I am allergic to milk casein, can i have whey?

In theory, yes.: If you have anaphylactic allergy to casein i'd steer clear of whey because you can't be certain that it's 100% free of casein. And if some whey products are, others may not be. So its russian roulette. Incidentally, tuna fish packed in water is routinely packed in a little cow's milk, watch out. Tuna packed in oil is safe. 92% of cow' milk allergic persons are also allergic to goat's milk.

Probably not...: Cow's milk contains casein (alphas1-, alphas2-, beta-, and kappa-caseins) & whey (alpha-lactalbumin, ala; beta-lactoglobulin, blg; bovine lactoferrin; bovine serum albumin, bsa; and bovine immunoglobulins). Acute allergic responses to milk are due to ige directed against various allergens in milk. All milk proteins are potential allergens & polysensitization to several proteins occurs in most pts.