Do seasonal allergies cause dizziness?

Possibly: Occasionally, dizziness and vertigo might happen in conjunction with seasonal allergies, but it is not likely unless the allergy symptoms are very prominent (i.e. Itching, watery eyes, running nose, itching nose and throat, sneezing, nasal congestion), and even then, it's not common. You should not assume that the dizziness is from allergies without an evaluation.

No...but: I agree with dr. Mcghee's answer. Dizziness can be caused by the medications you're taking to treat allergic rhinitis. Phenylephrine, the decongestant found in many over-the-counter & prescription oral medications for seasonal allergies can cause dizziness. If congestion is your main problem, topical antihistamine or corticosteroid sprays may be a better solution. They don't contain phenylephrine.