Does mayonnaise contain mustard?

Many mayonnaises do, especially French-style and bought-in versions. Check the label or recipe.

Is mustard oil an allergen?

Yes. Mustard oil is a mustard product and must be declared under Annex II.

Do small amounts of mustard need to be declared?

Yes. Any Annex II allergen present in the finished food must be declared, regardless of quantity.

Do curry powders contain mustard?

Many do. Mustard seed is common in curry powders and in Indian tempering, so check the label.

Are mustard greens an allergen?

Mustard leaves and greens are part of the mustard plant and are covered by 'mustard and products thereof'. Declare them when they are used, for example in salads or stir-fries.

Mustard allergy: hidden mustard in dressings, marinades and spice blends

By the Menulta editorial team · Facts checked 15 October 2026 · Updated 15 October 2026

The short answer

A mustard allergy is an immune reaction to proteins in mustard seeds and products made from them. It is particularly well recognised in France, where mustard is widely eaten, and can cause severe reactions including anaphylaxis. Mustard is one of the 14 EU allergens. It hides in vinaigrettes, mayonnaise, sauces, marinades, glazes, sausages, pickles, curry powders and spice blends, often in small amounts that are easy to overlook.

What counts as mustard

Annex II lists 'mustard and products thereof' with no exemptions. That covers yellow, brown and black mustard seeds, ground mustard, prepared mustards, mustard oil, mustard flour and mustard greens and leaves. Some people with mustard allergy also react to other plants in the same family, such as rapeseed, but those are not Annex II allergens.

Where mustard hides

Hidden mustard in restaurant food
Component	Mustard source
Vinaigrettes and salad dressings	Dijon mustard as an emulsifier
Mayonnaise, aioli and tartare sauce	Mustard often added for stability and flavour
Marinades and glazes	Honey-mustard, mustard rubs for pork and chicken
Sauces	Cheese sauces, cream sauces, some barbecue sauces
Burgers, hot dogs and sandwiches	Condiments and relishes
Sausages and processed meats	Mustard seed or flour in the seasoning
Curries and Indian dishes	Mustard seeds in tempering and mustard oil
Pickles, chutneys, piccalilli	Mustard seed and turmeric-mustard bases
Spice blends and rubs	Ground mustard in many blends

Small amounts, big consequences

Mustard is often used in very small quantities: a teaspoon in a litre of dressing, a pinch in a spice rub. Cooks may not think of it as a meaningful ingredient, and it disappears into the finished sauce. But Article 9(1)(c) of Regulation 1169/2011 requires any Annex II allergen present in the finished food to be declared, whatever the amount. A house vinaigrette used across every salad can put mustard into a dozen dishes.

The same applies to bought-in mayonnaise and dressings. Many contain mustard, and supplier changes can add it without warning.

Mustard at the burger grill and sandwich station

Burger and sandwich stations are high-risk for mustard cross-contact. Squeeze bottles, spreading knives and shared toasting surfaces transfer condiments between orders. For a mustard-allergic guest, use clean utensils and a clean surface, check bread and bun labels, and leave sauces off unless they have been checked. Bought-in burger sauces are frequently mustard-based.

Making sure mustard is declared

List every house dressing, sauce and marinade as its own recipe in the allergen record, then link it to each dish that uses it. That way a single dressing containing mustard is automatically flagged everywhere it appears. Check spice blends and curry pastes, which often contain mustard seed, and review the record whenever a supplier changes.

Mustard in sauces made in advance

Many kitchens prepare dressings, marinades and sauces in large batches at the start of the week, then use them across many dishes. If a batch recipe changes, for example a chef adds Dijon to a dressing for better emulsion, every dish that uses that dressing gains mustard. The allergen record must change at the same moment, and staff must be told.

Label each batch container with its allergens and the date. That simple step lets anyone in the kitchen see at a glance whether a sauce contains mustard, without having to remember the recipe.

Questions to ask suppliers about mustard

Ask suppliers whether mayonnaise, dressings, burger sauces, barbecue sauces, relishes, chutneys, curry pastes and spice blends contain mustard, mustard seed, mustard flour or mustard oil. Ask sausage and processed meat suppliers about mustard in seasonings. Ask bread suppliers whether any rolls or buns are glazed or flavoured with mustard. Keep the answers with your allergen record and repeat the questions when a product changes.

Mustard is especially common in French, British, German and Indian food, so menus drawing on those cuisines need particular care.

Serving a guest with a mustard allergy

Check every component of the dish, including dressings and sauces made in advance. Offer the dish without dressing, or with plain olive oil and lemon, if the house dressing contains mustard. Use clean utensils at the grill and sandwich station, and confirm that bread and buns are mustard-free. If several components contain mustard, recommend a different dish rather than adapting it during service.

Sources

This guide is general information, not medical or legal advice. Guests with an allergy should follow their doctor's advice. Operators should confirm their own setup with their food safety adviser or local authority.