Test and treat. Find out what are his allergens by a blood or skin test. Then, you may be able to reduce exposure with this knowledge. See your ENT or general allergist to select medications for allergy. For some, allergy shots may be a great option to make him less allergic naturally.
Avoidance; medicine. Allergic rhinitis is usually due to pollens in the air. Some people are allergic to molds and other substances. 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, prescription antihistamine eye drops or singulair, (montelukast) and nasal steroid sprays are helpful. Allergy shots are another option.