Incense can irritate the lungs due to the smoke that is produced when it is burned. Inhaling the smoke can cause irritation to the airways, resulting in coughing, wheezing, and chest tightness. Long-term exposure to incense smoke can also lead to an increased risk of respiratory illnesses, such as asthma and bronchitis. It is recommended to use incense in well-ventilated areas and to avoid burning it directly in front of your face.