Fish
Allergy Facts, Symptoms, and Treatment

Comprising more than 30,000 species, fish is a source of proteins, healthy fats, omega-3 fatty acids, iodine, vitamin D, and calcium.1,2 In many developing countries, fish is the main or only source of animal protein, and due to the current focus on health and nutrition, there's also an increased demand for fish in developed and middle-income nations.2 Fish is consumed in a variety of ways, and fish eggs, caviar, skin, gelatin, and blood may all elicit allergic reactions. Fish muscle can be eaten cooked, fried, pickled, and raw, but heating and processing doesn t seem to affect allergy potency. Rather, allergenicity varies by species.1 Incorporated in raw, powdered, and oil forms, fish is also included in processed foods, and fish-based gelatin and collagen products can be used in nonfood items such as pharmaceutical gel capsules and vaccines.1,3

Despite its nutritional importance and many uses, fish is one of the most common causes of food allergy, and according to a review of recent research, fish allergy was self reported by 2.2 percent of the European population.3,4 In the United States, fish is one of the top eight food allergens, and fish allergy particularly impacts adults in Scandinavian countries.3,5 Although many food allergies develop in childhood, roughly 40 percent of those allergic to fish experience their first reactions as adults.5,6

Unfortunately, if you're allergic to one type of fish, you have an increased risk of reacting to others. Plus, there's a high risk of cross-contamination with other fish species in environments such as fish markets and supermarkets. For those reasons, people with fish allergy are normally advised to avoid all types of fish.7

Where is fish found?

Fish muscle is eaten cooked, fried, pickled, and raw, but fish eggs, caviar, skin, gelatin, and blood also have provoked fish allergy symptoms. Plus, fish and fish based gelatins and collagens can be unexpected ingredients in a host of foods and nonfood items, such as pharmaceutical gel capsules and vaccines.1 And while fish is identified on most food labels, if fish is part of an oil, it may not be listed.3

On food labels, fish may be identified as such or may be listed as any of the following:6 anchovies, bass, catfish, cod, flounder, grouper, haddock, hake, halibut, herring, mahi, perch, pike, pollock, salmon, scrod, sole, snapper, swordfish, tilapia, trout, and tuna.

Foods that may contain fish proteins include:6,7 barbecue sauce, bouillabaisse, Caesar salads and dressings, caponata (a Sicilian eggplant relish), etouffee, fish oil, fish sauce, fish sticks, fritto misto, gelatin (often made from fish skin and bones), gumbo, imitation or artificial fish or shellfish (e.g., surimi, sea legs, sea sticks), jambalaya, kedgeree (a fish and rice dish), paella, stocks, soups, and Worcestershire sauce.

Unfortunately, there's a high risk of cross-contamination in food prep areas, and as such, it may be best to avoid all seafood restaurants, even if you plan to order something other than fish.5 Also be wary of restaurants with African, Chinese, Indonesian, Thai, and Vietnamese cuisines, which regularly incorporate fish, as the risk of cross-contamination is high in these environments.6 This hazard also extends to frying oils. For example, if French fries (chips) were fried in the same oil as fish, the oil could contain traces of fish proteins, which may be passed along to the French fries.7 Also be wary of filleted fish. According to a recent investigation, supermarkets and restaurants may substitute cheaper fish varieties for more expensive types since many fish species look similar once filleted. For example, an establishment might list an item as red snapper when in fact it might be tilapia. So it's critical to explain your fish allergy to anyone handling your fish to ensure you receive the species you're expecting.5

Since it's possible to be allergic to fish gelatin, which is derived from fish skin and bones, you could also react to dietary supplements containing fish oil.5 This oil may be included in items such as cosmetics, toiletries, medicines, and bath and massage oils. And although research hasn't definitively identified omega-3 supplements derived from fish as known allergen triggers, it's still safest to avoid any such products if you are allergic to fish.7 If your allergy is severe, you may react to the vapor or steam present in environments where fish is being cooked. As a result, allergic reactions among workers in the seafood industry are common and include occupational asthma, contact rashes, allergic rhinitis (aka hay fever), and conjunctivitis (aka pink eye).7

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Are there other allergens I could be sensitized to?*

Most people with fish allergy may experience symptoms when eating different types of fish. This is called cross-reactivity and occurs when your body's immune system identifies the proteins, or components, in different substances as being structurally similar or biologically related, thus triggering a response. The most common cross-reactivities with fish are other types of bone fish such as salmon, cod, tuna, herring, carp, pilchard, sole, and trout.1

Fish consist of different types of proteins that all have different characteristics and implications. Knowing the proteins, or components, within each allergen that are triggering your symptoms can help guide your management plan. With that in mind, and based on your symptom history, your healthcare provider may suggest something called a specific IgE component test, which can help reveal the risk profile you belong to.2

Already have your specific IgE component test results?

Your component test results will include the name of the components (a series of letters and numbers and/or name). Your healthcare provider will likely review the results with you, but here you'll find an at-a-glance breakdown you can use as a reference. Simply match the component names to the list below to see what they mean in terms of symptom management.1

rCyp c 1

  • Strong cross-reactivity exists between fish, meaning symptoms may appear after ingesting different species of fish. 
  • Highly heat stable, meaning both raw and extensively cooked food may cause symptoms.

rGad c 1 

  • Strong cross-reactivity exists between fish, meaning symptoms may appear after ingesting different species of fish. 
  • Heat stable, meaning both raw and extensively cooked food may cause symptoms.

Test results should be interpreted by your healthcare provider in the context of your clinical history. Final diagnosis and decision on further management is made by your healthcare provider.

Do I need to avoid all forms of fish?

Note that if you're allergic to one type of fish, you have an increased risk of reacting to others. As such, those allergic to fish are often advised to avoid consumption of any type of fish.

However, just because you're allergic to fish doesn t necessarily mean you're also allergic to shellfish.5 But given the risk for cross-contamination between shellfish and fish, exert caution when consuming shellfish that may have been exposed to fish prior to or during cooking or preparation.5,7 In addition, there's a high risk of cross-contamination with other fish and shellfish species in environments such as fish markets and supermarkets.7

*These products may not be approved for clinical use in your country. Please work with your healthcare provider to understand availability.

How do I manage my allergy?

Because there is no cure for food allergies, your healthcare provider may recommend a plan that includes the following. 5,7,11-14

  • Be especially wary of all food in environments where fish is being actively cooked or processed, such as restaurants and kitchens, due to cross-contamination risks.
  • Inquire about cross-contamination with frying oils. If fish has been fried in an oil, it may retain trace amounts of fish protein, which can be passed on to other food items fried  in the same oil.
  • Make anyone providing you with fish aware of your allergy to ensure you receive the specific species you request.
  • Read ingredient labels and "may contain" advisory panels on food and nonfood products carefully, and avoid all foods and products containing any form of the allergen. Note that these lists and panels may not appear on the same side of a product's packaging and that manufacturers frequently change ingredients. If you're unable to obtain a list of ingredients, it's safest to avoid that item.
  • Avoid cross-contamination when cooking by using two sets of cooking and eating utensils, with one exclusively for the allergic individual. Wash all dishes and utensils in hot soapy water between uses.
  • Craft an action plan with a list of steps for you and others to take should you accidentally ingest the allergen. Print out a copy of the plan and carry it with you.
  • Talk with restaurant chefs about your allergy and order food that's simply prepared and void of any form of the allergen. Avoid desserts, as they often contain or have come into contact with food allergens.
  • Plan ahead for traveling to ensure your food allergy will be managed and any emergency medication is always available.
  • Wear a medical ID bracelet identifying the allergen to which you're allergic.
  • Carry any recommended or emergency medication with you at all times.
  • Teach children with food allergies which foods to avoid. Work with caregivers and school staff to eliminate or reduce exposure to the allergen and to ensure they understand when and how to use medication to treat symptoms.

Your healthcare provider may direct you to take one of the following medications:

  • Epinephrine auto-injector when there are signs of an acute severe event, aka anaphylaxis (see below). Ensure your family members know how to administer it in case of an emergency.
  • Antihistamines as a supplement may be useful in relieving mild symptoms (e.g., itch); however, they do not halt the progression of an allergic reaction.
  • Bronchodilator (albuterol) as a supplemental therapy for respiratory symptoms, especially in those with a history of bronchospasm or asthma.

If you're with someone who's having an allergic reaction and shows signs of shock, act fast. Look for pale, cool, and clammy skin; a weak, rapid pulse; trouble breathing; confusion; and loss of consciousness. Do the following immediately:

  • Call local emergency services.
  • Ensure the affected individual is lying down with legs elevated.
  • Administer epinephrine immediately for any obvious signs of anaphylaxis.
  • Check the affected individual's pulse and breathing and administer CPR or other first-aid measures if necessary.

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Fish Allergen Facts, Symptoms, and Treatment

Common Symptoms

Fish allergy can range from mild to severe and may vary over time, resulting in mild symptoms during one episode and severe symptoms in another. Although food allergy symptoms can start a few minutes to several hours after ingestion, most begin within two hours.8 Symptoms may involve the skin, gastrointestinal tract, cardiovascular system, and respiratory tract, and may include one or more of the following:8,9

  • Abdominal pain, diarrhea, nausea, vomiting, stomach cramps
  • Hives (allergic urticaria), itching, eczema
  • Wheezing, nasal congestion, shortness of breath, repetitive cough
  • Shock, circulatory collapse
  • Tight, hoarse throat, trouble swallowing
  • Pale or blue skin coloring
  • Dizziness, lightheadedness, fainting, weak pulse
  • Anaphylaxis, a potentially life-threating event

Those allergic to fish may also react to steam and vapors present in environments where fish is being cooked.7

As such, allergic reactions among workers in the seafood industry are common and include occupational asthma, contact rashes, allergic rhinitis (aka hay fever), and conjunctivitis (aka pink eye).7 Airborne fish particles can also trigger atopic dermatitis (aka eczema).10

How do I know if I'm allergic?*

Together with your symptom history, skin-prick testing or specific IgE blood testing can help determine if you are allergic to a particular allergen. If you are diagnosed with an allergy, your healthcare provider will work with you to create a management plan.

*These products may not be approved for clinical use in your country. Please work with your healthcare provider to understand availability.

Is there a risk for a severe event?

Because food allergic reactions are unpredictable and symptoms range from local to systemic, it is recommended that an epinephrine prescription be considered for any patient with an IgE-mediated food allergy.11

If you have asthma, you may face a higher risk of severe fish reactions, particularly if your asthma is poorly controlled.7

  1. EAACI, et al. Molecular allergology user's guide. Pediatr Allergy Immunol. 2016 May;27 Suppl 23:1-250. doi: 10.1111/pai.12563. PMID: 27288833. (178-180 p.) Available from: http://www.eaaci.org/documents/Molecular_Allergology-web.pdf.
  2. Food and Agriculture Organization of the United Nations [Internet]. Rome, Italy: Food and Agriculture Organization of the United Nations; 2020. Available from:
    http://www.fao.org/fileadmin/user_upload/newsroom/docs/BlueGrowthNutritionRev2.pdf
  3. Steinman HA. Hidden allergens in foods. J Allergy Clin Immunol. 1996;98:241-50.
  4. Nwaru BI, Hickstein L, Panesar SS, Roberts G, Muraro A, Sheikh A; EAACI Food Allergy and Anaphylaxis Guidelines Group. Prevalence of common food allergies in Europe: a systematic review and meta-analysis. Allergy. 2014 Aug;69(8):992-1007. doi: 10.1111/all.12423. Epub 2014 May 10. PMID: 24816523.
  5. American College of Allergy, Asthma & Immunology [Internet]. Arlington Heights, IL: American College of Allergy, Asthma & Immunology; 2019 Mar 21. Available from: https://acaai.org/allergies/types/food-allergies/types-food-allergy/fish-allergy.
  6. Food Allergy Research & Education [Internet]. McLean, VA: Food Allergy Research & Education; 2020. Available from: https://www.foodallergy.org/living-food-allergies/food-allergy-essentials/common-allergens/fish.
  7. The Anaphylaxis Campaign [Internet]. Farnborough, UK: The Anaphylaxis Campaign; 2019 Sep. Available from: https://www.anaphylaxis.org.uk/wp-content/uploads/2019/09/Fish-Sep-2019.pdf.
  8. American College of Allergy, Asthma & Immunology [Internet]. Arlington Heights, IL: American College of Allergy, Asthma & Immunology; 2014. Available from: https://acaai.org/allergies/types/food-allergy.
  9. Mayo Clinic [Internet]. Rochester, MN: Mayo Foundation for Medical Education and Research; 2019 Nov 2. Available from: https://www.mayoclinic.org/diseases-conditions/food-allergy/symptoms-causes/syc-20355095.
  10. Kuehn A, Swoboda I, Arumugam K, Hilger C, Hentges F. Fish allergens at a glance: variable allergenicity of parvalbumins, the major fish allergens. Front Immunol. 2014 Apr 22;5:179. doi: 10.3389/fimmu.2014.00179. PMID: 24795722; PMCID: PMC4001008.. 
  11. Wright BL, Walkner M, Vickery BP, Gupta RS. Clinical Management of Food Allergy. Pediatr Clin North Am. 2015 Dec;62(6):1409-24. doi: 10.1016/j.pcl.2015.07.012. Epub 2015 Sep 7. PMID: 26456440; PMCID: PMC4960977.
  12. American College of Allergy, Asthma & Immunology [Internet]. Arlington Heights, IL: American College of Allergy, Asthma & Immunology; 2014. Available from: https://acaai.org/allergies/types-allergies/food-allergy/food-allergy-avoidance.
  13. Harvard Health Publishing [Internet]. Boston, MA: Harvard Medical School; 2020. Available from: https://www.health.harvard.edu/healthbeat/6-tips-for-managing-food-allergies.
  14. Mayo Clinic [Internet]. Rochester, MN: Mayo Foundation for Medical Education and Research; 2019 Sep 14. Available from: https://www.mayoclinic.org/diseases-conditions/anaphylaxis/symptoms-causes/syc-20351468.
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