Household plants can cause skin rashes and itching of the eyes.

The most well-known cause of inhalation allergies is the ficus benjamina. The ficus leaves' "milk" contains allergens which are then inhaled with dust particles contaminated with the plant milk. The allergens also end up on floors, clothing, and furniture, and are hard to get rid of.

The most common pollen allergies (grass, birch) are a seasonal problem. Cut flowers, blooming branches (like those for the easter tree) and even dried flowers or grasses can cause problems year-round. Pollen often remains in the house even after a thorough cleaning.