Why isn't my medication working?

I have been using allergy medicine for months now and it's just not working i even switched to a different one to see and this ones not working either? Sinus problems run in my family and that's why im sensitive to pollen and other environmental allergens. I am so depressed and sick of these allergies they ruined my summer last year and it seems they will ruin it again this year...
Why isn't my medication working?
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