Discolored toenails can be treated with oral anti-fungal medications or topical anti-fungal medications, says WebMD. In some cases, surgical removal of the infected toenail followed by direct application of topical anti-fungal medication to the nail bed is necessary to clear up the condition.
Oral anti-fungal medications such as terbinefine can clear up a fungal infection that is causing discolored toenails in approximately 50% of people, according to WebMD.
In practically all cases of discolored toenails, the cause is a fungal infection, says Medicine.net. Other causes include trauma to the toenail causing bleeding underneath the nail, a bacterial infection underneath the nail, or excessive use of nail polish. These conditions are generally self-limiting and clear up on their own with no treatment.