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Allergies result in many different symptoms such as sneezing, runny nose, itchy eyes, coughing, rashes, swelling of the face, stomach pain, vomiting, dry skin, anaphylaxis, etc.

An allergen can cause different symptoms for different people who are allergic to it... and different allergens can cause completely different symptoms for the same person. What characteristics of an allergen and/or the person determine what symptoms will arise?

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