Cod allergy
Allergy to cod.
About cod allergy
Cod is a popular white fish and one of the most commonly reported causes of fish allergy. Fish is a named allergen on UK food labels, and cod allergy is an IgE-mediated allergy that usually begins in childhood and often lasts a lifetime. The immune system typically reacts to a fish muscle protein called parvalbumin, and exposure triggers a rapid release of histamine and other chemicals responsible for the reaction.
Fish allergy, including cod, is well known for causing rapid and potentially severe reactions. Symptoms usually begin within minutes of eating and can range from an itchy mouth, hives and swelling to vomiting, wheezing and, at the severe end, anaphylaxis with breathing difficulty or collapse. Because parvalbumin is shared across many fish species, people allergic to cod often react to other bony fish such as haddock, plaice and salmon. Cooking steam and vapours from fish can trigger symptoms in highly sensitive people, and shellfish are a separate allergen group, so a cod allergy does not automatically mean shellfish must be avoided.
Diagnosis is made by an allergy specialist using skin-prick or specific-IgE blood tests, sometimes with a supervised food challenge. Management means strict avoidance of cod and, depending on testing, other fish, with careful attention to fish sauces, stock, Worcestershire sauce and cross-contamination in fried foods. People at risk of severe reactions are prescribed an adrenaline auto-injector. A severe reaction is a medical emergency: use adrenaline and call 999.
Common triggers
- Cod and products containing it
Symptoms
- Itching or tingling in the mouth
- Hives, itching or eczema
- Swelling of the lips, face, tongue or throat
- Stomach cramps, nausea, vomiting or diarrhoea
- Wheezing or trouble breathing
- In severe cases, anaphylaxis
Avoidance & management
- Read ingredient labels every time
- Ask about ingredients and cross-contamination when eating out
- Keep the food out of shared cooking areas
- Carry prescribed antihistamines or an adrenaline auto-injector
- Seek emergency help for any severe reaction
Sources & references
Allergy safety: what everyone should know
Mild-to-moderate reaction signs
- Itching, hives or a raised rash
- Swelling of lips, face or eyes
- Tingling mouth, sneezing, runny nose
- Stomach pain, nausea or vomiting
Anaphylaxis — call 999 (UK) or 112 (EU) immediately
- Difficult or noisy breathing, wheeze, persistent cough
- Swelling of the tongue or tightness in the throat
- Dizziness, collapse, pale and floppy (young children)
- Use an adrenaline auto-injector (e.g. EpiPen) at once if prescribed, then call an ambulance even if symptoms improve
Allergy or intolerance? A true allergy involves the immune system and can escalate quickly; an intolerance (e.g. lactose intolerance) is unpleasant but not life-threatening. The symptoms overlap, so self-diagnosis is unreliable.
Getting tested: home-testing kits based on IgG are not diagnostically valid. If you suspect an allergy, ask a GP for referral to an allergy clinic for skin-prick or specific-IgE testing and a supervised food challenge where appropriate.