Fish Allergy

Fish allergy is one of the 14 major allergens in the UK. All finned fish — like cod, haddock, salmon and tuna — can trigger reactions. If you react to one type, it’s common to react to others too.

Overview

Fish allergy occurs when the immune system mistakes fish proteins as harmful and releases chemicals like histamine. This usually causes symptoms within minutes of eating fish. Unlike shellfish, which are crustaceans or molluscs, fish allergy refers to species with fins and gills.

Symptoms

Mild to moderate symptoms may include:

• Itchy rash (hives)
• Tingling or itching in the mouth
• Swelling of lips, face or eyes
• Tummy pain or vomiting

Severe reaction (anaphylaxis) may include:

• Airway: swelling in the throat or tongue, difficulty swallowing
• Breathing: wheeze, shortness of breath, noisy breathing
• Circulation: dizziness, faintness, pale clammy skin, confusion, collapse

Who is at higher risk?

• A previous serious reaction
• Asthma, especially if not well controlled
• Reactions to tiny amounts of fish

Treatment

Mild symptoms may be treated with oral antihistamines. If you’re at risk of anaphylaxis, you should carry two prescribed adrenaline auto‑injectors (such as EpiPen® or Jext®) and know how to use them. In an emergency, call 999.

Avoiding fish

Most people with a fish allergy are advised to avoid all types of fish, as the proteins are similar and cross‑contamination is common. Read labels carefully — by law, fish must be highlighted in ingredients lists. Take extra care at fish counters, markets, or when eating out.

Useful links

• NHS — Food allergy
• Allergy UK
• BSACI — Find an allergy clinic