Mustard allergy
Mustard allergy, a labelled allergen in some regions.
About mustard allergy
Mustard is made from the seeds of the mustard plant and appears as table mustard, powder, seeds and, importantly, as a hidden ingredient in sauces, dressings, marinades, mayonnaise and processed foods. It is a recognised allergen that must be declared on food labels in the UK and EU, reflecting that it can cause serious reactions. Mustard allergy is IgE-mediated: the immune system makes antibodies to mustard seed proteins, which are stable, and eating even small amounts triggers a release of histamine and other chemicals.
Reactions usually begin quickly, within minutes, and can be severe, including anaphylaxis. Symptoms range from an itchy mouth, hives and swelling to vomiting, wheeze, throat tightness and collapse. Because mustard is part of the brassica family, some people show cross-reactivity with related plants such as rapeseed, and there can be links with certain other foods and, in some individuals, mugwort pollen. Its widespread hidden use makes accidental exposure a particular risk, so vigilance with labels is essential.
Diagnosis is based on your history with skin-prick or specific-IgE testing, and sometimes a supervised food challenge. Management means strict avoidance and careful label-reading, since mustard flour and seeds turn up in unexpected places such as sausages, curries, salad dressings and ready meals; because it is a named allergen, UK packaged foods must declare it. Anyone at risk of anaphylaxis should carry an adrenaline auto-injector. A severe reaction is a medical emergency: use the injector and call 999.
Common triggers
- Mustard and mustard seed\nSalad dressings and sauces\nMarinades and pickles
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.