When it comes to food allergies, most countries will use the adopted system of referring to what is called the "Big 8" food groups that cause allergies. One of these categories would include seafood like crabs, lobsters and shrimp. This is a relatively common allergy found worldwide and it is believed that around 2 percent of the population is currently suffering from this condition. The prevalence of the disease is much higher in areas close to the coast where more people have contact with this type of food.
When it comes to this specific allergy, there are various types of presentations of the disease that can vary based on the types of food that you have eaten. Most people will be more reactive to seafood either coming from the crustacean family or from the mollusk family. These symptoms will typically present in the first 2 hours after eating the food and will almost always involve multiple organ systems. Patients with this type of allergy will experience shortness of breath and rashes during the initial phase of the reaction. They may also have an increase in their heart rate and a drop in blood pressure depending on how sensitive they are to particular allergens.
If you are lucky, you may be able to eat specific types of seafood. The ability for you to do this lies within your DNA and some people have partial concentrations of enzymes capable of digestive these compounds found in seafood.
If you notice this type of reaction when first eating seafood, it is important for you to be able to pinpoint what exactly is causing these symptoms. A trip to an allergist is in order to determine what foods actually cause the disease. It is important for you to have a complete understanding of the foods that you are potentially allergic to for your own safety. In this controlled environment, the doctors will be able to give you specific tests to determine what types of foods you are allergic to and also note what concentrations of the substance you were given in order to be able to predict your response should you ingest the real food.
If these tests are inconclusive, a more direct but radical approach that we can do in a clinic would be to give you a piece of that specific food to see your reaction. You will have a nurse standing by your side ready to give you any therapy that you may need should a strong reaction occur but this is highly unlikely.
Because this is a condition that you will not outgrow, it is in your best interest to make sure you are adequately prepared with proper medications should a reaction occur unexpectedly. Make a habit out of carrying drugs like Benadryl or similar anti-histamine medication in order to help reduce the inflammatory response. An Epi-pen is also a useful purchase if you have a strong reaction to foods you have eaten accidentally. The most important thing is to become familiar with foods you are allergic to and do your best to avoid eating these types of foods, no matter how appetizing they may look. 
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