Shrimp / prawn allergy
Crustacean allergy to shrimp and prawns.
About shrimp / prawn allergy
Shrimp and prawns are crustaceans and among the most frequent triggers of shellfish allergy, which often begins in adolescence or adulthood and tends to last for life. The reaction is IgE-mediated, with the immune system producing antibodies to muscle proteins, principally tropomyosin, that prompt a rapid release of histamine and other chemicals when the shellfish is eaten. Tropomyosin is heat-stable, so cooked shrimp and prawns are as capable of triggering reactions as raw ones.
Symptoms usually appear within minutes and may include an itchy mouth, hives, swelling, vomiting, wheeze and anaphylaxis with breathing difficulty or collapse. Because tropomyosin is shared, people allergic to shrimp or prawn commonly react to other crustaceans such as crab and lobster, and sometimes to molluscs; the same protein family explains why some people also react to house dust mite. Even the steam from cooking can affect very sensitive individuals.
Diagnosis uses skin-prick or specific-IgE blood tests, sometimes with component testing or a supervised challenge. Management depends on strict avoidance, careful checking of dishes, sauces, stocks and processed foods, and awareness of cross-contamination in kitchens and seafood restaurants. People at risk of severe reactions carry an adrenaline auto-injector and an action plan. A severe reaction is a medical emergency: give adrenaline at once and call 999.
Common triggers
- Shrimp / prawn 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.