Treat early. The best time to treat fall allergy symptoms is before they start. The most effective treatment for allergic rhinitis is the prescription nasal cortisone sprays such as qnasl, nasonex, (mometasone) flonase, etc. Nasonex (mometasone) is approved to age 2 years old. Antihistamines can also be helpful. If symptoms not controlled, an allergist can be a great source of information and advice.
Avoid pollens. Fall allergies are usually due to pollens that are in the air at that time of year. Some people are allergic to molds and other substances that are on fallen, composting leaves. One can wear a mask when working outdoors or when hiking. Avoid playing outdoors when the pollen or smog levels are high. Medicines such as Claritin otc, zyrtec otc, or prescription nasal steroid sprays are helpful.