Allergies Due to Seasonal Changes?

[Andromeda18_]

Until I was about 10 years old I was allergic to chocolate. I cured it by eating tons and tons of chocolate which is something I can't resist. I was also allergic to cats and dogs when I was little but I had so many dogs back then (I had more than 30 at the same time once) that it also disappeared.
Nowadays I have no allergies at all. I have a friend who unfortunatly is allergic to just about everything. Last year she had to do a treatment which involved taking shots every week! Poor girl!