Incense is a material that creates a smell when it is burned. Incense overdose can occur when someone accidentally or intentionally sniffs or swallows liquid incense. Solid incense is not considered poisonous.
Liquid incense is sold on the Internet under a variety of brand names. It is usually described as a room deodorizer, despite being sold for other purposes. Liquid incense that is breathed in (inhaled) is called a "popper."