Why do my allergy of seafood,foods only occur when i have a fever? but without my fever, i can eat seafoods-?

Your allergy is very slight. So when you are healthy, your immune system doesn't "wake up" and attack the seafood because it doesn't recognize it as something your body doesn't like. However, a fever is a side effect of your immune system "waking up" and working. If you have a cold or the flu or an infection, your body start producing all these defense forces to fight off the illness, and since it is awake it will more readily "notice" the seafood as something it doesn't like and attack that too. The hives are a side effect of histamines, little soldier-hormones that go and attack whatever is hurting your body. When this happens take an antihistamine, such as benadryl or a nighttime cold medicine (the antihistamine the the ingredient that makes you sleepy). It will relieve the symptoms. I will warn you though, since you have a known allergy you may want to talk to your doctor about getting an epipen or other emergency medication to have on you if you do end up (on purpose or by accident) eating sea food. Though your allergy is only slight now, it can get worse with time, and seafood allergies are notoriously deadly.

Think about it like this: A fever is a sign that your body is fighting off invaders. It sounds like your body has a difficult time handling seafood, but the body is an amazing mechanism, and when everything is working properly, you can't even tell that it doesn't like the seafood because you have enough internal fighting power to handle it. But, when your body is preoccupied with fighting off whatever it was fighting off that caused the fever, it does not have enough resources to also handle to seafood. This does not mean that you are allergic to seafood and can never eat it again. Most likely, you just have digestive issues that is causing your body to dislike the seafood.

Allergies and fever are immune reactions. Maybe when you have a fever your immune system is in high gear, so it reacts more readily to allergens?

Think about it like this: A fever is a sign that your body is fighting off invaders. It sounds like your body has a difficult time handling seafood, but the body is an amazing mechanism, and when everything is working properly, you can't even tell that it doesn't like the seafood because you have enough internal fighting power to handle it. But, when your body is preoccupied with fighting off whatever it was fighting off that caused the fever, it does not have enough resources to also handle to seafood. This does not mean that you are allergic to seafood and can never eat it again. Most likely, you just have digestive issues that is causing your body to dislike the seafood.

Allergies and fever are immune reactions. Maybe when you have a fever your immune system is in high gear, so it reacts more readily to allergens?