Hay fever, asthma, food allergies, and eczema are some common types of allergies. An allergy can produce several symptoms, such as sneezing, redness of the eyes, respiratory problems, hives, itching, bloating, diarrhea, and vomiting. Allergies are usually treated with antihistamine medicines, and topical, nasal, and oral corticosteroids. However, some herbs can also help reduce the frequency of allergic reactions by building up resistance against allergens.