The best way to fight a case of toenail fungus is to begin applying a nail fungus treatment as soon as you detect the infection. The longer you wait to start treatment, the more time it give the dermatophytes (fungal agents that cause nail fungus) to dig in, multiply and spread. However, a person needs to understand what the primary symptoms of nail fungus are in order to detect the infection in its earliest stages. So, the remainder of this post is a list of common symptoms that indicate the presence of a nail fungus infection.