The season when your seasonal allergies peak can help you understand what allergens you react to. Here’s a quick list of the most common seasonal allergens, and when they're the most likely to cause allergic rhinitis:
- Tree pollen (spring) – Trees release their pollen first, usually in late winter and early spring. If your allergies peak around this time, you are likely allergic to one or more types of tree pollen.
- Grass pollen (summer) – In the late spring and throughout the summer, grass pollen is the most common allergen.
- Ragweed (fall) – Ragweed usually releases its pollen in the late summer and early fall, with levels peaking in September. Ragweed has particularly fine pollen, and a single plant can make up to one billion pollen grains, so this is a very common cause of seasonal allergies.
- Mold (fall) – Outdoor mold is a less common allergen. However, it also peaks in the early fall, so if you’re not allergic to ragweed but your allergies get worse in the fall, this may be the cause.
There are also lots of “perennial allergens” that can cause allergy symptoms all year round, even indoors. These include dust mite allergies, allergies to pet hair and dander, indoor mold allergies, and a number of others.