Have you ever sat down to have a bite of salmon or trout, only to find yourself breaking out in itchy hives or having trouble breathing? Although fish allergies are not as prevalent as reactions to peanuts or shellfish, they can be every bit as severe—and in some instances, even life-threatening.
What Causes a Fish Allergy?
Fish allergies occur when the immune system gets confused and attacks certain proteins in fish as harmful invaders. The primary protein responsible for these reactions is parvalbumin, which occurs in most finned fish such as tuna, salmon, halibut, and trout. If a person with an allergy to fish eats or even comes in contact with fish, their immune system goes into overdrive and starts releasing chemicals such as histamine that cause allergic reactions.
While some food allergies that children tend to grow out of, fish allergies become more likely later in life, and typically, they’re around to stay. They’re more prevalent in adults than children and occur more often in women. Those residing in countries where fish is a common part of the diet, such as in regions of Asia or Northern Europe, might also have a greater risk.
Symptoms to Watch For
Reactions usually take place within an hour after exposure and may range from mild to severe. It is usually characterized by:
- Itching or hives
- Stuffy or runny nose
- Headaches
- Swelling of the face, lips, or tongue
- Nausea, vomiting, or diarrhea
- Difficulty breathing
In the most severe instances, an individual may suffer from anaphylaxis—a rapid, body-wide allergic reaction that can lead to a decrease in blood pressure, difficulty in breathing, and even loss of consciousness. This is a medical emergency and must be treated immediately with epinephrine.
It’s Not Just About Eating Fish
For others, it’s not the eating of fish that triggers a response. Even exposure to cooking fumes, handling fish, or a kiss from someone who has just eaten fish is enough to bring on symptoms. As parvalbumin is similar in many types of fish, being allergic to one (such as trout) usually means reacting to others. This is cross-reactivity.
Getting a Diagnosis
If you think you have a fish allergy, begin by consulting an allergy specialist. Diagnosis usually involves:
- Skin prick testing, in which a small quantity of fish protein is introduced under your skin to observe for an allergic reaction
- Blood tests to detect IgE antibodies against certain fish proteins
- In other instances, a supervised food challenge might be suggested. This is eating a small quantity of fish while being closely watched medically to ensure that the allergy is present. Due to the severity of reactions it can cause for some individuals, the test is only administered in specialized clinics with ready access to emergency care.
Living Safely with a Fish Allergy
After being diagnosed, the most effective way to avoid a reaction is by not eating fish at all, including foods that harbor hidden fish ingredients. Fish proteins come unexpectedly in foods like:
- Caesar salad dressing
- Worcestershire sauce
- Certain processed meats (where fish gelatin is employed)
- Broths, bouillons, or sauces used in some cuisines
Always carefully check labels and ask questions when dining out, particularly at restaurants that have seafood on the menu. When in doubt, it’s best to err on the side of caution.
If your allergy is severe, carrying an epinephrine auto-injector (like an EpiPen) is a must. Antihistamines can help relieve mild symptoms like itching or a runny nose, but they’re not a substitute for epinephrine when it comes to anaphylaxis.
Hope on the Horizon
Certain new therapies, such as oral immunotherapy, are currently being studied to assist individuals in developing a tolerance to allergens. This is done by gradually exposing them to very small quantities of fish protein under strict medical supervision. Yet it’s still an experimental therapy and is only to be tried with the help of a trusted allergist.
Practical Tips for Day-to-Day Life
A fish allergy requires some planning, but it won’t dominate your existence. A few clever tips will make daily life safer:
- Have someone else shop for groceries or prepare fish at home.
- Select restaurants with allergy-conscious menus.
- Wear a medical alert bracelet.
- Inform close friends, family, and colleagues of your allergy and treatment in the event of an emergency.
Fish allergies are not as widely recognized as other food allergies, but they are no less dangerous. Armed with the right information, resources, and preparation, you can go through life safely and securely. Whether you’re self-managing symptoms or caring for a loved one, being informed is your best defense.
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