type of food. Your safest bet is to catch an allergy before it surprises you with a life-threatening reaction.
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:
After asking you about your symptom history, your provider may do food allergy testing to confirm a diagnosis:
These tests aren’t conclusive. Together with your symptoms and history, your provider will make a diagnosis.
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.
You can’t become “un-allergic” to shellfish. The best way to keep yourself healthy is to avoid shellfish. Besides avoiding shellfish itself, make sure you avoid foods that contain shellfish.
The Food and Drug Administration (FDA) requires food manufacturers to list common food allergens, such as shellfish, on food labels. The food label lists the allergen either in the ingredients list or after the list. For example, if a product contains abalone, a species of shellfish, the label will state “abalone (shellfish)” in the ingredients or “contains shellfish” after the ingredients list.
Epinephrine is the main treatment for anaphylaxis. Once your provider has confirmed a shellfish allergy, you’ll get a prescription for self-injectable epinephrine (EpiPen®). Your provider will teach you how to use it.
If you have a severe allergic reaction and inject yourself with epinephrine, the next step is to call 911. Make sure to tell the dispatcher what happened and that you used your epinephrine injection. Emergency medical technicians (EMTs) may need to give you another dose when they arrive.
Use the injection right away if you notice:
If you’re not sure if you need to use the injection, most allergists recommend using it. The benefits of using it outweigh the risks of using it when you don’t necessarily need it.
If you have mild symptoms, your healthcare provider may recommend an antihistamine. However, only epinephrine can treat the severe symptoms of anaphylaxis.
Yes, Benadryl® and other antihistamines can help with mild allergic reactions like itching skin or skin rash.
The only way to avoid the negative effects of shellfish is to avoid shellfish entirely.
In addition to not eating shellfish, these precautions can help you stay safe:
These food items may contain shellfish, as well, so avoid eating them:
Any food allergy can be dangerous. Even if you’ve only experienced mild allergic symptoms to a food, you can always potentially have a dangerous reaction to that same food. It’s smart to be careful and prepared. Always carry your epinephrine injection with you. Note the expiration date so you can get a new one before it expires.
Most people who have a shellfish allergy have it for life. It doesn’t go away over time.
You can live a healthy, enjoyable, active life with a shellfish allergy. Take some precautions to keep yourself healthy and feeling your best:
Contact your healthcare provider if you notice any allergy symptoms after consuming shellfish. Even if your first reaction was mild, your second or third reaction could be severe. It’s best to be safe and have your provider test you for a shellfish allergy.
Go to your nearest emergency department if you have symptoms of anaphylaxis (like difficulty breathing and/or difficulty swallowing), or if you don’t get relief from using your injectable epinephrine.
It’s normal to have questions about shellfish allergies. Some questions you may want to ask your allergist include:
Crustaceans like shrimp, lobster and crab tend to cause more allergic reactions. Of the crustaceans, shrimp causes the most allergies.
Shellfish allergies and fish allergies are different because they’re different animals. You may have a shellfish allergy but be able to eat fish (and vice versa). They’re both ocean animals, but fish have bones and fins, whereas a shellfish has a shell and no bones.
Shellfish allergies are sometimes confused with iodine allergies. That’s because shellfish often contain iodine. But having a shellfish allergy doesn’t necessarily mean you’re allergic to iodine. If you have a shellfish allergy, you don’t have to worry about reactions to radiocontrast material.
A note from Cleveland Clinic
A shellfish allergy can be annoying. It can interfere with your life, especially if you enjoy eating seafood. It’s smart to take precautions and avoid shellfish, even if you only experience mild symptoms. By avoiding shellfish, you can almost eliminate the uncomfortable (and potentially life-threatening) risks of an allergic reaction. If you notice symptoms after eating shellfish, talk to your healthcare provider or allergist to get a diagnosis. Your provider will talk to you about how to best care for yourself and explain how to use an epinephrine auto-injector.
Last reviewed by a Cleveland Clinic medical professional on 11/01/2023.
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