Tea Tree Oil Side Effects

Tea tree oil, sometimes known as oil of melaleuca, is an essential oil derived by steam distillation of the Australian tea tree leaves. When used as a topical application, this oil is known for its antibacterial properties. It is generally used as a treatment for acne, insect bites, lice, nail fungus, athlete’s foot, and other fungal infections. Tea tree oil is present as an essential oil in numerous commercial skin care products like lotions, creams, and soaps. Even so, tea tree oil should never be taken internally. If ingested, it can lead to serious side effects. You should also read our Comprehensive Guide To Tree Tea Oil Uses and Benefits.

How Safe Is Tea Tree Oil?

Tea tree oil is known to cause harmful side effects if taken internally. While it is considered safe when applied topically, it could cause skin dryness, irritation, itching, and inflammation in some sensitive individuals. Although its natural components have been found to be beneficial, misuse of the oil could be unsafe. The bad effects of tea tree oil can be reduced if its ingestion is avoided, an Australian study reported.

Tea Tree Oil Side Effects

Below are known side effects that can occur when tea tree oil is used improperly.

Allergic Reactions

Individuals who are sensitive to tea tree oil can display varying allergic reactions ranging from slight skin irritation to acute rashes. While people who are not allergic to the oil can use it without much worry, you should use it with some amount of caution if you’re using tea tree oil for the first time. Dry or broken skin is more likely to develop skin irritation when the essential oil is applied. The known reactions include itching and burning sensation, itchiness, as well as moderate to severe swelling. For this reason, it is a smart thing to do a patch test on the skin before applying the oil. If you are sensitive to guava, eucalyptus or cloves, you have a tendency to experience tea tree oil side effects. Tea tree oil that has undergone the aging process has a higher probability to cause allergies. Also be wary of other allergic reactions that include dizziness, nausea, flushing, inflammation, diarrhea, muscle contractions, congestion, and anaphylaxis which can become deadly. One study claimed that although most side effects are brought about by the use of pure tea tree oil, the products that use the oil as an ingredient could also be blamed in some instances.

Scalp Issues

While tea tree oil is used as a treatment for scalp problems like dandruff, it seems a lot more study is required to confirm its benefits for the scalp. Some users claimed to have developed scalp allergies after using tea tree oil.

Impaired Sense of Taste

A study was conducted comparing mouthwashes, one containing a compound known as CPC (cetylpyridinium chloride), the other containing tea tree oil. The mouthwash that contained CPC proved better for gingivitis. Significantly, the mouthwash with tea tree oil as an ingredient had caused an impairment of the sense of taste. Most essential oils like tea tree oil, as published by the Vanderbilt University of Medical Center in a report, have a disagreeable bitter taste that causes children to choke when taken orally.

Hormonal Imbalance

Tea tree oil has been noted to cause abnormal breast growth in teenaged boys. The oil could have interfered with the endocrine function which resulted in gynecomastia (abnormal enlargement of breasts in men) due to impaired hormone function. The New England Journal of Medicine mentioned that the symptoms were diminished in most of the cases after the use of tea tree oil was stopped. The National Institutes of Health likewise reported similar discoveries.

Depression and Tiredness

Although it hasn’t been observed in human subjects yet, depression, fatigue, and related side effects have been recorded in cats and dogs after the application of tea tree oil in higher doses. The oil can cause extreme drowsiness as well if taken internally. Excessive weakness is one of its serious toxicity symptoms.

Nasal Problems

Even if tea tree oil is frequently used for treating nasal polyps, it also has its share of unwanted side effects. The oil was found to cause a runny nose and can sting or burn at times. The nasal polyp may become enlarged before it gets smaller.


Diarrhea has also been noted as one of tea tree oil’s unfavorable side effects. Cases of diarrhea and other allergic reactions were observed in users who have ingested tea tree oil when they shouldn’t have.

Mouth Inflammation

Using tea tree oil can lead to various side effects such as inflammation of the mouth, although no definite information is available. If some soreness occurs in your mouth, be sure to seek professional medical advice.

Ear Soreness

When tea tree oil is applied to the mucous membrane without diluting, the user might feel some swelling and pain. When used as a treatment for ear infection, it is highly recommended to mix it first with a carrier oil like olive or almond oil. Tea tree oil diluted with any of these carrier oils can be used in the ear canal for treating infections. A safe and better way to use tea tree oil is to add a few drops in one-fourth cup slightly heated olive oil. Tilt your head to one side and, with the aid of a dropper, put some drops of oil into the affected ear. Keep your head in a tilted position for a while so the oil can make its way through the ear canal. Observe proper care when you use tea tree oil at home to cure an ear infection. Better yet, seek your doctor’s recommendation before undergoing a DIY treatment. Some studies, however, have advised against the use of tea tree oil in the ear as it could cause internal damage.

Involuntary Trembling

Animal toxicologists found that cats and dogs treated to high doses of tea tree oil showed side effects that include uncontrollable trembling. While the animals were cured, there is speculation of similar effects in human beings.

High Risk for Pregnant or Lactating Women

Some studies have shown that using tea tree oil during labor can make the uterus to stop contractions, thereby putting both mother and newborn in harm’s way. Women should never take the oil internally when they are pregnant or lactating as they can pass on the oil’s toxic effects on their child.

Tea Tree Oil Safety Guidelines

If you think that it is alright to take the diluted form of tea tree oil orally, then get the thought out of your mind. Like what was mentioned before, this essential oil should never be taken through the mouth in any form or dilution because of its high toxicity. The American Cancer Society warns that ingesting tea tree oil can cause the above-mentioned side effects, as well as other more life-threatening side effects. These include hallucinations, ataxia (uncoordinated movement), blood cell abnormalities, and possibly coma. These are the tea tree oil side effects you need to be aware of. When used in the right and recommended manner, they can be considered safe in most cases. But taking it orally can lead to poisoning. For this reason, it pays to know what the dosage of this essential oil is safe for you. Always keep tea tree oil away from your children and pets.