Applying 100 percent tea tree oil solution to affected toenails with a Q-tip or cloth twice a day for six months cures toenail fungus in about 18 percent of patients and improves symptoms in about 60 percent of patients. This is about as effective as clotrimazole, according to WebMD.
Using less than 100 percent of a tea tree oil solution does not provide the same healing for toenail fungus. Tea tree oil can cause skin irritation and inflammation; placing a barrier layer of petroleum jelly on the toe around the affected nail is a solution if this becomes a problem, notes WebMD.
Although generally safe, tea tree is not recommended for boys who have not yet reached puberty. Tea tree oil can cause hormonal effects that may disrupt the normal progression of hormones. Some cases have ended with boys growing abnormal tissue in the breast area, a condition known as gynecomastia. Young boys with toenail fungus should use a different treatment, advises WebMD.
Tea tree oil and other essential oils should never be ingested orally because of a number of serious side effects, such as confusion, unsteadiness, loss of ability to walk, skin rash and coma, as stated by WebMD.