Negative Effects of Tea Tree Oil

Tea tree oil contains antibacterial, antifungal and antiviral compounds called terpenes. According to Elena Conis of the "Los Angeles Times", it is used to treat acne, athlete's foot, dandruff, insect bites, jock itch and yeast infections reports. While preliminary research suggests that tea tree oil may be effective at treating acne, fungal infections and staph infections, no conclusive studies prove its effectiveness, points out Aetna Intelihealth. Furthermore, its possible negative effects and interactions have not been fully established. Possible adverse effects can include skin reactions from topical applications and serious side effects if taken internally.

Skin Effects

• Tea tree oil can cause dry skin and rashes.

  Topical use of tea tree oil can cause skin irritation and allergic reactions. Allergic contact eczema and dermatitis can occur, reports Drugs.com. Intelihealth says that allergic reactions can include itchy, red rashes and swelling skin. Negative effects are more likely to occur in people allergic to plants of the Myrtle family or those allergic to balsam of Peru.

Adverse Effects Orally

• Tea tree oil is toxic when ingested orally.

  Tea tree oil should never be ingested and you should avoid getting it your ears and eyes, warns Conis. Memorial Sloan-Kettering Cancer Center reports that oral ingestion of tea tree oil results in serious negative effects including body rash and abnormal blood counts. More serious adverse effects include confusion and disorientation, lack of muscle control and coma. Intelihealth adds depression, drowsiness, muscle tremors, muscle weakness and stomach upset to the list of negative side effects when tea tree oil is taken orally.

Interactions With Drugs and Herbs

• Interactions with other drugs and supplements haven't been sufficiently established.

  Tea tree oil hasn't been sufficiently studied to determine its interactions with other drugs and herbal supplements according to Drugs.com. Aetna Intelihealth reports that tea tree oil has the potential to intensify drying of the skin when combined with other acne medications and it may interact with antibiotics, antifungals, anti-inflammatory medications, cancer medications and insect repellents with negative side effects and poor results.

Gynecomastia

• Tea tree oil may cause breast enlargement in prepubescent males.

  Gynecomastia, breast development in boys, has occurred with topical use tea tree oil. Three prepubescent healthy boys developed gynecomastia after using lavender and tea tree oil products in a study published in the February, 2007 issue of "The New England Journal of Medicine." When use of the products was discontinued, the breast enlargement halted and reversed. The study's authors reported that tea tree oil has estrogenic effects and negative effects on male hormones when studied in the laboratory setting.