One-sided nasal blockage for years is often due to a deviated septum, sinus issues, or nasal swelling, which can reduce airflow. Do steam inhalation, keep your nose moist, avoid dust and cold exposure, and stay hydrated to ease blockage. Sleep with your head slightly raised and maintain a clean environment to reduce irritation. If it has been long-lasting or is affecting breathing, consult a doctor to determine the cause and guide appropriate treatment.