This is also interesting, regarding additives.
http://nac.allergyforum.com/allergy/index.html

Allergic rhinitis, commonly called hay fever, is an allergy characterized by sneezing, itchy and watery eyes, a runny nose and a burning sensation of the palate and throat. Hay fever is usually caused by allergies to airborne substances such as dust, moulds, pollens, animal fur and feathers.
It is often aggravated by a food allergy, the most common being an allergy to milk.