Overview
When you have a shellfish allergy and you eat shellfish, your body reacts as if the shellfish are trying to cause harm. It fights back by setting off an allergic reaction. A mild reaction may include a few raised, red, itchy patches of skin (called hives). A severe reaction may cause hives all over, swelling in the throat, trouble breathing, or fainting. It can also cause belly pain, nausea, vomiting, or diarrhea. This is called anaphylaxis (say "ANN-uh-fuh-LAK-suss"). It can be deadly.
A good way to prevent an allergic reaction is to avoid the foods that cause it. Shellfish might be used as ingredients in surimi (imitation shellfish, which is often found in sushi) and fish sauce. An allergy doctor or a dietitian may be able to help you understand which foods might be okay and what to avoid. Learn what to do if you have a reaction.
Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse advice line (811 in most provinces and territories) if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.
How can you care for yourself at home?
During a mild reaction
- Take a non-drowsy antihistamine, such as loratadine (Claritin), as your doctor recommends. Be safe with medicines. Read and follow all instructions on the label.
During a severe reaction
- Give yourself an epinephrine shot. Keep it with you at all times. Make sure it has not expired.
- Call for emergency help. A severe allergic reaction can be life-threatening and is a medical emergency.
To prevent future reactions
- Avoid the foods that cause problems. And try not to use utensils or cookware that may have been in contact with food that you are allergic to.
- Teach your family members, co-workers, and friends what to do if you have a severe reaction to a food that you are allergic to.
- Wear medical alert jewellery that lists your allergies.
When should you call for help?
Give an epinephrine shot if:
- You think you are having a severe allergic reaction.
After you give an epinephrine shot, call 911, even if you feel better.
Call 911 anytime you think you may need emergency care. For example, call if:
- You have symptoms of a severe allergic reaction. These may include:
- Sudden raised, red areas (hives) all over your body.
- Swelling of the throat, mouth, lips, or tongue.
- Trouble breathing.
- Passing out (losing consciousness). Or you may feel very light-headed or suddenly feel weak, confused, or restless.
- Severe belly pain, nausea, vomiting, or diarrhea.
- You have been given an epinephrine shot, even if you feel better.
Call your doctor or nurse advice line now or seek immediate medical care if:
- You have symptoms of an allergic reaction, such as:
- A rash or hives (raised, red areas on the skin).
- Itching.
- Swelling.
- Mild belly pain or nausea.
Watch closely for changes in your health, and be sure to contact your doctor or nurse advice line if:
- You do not get better as expected.
Where can you learn more?
Go to https://www.healthwise.net/patientEd
Enter S200 in the search box to learn more about "Shellfish Allergy: Care Instructions".
Current as of: February 26, 2023
Author: Healthwise Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.
