Seasonal allergies – ahchoo! – also known as allergic rhinitis or hay fever – ahchoo! – affect more than one in five people, according to the Mayo Clinic. They are an annoyance that can reduce quality of life by – ahchoo! – rudely interrupting your day-to-day routine. However, some seasonal allergies are more serious than that and can cause severe allergic reactions in some people. One of the best ways to avoid this issue is to know the common causes of spring and summer allergies.