Your symptoms point toward environmental allergies or airway sensitivity, which started prior to your radioiodine ablation (RAI). For safe relief, you can use non-drowsy generic antihistamines like cetirizine or loratadine to target both the watery eyes and cough. Preservative-free artificial tears can also soothe eye irritation. If you have a dry cough, a simple cough suppressant like dextromethorphan is generally safe. Avoid cough medications containing iodine. Since you recently had RAI, please consult your endocrinologist or primary doctor before starting new medications, to ensure they do not interfere with your recovery or thyroid hormone management.