Although most markers are harmless, there are others that contain methyl isobutyl ketone. This chemical irritates the nose and eyes and other symptoms such as headaches, dizziness, vomiting, and weakness.  Avoid using any marker on your skin as it can cause severe symptoms. In case you get some markings on your skin, you can use rubbing alcohol.  Afterward, wash your skin with soap and warm water to remove any chemical residue.