The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.
There are many reports of allergy to tea tree oil when taken by mouth or used on the skin. Skin reactions range from mild contact dermatitis to severe blistering rashes. People with a history of allergy to tea tree oil ( Melaleuca alternifolia ), to any of its components, or to plants that are members of the myrtle (Myrtaceae) family, balsam of Peru, or benzoin, should not use tea tree oil. Use cautiously if allergic to eucalyptol as many tea tree preparations contain eucalyptol.
Side Effects and Warnings
Tea tree oil taken by mouth has been associated with potentially severe reactions, even when used in small quantities. Several reports describe people using tea tree oil by mouth who developed severe rash, reduced immune system function, abdominal pain, diarrhea, lethargy, drowsiness, inflammation of the corners of the mouth, slow or uneven walking, confusion, or coma. There have also been reports of nausea, unpleasant taste, burning sensation, and bad breath associated with tea tree oil use. Many tea tree preparations contain large volumes of alcohol.
When used on the skin, tea tree oil may cause allergic rash, redness, blistering, and itching. This may be particularly severe in people with pre-existing skin conditions such as eczema. Use of tea tree oil inside of the mouth or eyes can cause irritation. Animal research suggests that tea tree oil used on the skin in large quantities can cause serious reactions such as difficulty walking, weakness, muscle tremor, slowing of brain function, and poor coordination. When applied in the ears of animals, 100% tea tree oil has caused reduced hearing, although a 2% solution has not led to lasting changes in hearing. The effect of tea tree oil on hearing when used in the ears of humans is not known.
Pregnancy and Breastfeeding
Not enough scientific information is available to recommend tea tree oil during pregnancy or breastfeeding. Animal studies suggest caution in the use of tea tree oil during childbirth because tea tree oil has been reported to decrease the force of spontaneous contractions, which theoretically could put the baby and mother at risk. Women who are breastfeeding should not apply tea tree oil to the breast or nipple since it may be absorbed by the infant.