The main cause of white spots on the nails is minor to moderate trauma to the nail, according to HowStuffWorks. Other causes of white spots on the nails include a fungus, allergy, minor infection or medication.
In almost all cases, the white spots on nails do not require treatment, nor should they be worrisome, explains HowStuffWorks. The white spots typically disappear as the nail grows out, and the spots should not occur again unless there is another trauma to the nail. If all nails show streaks or white spots, there may be a more serious cause, including anemia, cirrhosis, cardiac disease, kidney disease or diabetes. If there are changes or abnormalities that seem concerning, it is best for people to talk to a doctor.
White spots or streaks on the nail may also occur due to a fungus, which can be difficult to treat, states WebMD. Treatment often begins with antifungal medications, which come in cream, gel or nail polish form. Some of these are available over-the-counter, but other medications are only available by prescription. These topical antifungal medications usually work for mild nail fungus, but for moderate cases, an oral antifungal medication often works well. In the most severe cases, removal of the nail is usually the only cure.