The most common cause of a black eye is a blow to the eye, forehead, or nose. Depending on where the blow lands, one or both eyes may be affected.
A blow to the nose often causes both eyes to swell because the swelling from the nasal injury causes fluid to collect in the loose tissues of the eyelids.
Surgical procedures to the face, such as a facelift, jaw surgery, or nose surgery, can cause black eyes.
A certain type of head injury, called a basilar skull fracture, causes both eyes to swell and blacken. This condition is typically described as "raccoon's eyes."
Other causes of swelling around the eye include allergic reactions, insect bites, cellulitis (skin infection around the eye), angioedema (a hereditary condition causing swelling, usually around both eyes), and dental infections. However, these conditions do not make the skin turn black and blue around the eye.