Apply tea tree oil externally on top of the skin, advises About.com. Diluting the oil with water before application lessens the possibility of skin irritation.
To properly dilute this natural substance, use five parts tea tree oil to 95 parts water, as stated on About.com. Apply the mixture with a cotton ball, and place it directly onto the blemish or affected area.
Tea tree oil effectively treats acne, athlete's foot, cold sores and dandruff, explains the National Center for Complementary and Integrative Health. Possible side effects include itching or blistering at the sight of application. Do not swallow tea tree oil, as it is considered poisonous if ingested.