If you suspect an allergy to mustard, you can take a blood test that measures the level of your IgE antibodies (immunoglobulin E) in the blood.
In case of elevated or high levels of IgE antibodies in the blood, it may indicate an allergy to mustard.
This test measures allergens specifically for mustard, which is recommended if you have strong suspicions that it is mustard in particular that you are allergic to.
It is important to note that an allergy to mustard cannot be 100% determined with a blood test. Therefore, contact the healthcare provider who can help you further with investigation based on your possible test results.