Why do I suffer from hay fever now, & have never done so in the past?

This can be attributed to a medical syndrome that has been termed ‘The Allergic March.’ This is a progression from early childhood through adulthood of a series of what can be seen as allergic states. For example, as a young child you might suffer from food allergies. As you get a little older, these food allergies tend to clear up and make way for asthma. Asthma tends to settle down in late teenage years and this is when hay fever usually begins to set in. Once you reach approximately 40 years old, the hay fever will all but disappear and the asthma may return.

Another explanation involves the gradual build up of IgE in the body to a specific hay fever causing agent (such as pollens and moulds). It might be that it takes the immune system a prolonged length of time to become sensitive to a particular trigger and this is when the symptoms of hay fever will begin. Or, it might be that your exposure to a particular allergen is at such a low level that the immune system only gradually becomes alert to it as a possible threat to the body.

Where you live can also play a role in your exposure to various hay fever allergens. It might be that you lived for many years in one part of the world that did not contain any pollens or moulds that caused an allergic reaction to be prompted by the immune system. Upon moving to a different location, however, exposure to the local flora and fauna might cause a hypersensitivity reaction to take place and kick start the immune system into launching a full on allergic reaction.