Clean the nail without necessarily filing it and remove all traces of nail polish before each use.
Apply the solution twice a day for the first four weeks, then once a day until a healthy nail replaces the affected one. Apply to the entire surface of the nail, including under the tip.
Make sure to close the pen securely after each use.
After application, avoid exposing the treated areas to sunlight. Wait several hours before washing them.
For external use only.