what does an allergy do to you
If you have an allergy, your immune system acts as if the allergen were dangerous, releasing a chemical called histamine that causes allergy symptoms.Learn about headaches, a common symptom of allergies.If the allergen is something you breathe in from the air, your reaction will most likely affect your eyes, nose and lungs. If it's something you eat, it may affect your mouth, stomach and intestines. Food allergies also can cause skin rashes or even asthma symptoms.Food Allergy.f you have an allergy, your immune system acts as if the allergen were dangerous, releasing a chemical called histamine that causes allergy symptoms.