Various other chemical agents, such as preservatives, are often added to fresh fish or shrimp / prawn cocktails, and can be the cause of allergic symptoms
in individuals who are not allergic to fish
or crayfish.So it is better to undergo allergy testing to find out to which allergens you are allergic.
Lastly,Telfast is a non sedating antihistaminic, fexofenadine.It is used to treat hives ,itching and other symptoms of allergies and hay fever.
Hope it helps.