Subungual hematoma

A subungual hematoma is a collection of blood (hematoma) underneath a toenail or fingernail. It can be extremely painful for an injury of its size, although otherwise it is not a serious medical condition. A laceration of the nail bed causes bleeding into the constricted area underneath the hard nail plate. The blood pools under the nail, giving a reddish, brownish, blueish, or grey/blackish discoloration. The blood puts pressure to the nailbed causing pain which can be throbbing in quality and disappears when the pressure on the nail bed is relieved. Subungual hematomas typically heal without incident, though infection may occur. The pressure of the blood blister may cause separation of nail plate from the nail bed (onycholysis), but the nail should not be pulled off, as this can cause scarring of the nailbed and deformed nails. Nail discolouration may last some months. The nail plate may also become thicker and more brittle as a result of the injury (onychochauxis). The deformed nail plate will gradually grow out and be replaced by new, normal-appearing nail plate in several months' time. Infrequently, the nail may become painful and require surgical drainage. The condition is caused by a traumatic injury, such as slamming a finger in a door, or from sports activities, especially those involving sudden accelerations, such as soccer, basketball, and tennis, or going downhill, such as running or hiking rugged terrain, and ill-fitting footwear. Repeatedly thrusting the toes against a shoe's toe box can cause a subungual hematoma called jogger's toe, runner's toe, or black toenail. In a marathon, several percent of runners may be affected. Wearing footwear which fits helps prevent runner's toe. If the shoe is too loose on the midfoot, the foot can slide forwards in the shoe, especially when going downhill. This may jam the toes into the end of the toebox. If the foot is sliding forwards because the shoe is too loose around the midfoot, it may be restrained by lacing the shoe carefully, or placing bulky padding between the tongue and the lacing, or by wrapping a strap in a figure-eight around the foot and ankle ().