The most common cause of a bruised toenail is trauma to the toe itself. While the toenail cannot actually become bruised since it is composed of dead tissues, the skin underneath can become darkened and bruised when blunt force is applied to the toe over the nail bed. Less severe injury can also cause a bruised toenail. These injuries can include consistent rubbing from ill-fitting shoes, or repetitive force applied to the toe, such as during a soccer game.
A bruised toenail is generally always caused by some type of injury to the toe itself. Symptoms usually include discoloration and sometimes pain in the affected area. Pain may be severe and acute or it may present itself as a dull ache. When pain is minor or not present at all, treatment is not usually needed aside from refraining from engaging in activities that may present the risk of further injury.
In very severe cases where the nail bed is badly bruised, the toenail may fall off. It is not a good idea to remove a toenail, but if it becomes loose and starts to come off on its own, nothing should be done to prevent this. A new toenail will eventually grow in its place, although this generally takes several months. In the meantime, the area should be kept clean and the nail bed should be kept protected with bandages or a dressing.
Sometimes the bruised toenail will not fall off right away. In these cases, the bruising will either heal on its own if given enough time, or a new toenail will grow in and slowly replace the damaged area. The same rules for keeping the area clean and protected will apply in this case.
Although most of the time, bruising on or below the toenail will be related to force applied to the toe, sometimes other injuries can also cause this. Frostbite, for instance, can lead to discoloration similar to bruising below the toenail. This is a potentially serious condition which can lead to irreversible skin damage. Sometimes a sharp object may find its way beneath the nail bed and cause an open wound which may also bruise. Any open would should be cleaned thoroughly to prevent infection.
Anyone with a severely blackened toenail, or with the nail falling off, should contact a doctor immediately. He or she can make a proper assessment of the injury and give further instructions for treatment. Toenail infections may have to be treated with prescription antibiotics.