Mackerel allergy
Allergy to mackerel.
About mackerel allergy
Mackerel is an oily finned fish, and allergy to it is a form of fish allergy, which is common and often lifelong. The key allergen is parvalbumin, a muscle protein that is very stable and survives cooking, so fresh, smoked and cooked mackerel can all cause reactions. The allergy is IgE-mediated: the immune system produces antibodies to parvalbumin, and on later exposure these drive a fast release of histamine and other inflammatory chemicals. Because parvalbumin is shared across many species, fish-allergic people often react to more than one fish.
Reactions typically come on rapidly, often within minutes, and can be severe, including anaphylaxis. Symptoms range from hives, itching and facial swelling to vomiting, wheeze, throat tightness, a drop in blood pressure and collapse. Some highly sensitive people react to cooking steam or vapours. There is a separate issue to be aware of with mackerel and other oily fish called scombroid poisoning, caused by histamine forming in poorly stored fish; it mimics an allergic reaction but is actually food poisoning affecting anyone who eats the spoiled fish.
Diagnosis uses your history with skin-prick or specific-IgE testing, and sometimes a supervised challenge, and helps distinguish true allergy from scombroid poisoning. Management is avoidance of mackerel and usually other finned fish unless testing suggests otherwise, careful label-reading, and caution with stocks, sauces and shared fryers. Anyone at risk of anaphylaxis should carry an adrenaline auto-injector. A severe reaction is a medical emergency: call 999 immediately.
Common triggers
- Mackerel 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.