Tea tree oil is an effective natural remedy for nail fungus, according to WebMD. Traditionally used as an antifungal treatment, tea tree oil is a topical solution that kills toenail and fingernail fungus as well as other types of fungal infections.
An extract from an Australian plant, tea tree oil can only be used topically and should never be ingested, states WebMD. Tea tree oil is found in many topical creams and gels, which are used to treat conditions such as acne and athlete's foot, in varying strengths. Applying large amounts of tea tree oil to the skin can cause reactions such as blistering.