Complications can occur in 40% of hemangiomas, and complications vary depending on the location, size, and growth rate of the hemangioma. Complications can be functional or organic and commonly include ulceration, hemorrhage, infection, heart failure, impaired vision, airway obstruction, feeding difficulties, and obstruction of the external ear canal. Ulceration is the most common complication of hemangioma , followed by hemorrhage. Ulcers often occur during the growth period and are more likely to occur in friction-prone areas. Ulcers are painful, can be followed by infection and bleeding, and eventually heal with scarring. Bleeding is usually due to venous leakage from increased localized pressure, but systemic coagulation disorders or arteriovenous malformations need to be excluded. Infection is also a common complication of infantile hemangiomas. Infections are primary on the one hand, but more often secondary to ulceration, and are more likely to occur in difficult-to-care-for areas such as the mouth and perianal area. Mixed hemangiomas can lead to shunting of the great vessels, which can lead to high-output heart failure. Hemangiomas around the eyes can cause astigmatism, ptosis, strabismus, refractive error, proptosis, amblyopia, and blindness. Hemangiomas in the neck or lower part of the face may be associated with subglottic hemangiomas, causing airway obstruction, which can be severe enough to cause death. Hemangiomas in the mouth or nasal cavity can cause feeding difficulties. Hemangiomas of the ear can cause obstruction of the external auditory canal, which may affect hearing in the short term, but have little effect on hearing in the long term. Overgrowth of giant infantile hemangiomas of the face can invade the facial bones or ear cartilage.