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[Bezzy Psoriasis](https://www.bezzypsoriasis.com/?utm_source=mnt&utm_medium=nav-bar-connect) ### Follow Us Subscribe # What to know about shellfish allergies  [Medically reviewed]() by [Elaine K. Luo, M.D.]() — Written by [Nicole Galan, RN]() on June 25, 2019 - [Symptoms](https://www.medicalnewstoday.com/articles/325559#symptoms) - [Causes](https://www.medicalnewstoday.com/articles/325559#causes) - [Treatment](https://www.medicalnewstoday.com/articles/325559#treatment) - [At home](https://www.medicalnewstoday.com/articles/325559#at-home) - [Prevalence](https://www.medicalnewstoday.com/articles/325559#prevalence) - [Summary](https://www.medicalnewstoday.com/articles/325559#summary) The main symptoms of a shellfish allergy vary, but they can include vomiting, diarrhea, stomach pain, shortness of breath, coughing, chest pain, and swelling of the face, lips, tongue, or throat. How long symptoms last can vary. These symptoms can occur within minutes of ingesting shellfish, but they may sometimes not appear for several hours. There are two [different types](https://www.hopkinsallchildrens.org/Patients-Families/Health-Library/HealthDocNew/Shellfish-Allergy-\(1\)) of shellfish: 1. **Crustaceans**: Shrimp, crab, lobster 2. **Mollusks**: Clams, mussels, oysters, scallops, squid, octopus Some people are allergic to one type of shellfish, while others are allergic to both. [Most people](https://acaai.org/allergies/types/food-allergies/types-food-allergy/shellfish-allergy) with a shellfish allergy seem to be allergic to crustaceans, and the reactions to these foods tend to be more severe. The doctor may recommend that people with any type of shellfish allergy avoid all shellfish due to the risk of cross-contamination or the development of new allergies. ## [Symptoms]()  [Share on Pinterest](https://www.pinterest.com/pin/create/button/?url=https%3A%2F%2Fwww.medicalnewstoday.com%2Farticles%2F325559&media=https%3A%2F%2Fpost.medicalnewstoday.com%2Fwp-content%2Fuploads%2Fsites%2F3%2F2019%2F06%2Fclams-table-shellfish-allergies-1296x728-header-1024x575.jpg&description=Shellfish%20allergy%20symptoms%3A%20How%20long%20they%20last%20and%20treatments "Share on Pinterest") Ellie Baygulov/Stocksy The symptoms of a shellfish allergy may include: - [indigestion](https://www.medicalnewstoday.com/articles/163484.php "What to know about indigestion or dyspepsia") - vomiting - stomach pain - [diarrhea](https://www.medicalnewstoday.com/articles/158634.php "What you should know about diarrhea") - wheezing - shortness of breath - coughing - a tight throat or a hoarse voice - pale or blue discoloration of the skin - an itchy rash, or [hives](https://www.medicalnewstoday.com/articles/157260.php "What are hives (urticaria)?") - swelling in the mouth or throat - dizziness - confusion - loss of consciousness The symptoms of a shellfish allergy can vary among individuals and from one reaction to another. Sometimes, a reaction can be very mild and short, and other times, it can be more severe and last longer. Reactions tend to worsen over time. ### In children Babies and children will experience the same allergy [signs and symptoms](https://www.healthychildren.org/English/ages-stages/baby/feeding-nutrition/Pages/Food-Allergy-Reactions.aspx) as adults. It is important to recognize that a young child may not be able to verbalize what they are experiencing. Parents and caregivers will need to look for hives and signs that the baby is struggling to breathe. These signs may include the skin and muscles around the ribs pulling in when the baby takes a breath or the skin around the lips and nail beds turning blue. ### Severe reactions A very severe allergy can trigger [anaphylaxis](https://www.medicalnewstoday.com/articles/216062.php "Anaphylaxis: Signs, causes, and treatment"), which is a severe, life-threatening reaction that involves multiple body systems. This reaction can occur within minutes or even seconds of exposure to shellfish. It can become severe very quickly and can also be deadly without prompt treatment. Signs of anaphylaxis include: - trouble breathing - swelling of the throat - wheezing - coughing - nausea or vomiting - stomach pain - a stuffy nose - a rapid heartbeat People who have serious symptoms, such as shortness of breath, wheezing, or swelling of the throat, and those with symptoms affecting two different body systems, such as hives and a stomachache, should immediately seek emergency care. If they have a prescription for epinephrine, they should also administer this drug. It is still essential to seek emergency care after administering the epinephrine. Quite often, a second round of severe symptoms, which people call a biphasic reaction, will occur several hours later. ## [Causes]() Shellfish allergies occur when the body’s immune system reacts against the proteins present in these animals. When someone with an allergy has exposure to the protein, the immune system goes into overdrive and tries to fight off the foreign invader. Part of this reaction involves the release of histamine, which is a chemical that causes the symptoms of the allergy. For this reason, antihistamines can be effective against allergic reactions. ## [Treatment]() If a doctor suspects that a person may have a shellfish allergy, they are likely to refer them to an allergist for further diagnostic testing. If these tests confirm the presence of an allergy, the only treatment is to avoid shellfish altogether. Doctors may prescribe people who have a serious allergy with an epinephrine auto-injector to carry with them. In the event of exposure or a serious reaction, every second counts. Administering epinephrine at an early stage of the reaction can help prevent it from becoming worse and potentially deadly. ## [Caring for a shellfish allergy at home]() There are no home remedies for a shellfish allergy, but being under the care of a doctor or seeking emergency care after exposure is essential. However, people can often manage a shellfish allergy by learning how to read nutritional labels to avoid the allergen. While food producers must include an allergen statement on foods containing crustacean shellfish, the same is not true of mollusks. However, people can find this information in the ingredients list instead. ### Avoiding shellfish in restaurants When going out to eat, it is very important to let the host or restaurant staff know about a [food allergy](https://www.medicalnewstoday.com/articles/14384.php "Food allergies: What you need to know") beforehand as there may be a potential risk of cross-contamination of food dishes or cooking materials. Someone with a severe allergy may even need to stay away from the [fumes or vapors](https://www.foodallergy.org/sites/default/files/migrated-files/file/food-allergy-faqs.pdf) that can come out of a kitchen where people are preparing shellfish dishes. People should not hesitate to let the waitstaff know if that is a potential trigger for an allergic reaction. ### Other products containing shellfish People can find shellfish ingredients in items other than food, including some nutritional supplements, pet foods, fertilizers, and cosmetic products. Anyone with concerns about a specific product can try calling the company phone number to get detailed information about the ingredients. ## [Prevalence]() Shellfish allergies are among the most common food allergies. A [study](https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2720064) that recruited more than 40,000 participants from the United States reported that about 2.9% of them were living with a shellfish allergy. What is unique about a shellfish allergy is that although it can occur in people of any age, it tends to develop in adulthood rather than childhood. Once they have developed, shellfish allergies tend to be lifelong. It is important to recognize that having a shellfish allergy is different than having a seafood or fish allergy. Many people who are allergic to shellfish are still able to eat finned fish because they are not the same biologically. ## [Summary]() It can sometimes seem challenging to live with a food allergy. However, thanks to improved labeling practices and a greater awareness of food allergies, it is now easier to manage an allergy than it has been previously. It is important for people to be aware of the symptoms of an allergic reaction, even those who have not reacted to shellfish or other foods before. An allergy can worsen over time, so anyone who reacts to shellfish should check in with their doctor for further evaluation and testing. - [Allergy](https://www.medicalnewstoday.com/categories/allergy) - [Food Allergy](https://www.medicalnewstoday.com/categories/food-allergy) - [GastroIntestinal / Gastroenterology](https://www.medicalnewstoday.com/categories/gastrointestinal) - [Nutrition / Diet](https://www.medicalnewstoday.com/categories/nutrition-diet) ### How we reviewed this article: Sources Medical News Today has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our [editorial policy](https://www.medicalnewstoday.com/articles/process). - Food allergies: Frequently asked questions. (n.d.). <https://www.foodallergy.org/sites/default/files/migrated-files/file/food-allergy-faqs.pdf> - Food allergy reactions. (2009). <https://www.healthychildren.org/English/ages-stages/baby/feeding-nutrition/Pages/Food-Allergy-Reactions.aspx> - Gupta, R. S., *et al.* (2019). Prevalence and severity of food allergies among US adults. <https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2720064> - Shellfish allergy. (2018). <https://kidshealth.org/en/parents/shellfish-allergy.html> - Shellfish allergy. (2019). <https://acaai.org/allergies/types/food-allergies/types-food-allergy/shellfish-allergy> - Shellfish allergy. (n.d.). <https://www.foodallergy.org/common-allergens/shellfish-allergy> - Shellfish allergy. (n.d.). <https://www.hopkinsallchildrens.org/Patients-Families/Health-Library/HealthDocNew/Shellfish-Allergy-(1)> Share this article  [Medically reviewed]() by [Elaine K. Luo, M.D.]() — Written by [Nicole Galan, RN]() on June 25, 2019 ## Latest news - [Two days of oatmeal may help reduce 'bad' cholesterol levels, study finds](https://www.medicalnewstoday.com/articles/two-days-oatmeal-reduce-ldl-cholesterol-levels-study) - [Is sleep the missing piece in mental health?](https://www.medicalnewstoday.com/articles/is-sleep-the-missing-piece-in-mental-health) - [Is this why dementia affects more women? How menopause alters the brain](https://www.medicalnewstoday.com/articles/dementia-menopause-brain-health-gray-matter-memory-loss) - [Low dose aspirin does not reduce cancer risk in older adults, long-term study finds](https://www.medicalnewstoday.com/articles/low-dose-aspirin-does-not-reduce-cancer-risk-in-older-adults) - [Can treating rheumatoid arthritis before it sets in help delay its onset?](https://www.medicalnewstoday.com/articles/pretreatment-rheumatoid-arthritis-onset-delay-4-years) ### Related Coverage - [Can you have a garlic allergy?](https://www.medicalnewstoday.com/articles/321702?utm_source=ReadNext) Medically reviewed by [Natalie Olsen, R.D., L.D., ACSM EP-C](https://www.medicalnewstoday.com/reviewers) [A garlic allergy is rare, but it is possible. In this article, we look at the symptoms of a true allergy, which include sneezing, dizziness, and in…](https://www.medicalnewstoday.com/articles/321702?utm_source=ReadNext) [READ MORE](https://www.medicalnewstoday.com/articles/321702?utm_source=ReadNext) - [How to cope with your food allergy](https://www.medicalnewstoday.com/articles/321159?utm_source=ReadNext) [The only way to prevent allergic reactions if you have a food allergy is to avoid the allergen. Here are some tips to help you cope with food…](https://www.medicalnewstoday.com/articles/321159?utm_source=ReadNext) [READ MORE](https://www.medicalnewstoday.com/articles/321159?utm_source=ReadNext) - [Eggplant allergy: What you need to know](https://www.medicalnewstoday.com/articles/319874?utm_source=ReadNext) Medically reviewed by [Natalie Butler, R.D., L.D.](https://www.medicalnewstoday.com/reviewers) [Allergies to eggplant, or aubergine, are fairly uncommon. Eggplants belong to the nightshade family, which include tomatoes. Anyone with a tomato or…](https://www.medicalnewstoday.com/articles/319874?utm_source=ReadNext) [READ MORE](https://www.medicalnewstoday.com/articles/319874?utm_source=ReadNext) - [Xolair food allergy treatment](https://www.medicalnewstoday.com/articles/drugs-xolair-food-allergy-treatment?utm_source=ReadNext) [Xolair is a prescription drug used to treat food allergies and other conditions. Learn more about the drug, how it works for food allergies, its…](https://www.medicalnewstoday.com/articles/drugs-xolair-food-allergy-treatment?utm_source=ReadNext) [READ MORE](https://www.medicalnewstoday.com/articles/drugs-xolair-food-allergy-treatment?utm_source=ReadNext) - [Rare food allergy may affect more children than previously thought](https://www.medicalnewstoday.com/articles/rare-food-allergy-may-affect-more-children-than-previously-thought?utm_source=ReadNext) [Researchers are reporting that food allergies such as eosinophilic esophagitis can "march" through some children](https://www.medicalnewstoday.com/articles/rare-food-allergy-may-affect-more-children-than-previously-thought?utm_source=ReadNext) [READ MORE](https://www.medicalnewstoday.com/articles/rare-food-allergy-may-affect-more-children-than-previously-thought?utm_source=ReadNext) © 2026 Healthline Media UK Ltd, London, UK. All rights reserved. MNT is the registered trade mark of Healthline Media. 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The main symptoms of a shellfish allergy vary, but they can include vomiting, diarrhea, stomach pain, shortness of breath, coughing, chest pain, and swelling of the face, lips, tongue, or throat. How long symptoms last can vary. These symptoms can occur within minutes of ingesting shellfish, but they may sometimes not appear for several hours. 1. **Crustaceans**: Shrimp, crab, lobster 2. **Mollusks**: Clams, mussels, oysters, scallops, squid, octopus Some people are allergic to one type of shellfish, while others are allergic to both. [Most people](https://acaai.org/allergies/types/food-allergies/types-food-allergy/shellfish-allergy) with a shellfish allergy seem to be allergic to crustaceans, and the reactions to these foods tend to be more severe. The doctor may recommend that people with any type of shellfish allergy avoid all shellfish due to the risk of cross-contamination or the development of new allergies. The symptoms of a shellfish allergy may include: - [indigestion](https://www.medicalnewstoday.com/articles/163484.php "What to know about indigestion or dyspepsia") - vomiting - stomach pain - [diarrhea](https://www.medicalnewstoday.com/articles/158634.php "What you should know about diarrhea") - wheezing - shortness of breath - coughing - a tight throat or a hoarse voice - pale or blue discoloration of the skin - an itchy rash, or [hives](https://www.medicalnewstoday.com/articles/157260.php "What are hives (urticaria)?") - swelling in the mouth or throat - dizziness - confusion - loss of consciousness The symptoms of a shellfish allergy can vary among individuals and from one reaction to another. Sometimes, a reaction can be very mild and short, and other times, it can be more severe and last longer. Reactions tend to worsen over time. In children Babies and children will experience the same allergy [signs and symptoms](https://www.healthychildren.org/English/ages-stages/baby/feeding-nutrition/Pages/Food-Allergy-Reactions.aspx) as adults. It is important to recognize that a young child may not be able to verbalize what they are experiencing. Parents and caregivers will need to look for hives and signs that the baby is struggling to breathe. These signs may include the skin and muscles around the ribs pulling in when the baby takes a breath or the skin around the lips and nail beds turning blue. Severe reactions A very severe allergy can trigger [anaphylaxis](https://www.medicalnewstoday.com/articles/216062.php "Anaphylaxis: Signs, causes, and treatment"), which is a severe, life-threatening reaction that involves multiple body systems. This reaction can occur within minutes or even seconds of exposure to shellfish. It can become severe very quickly and can also be deadly without prompt treatment. Signs of anaphylaxis include: - trouble breathing - swelling of the throat - wheezing - coughing - nausea or vomiting - stomach pain - a stuffy nose - a rapid heartbeat People who have serious symptoms, such as shortness of breath, wheezing, or swelling of the throat, and those with symptoms affecting two different body systems, such as hives and a stomachache, should immediately seek emergency care. If they have a prescription for epinephrine, they should also administer this drug. It is still essential to seek emergency care after administering the epinephrine. Quite often, a second round of severe symptoms, which people call a biphasic reaction, will occur several hours later. Shellfish allergies occur when the body’s immune system reacts against the proteins present in these animals. When someone with an allergy has exposure to the protein, the immune system goes into overdrive and tries to fight off the foreign invader. Part of this reaction involves the release of histamine, which is a chemical that causes the symptoms of the allergy. For this reason, antihistamines can be effective against allergic reactions. If a doctor suspects that a person may have a shellfish allergy, they are likely to refer them to an allergist for further diagnostic testing. If these tests confirm the presence of an allergy, the only treatment is to avoid shellfish altogether. Doctors may prescribe people who have a serious allergy with an epinephrine auto-injector to carry with them. In the event of exposure or a serious reaction, every second counts. Administering epinephrine at an early stage of the reaction can help prevent it from becoming worse and potentially deadly. There are no home remedies for a shellfish allergy, but being under the care of a doctor or seeking emergency care after exposure is essential. However, people can often manage a shellfish allergy by learning how to read nutritional labels to avoid the allergen. While food producers must include an allergen statement on foods containing crustacean shellfish, the same is not true of mollusks. However, people can find this information in the ingredients list instead. Avoiding shellfish in restaurants When going out to eat, it is very important to let the host or restaurant staff know about a [food allergy](https://www.medicalnewstoday.com/articles/14384.php "Food allergies: What you need to know") beforehand as there may be a potential risk of cross-contamination of food dishes or cooking materials. Someone with a severe allergy may even need to stay away from the [fumes or vapors](https://www.foodallergy.org/sites/default/files/migrated-files/file/food-allergy-faqs.pdf) that can come out of a kitchen where people are preparing shellfish dishes. People should not hesitate to let the waitstaff know if that is a potential trigger for an allergic reaction. Other products containing shellfish People can find shellfish ingredients in items other than food, including some nutritional supplements, pet foods, fertilizers, and cosmetic products. Anyone with concerns about a specific product can try calling the company phone number to get detailed information about the ingredients. Shellfish allergies are among the most common food allergies. A [study](https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2720064) that recruited more than 40,000 participants from the United States reported that about 2.9% of them were living with a shellfish allergy. What is unique about a shellfish allergy is that although it can occur in people of any age, it tends to develop in adulthood rather than childhood. Once they have developed, shellfish allergies tend to be lifelong. It is important to recognize that having a shellfish allergy is different than having a seafood or fish allergy. Many people who are allergic to shellfish are still able to eat finned fish because they are not the same biologically. It can sometimes seem challenging to live with a food allergy. However, thanks to improved labeling practices and a greater awareness of food allergies, it is now easier to manage an allergy than it has been previously. It is important for people to be aware of the symptoms of an allergic reaction, even those who have not reacted to shellfish or other foods before. An allergy can worsen over time, so anyone who reacts to shellfish should check in with their doctor for further evaluation and testing.