General Information

  • Reactions to food are common and can be divided into two categories, those caused by food allergy and all other reactions
  • Food allergies develop when the body’s immune system has an abnormal reaction to one or more proteins in a food that can lead to serious allergic reactions
  • Other food reactions are not caused by the immune system but can cause unpleasant symptoms (examples include lactose intolerance, heartburn, food poisoning, and sensitivities)
  • Shellfish allergy is one of the most common food allergies
  • The majority of people experience their first reaction to shellfish as an adult
  • Shellfish allergy can occur after eating the food on a regular basis without reaction

Shellfish Avoidance

  • Tell anyone with regular contact with you or your child about the allergy and avoidance of shellfish
  • Read labels every time you buy something. Manufacturers can change products at any time - Be aware of cross contamination (transfer of shellfish to a food that does not normally have shellfish as an ingredient)
  • Very sensitive people can react if they are close to where shellfish is being cooked or fried
  • About 75% of people with shellfish allergy will have reactions to more than one type of shellfish
  • Shrimp, crab and lobster cause most shellfish allergies
  • Only 10% of people with shellfish allergy have allergies to fish (being allergic to shellfish does not always mean avoiding fish as well)
  • Shellfish are divided into crustaceans (lobster, crab, shrimp) and mollusks (clams, mussels, oyster, scallops)
  • Common shellfish include:
    • Abalone
    • Krill
    • Quahaugs
    • Barnacle
    • Limpets
    • Sea cucumber
    • Clam
    • Lobster
    • Sea urchin
    • Crab
    • Mussels
    • Scallops
    • Crayfish / crawfish
    • Octopus
    • Shrimp / crevette / scampi
    • Cockle
    • Oysters
    • Snails / escargot
    • Conch
    • Periwinkle
    • Squid / calamari
    • Cuttlefish
    • Prawns
    • Whelks
  • Some foods that contain or may contain shellfish
    • Caviar
    • Imitation crab / lobster
    • Scrob
    • Ceviche
    • Kamaboko
    • Surimi
    • Gravad lax
    • Minced fillets
    • Sushi
    • Fish stock
    • Sashimi
    • Tarama

Allergic Reactions

  • Symptoms often occur within minutes up to 2 hours of exposure to shellfish
  • Outside Symptoms
    • Face: Redness, itchy eyes / nose, swelling
    • Skin: Itching, redness, hives, swelling
  • Inside Symptoms
    • Face: Swelling lips and tongue, itchy mouth
    • Throat: Itching, tightness, hoarse voice, cough
    • Lungs: Trouble breathing, shortness of breath
    • Stomach: Vomiting, nausea, stomach pain, diarrhea
    • General: Dizzy, unsteady, drowsy, fainting
  • Not every reaction will look the same, a person can have different symptoms each time
  • Symptoms range from mild to life threatening, there is no way to predict if the reaction will be mild or severe
  • Anaphylaxis is a severe life threatening reaction with more than one body system affected (skin, breathing, stomach, general) and can occur WITHOUT skin symptoms such as hives

Treatment of Reactions

  • Antihistamines such as Benadryl will NOT stop severe reactions
  • An epinephrine auto injector such as Allerject or EpiPen MUST be available at all times
  • If you are visiting an area without access to a hospital you should have 2 auto injectors available
  • A medical identification device such a Medical Alert bracelet should be worn to outline the food allergy and that an epinephrine auto injector is carried
  • Give epinephrine in the outer thigh if there are any of the following symptoms (listed in the table on the previous page)
    • General symptoms
    • Severe outside symptoms
    • Any inside symptoms
    • If you are in doubt, give the epinephrine
  • After epinephrine is given
    • Lie down / lie your child down
    • Call local emergency service and tell them someone is having an allergic reaction
    • If the reaction continues or worsens, give a second dose of epinephrine in 5 - 15 minutes (there is only 1 dose of epinephrine in each auto injector, a second dose requires a new auto-injector)
    • Go to the nearest emergency room even if the symptoms are gone because the reaction can worsen or come back
    • Stay in the hospital for at least 4 - 6 hours of observation

Outcomes for Shellfish Allergic Patients

  • The majority of people do not outgrow the shellfish allergy
  • Repeat skin testing and blood work every 1 - 2 years will help determine if the allergy is outgrown
  • An oral food challenge (eating shellfish in small steps ONLY in the doctors office) will be offered if your doctor feels it is safe
  • Shellfish products should NEVER be tried outside of a doctors office to see if the shellfish allergy is outgrown

Additional information: www.anaphylaxis.ca or www.foodallergy.org