Profile of symptoms depend entirely on what you are allergic. For example, if you are allergic to grass pollen, you have symptoms when large amounts of grass pollen in the air. Your symptoms will begin in late May and continue throughout the summer, gradually decreases towards the end of August. Similarly, if you are allergic to tree pollen or weed pollen, you have symptoms in spring and autumn respectively.
Although most of the people of the medical community will accept that they have no connection with this clue really causes Idiopathic Thrombopathic plasma (ITP), there are many astute doctors who have come to believe that the underlying causes of ITP are combination of negative environmental and genetic factors. This is complicated, that when exposed to the same environmental stimulus toxic, some people may develop cancer, while others may develop lupus or asthma and can still develop the disease ITP. Surely this is the kind of genetic predisposition or inherent weakness in the body.