Prior to Lamisil there was little or no hope for those that had a type of nail fungus called onychomycosis. The problem is that this fungus lives under your nail in what is called the nail bed. Surface treatments are just not able to reach that deep and in adequate amounts to kill the fungus. Lamisil attacks this fungus at a different level using the bloodstream to get to where the infection actually lives making it easier to destroy. The nail fungus is attracted to keratin which is a substance in your nails and skin. The active ingredient in Lamisil is also attracted to keratin. Once Lamisil gets to the source it will stay under your nail for a couple months even after you have quit taking the medication. Lamisil does have some side effects. Typically they go unnoticed but you should be aware of them. A strong medication like Lamisil requires scheduled checkups on how your body is reacting to the medication.