What is responsible for this urticarial reaction?

A 63-year-old woman believes that her hives of 1 day’s duration were brought on by something she ate.

Which specific food(s) do you query the patient about?

A. Alcohol.

B. Tomatoes.

C. Shellfish.

D. Nuts.

E. Chocolate.

F. Strawberries.

Answer: Urticarial reaction

All of the choices could have triggered the urticarial reaction; questioning revealed that this patient’s hives were precipitated by eating shrimp, C. This was confirmed 1 month later when she was rechallenged by inadvertently eating a shrimp dip. Both the initial and subsequent reactions cleared following a course of antihistamines. The patient was advised to avoid eating shellfish in the future.