Mustard is one of the most common spice allergiesTrusted Source. The primary allergen in yellow mustard is “Sin a 1.” The enzymes don’t break down much in the digestive tract, and the allergen is present even if the mustard is cooked in food. The major allergen in brown mustard is “Bra j 1.”
Anyone can develop a mustard allergy. It’s most common in the United Kingdom, Canada, and India — the countries that use the spice the most.
Many people with mustard allergies are also allergic to rapeseed. Some are also allergic to other products in the Brassicaceae family, including broccoli, cabbage, Brussels sprouts, cauliflower, turnips, and canola.