Spa composition with tea tree oil on blue wooden background

Essential oils are becoming increasingly popular as people learn about the benefits of using natural remedies to alleviate symptoms. But while tea tree oil may be effective, it's important to understand that just because something is natural doesn't mean it won't have negative side effects.

Tea tree oil is one of the most well-tolerated oils out there, but there's a possibility of having a reaction to it, especially if you have, or develop, a tea tree oil allergy. When using tea tree oil, you can reduce your risk of experiencing side effects by following proper dilution and usage recommendations.

Tea Tree Oil Uses

Tea tree oil, which is also called Melaleuca oil, is extracted from the Australian tea tree. However, like all essential oils, tea tree oil is 50 to 100 times more concentrated than the actual plant, and this is where it gets its health properties.

Because it can kill bacteria and fungi, tea tree oil is classified as antimicrobial and antiseptic, and it's used for a variety of conditions that are caused by invasive microbes (or have the potential to become infected by them). Some of the most common tea tree oil uses include:

  • Athlete's foot
  • Acne
  • Dandruff
  • Lice
  • Yeast infections
  • Minor cuts and burns

Michigan Medicine also notes that some people use tea tree oil in a vaporizer or as part of a steam bath to clear up lung problems and respiratory issues associated with mucus and congestion.

Tea Tree Oil Side Effects

While there are many tea tree oil benefits when used correctly, it's possible to experience negative side effects. Most of them are mild and affect the skin only in the area where the oil was applied. The Mayo Clinic notes that the ones most commonly reported are:

  • Skin rash (contact dermatitis)
  • Stinging
  • Burning
  • Itching
  • Dryness
  • Scaling
  • Redness

While most skin reactions are mild, tea tree oil is extremely toxic if swallowed. Ingestion of tea tree oil can lead to:

  • Confusion
  • A lack of muscle control
  • Loss of conciousness

The National Capital Poison Center, noting the extremely serious risks involved with ingesting the substance, emphasizes the importance of never swallowing tea tree oil.

The Possibility of Hormonal Disruption

There is another possible side effect that's worth mentioning, although there haven't been many reported cases of it (and the few reported cases on record are old). A February 2007 report in the New England Journal of Medicine listed a case of a 10-year-old boy who developed gynecomastia, which is defined as enlargement of the breast tissue in males due to hormonal disruptions.

Upon further investigation, the researchers pinpointed the cause: a hair shampoo and gel that contained tea tree oil and lavender oil. He was instructed to stop using the products and after nine months, the gynecomastia went away.

However, two other cases listed in the report involved boys experiencing disappearance of gynecomastia after they discontinued using products that resulted in the problem in the first place. Those products contained only lavender oil. So, it's possible that it was the lavender oil and not the tea tree oil that was the underlying cause of the 10-year-old boy's gynecomastia.

Read more: The Bad Side Effects of Lavender Oil That Get Overlooked

Sensitization to Tea Tree Oil

Sensitization is a word that's often used in the essential oil community, but many people aren't really sure what it means or how it develops. Sensitization is a type of tea tree oil allergy, but it develops over time and with repeated exposure to the same oil. In other words, your skin is OK with the oil at first, but after repeated exposure, it starts to develop a sensitivity to it.

A sensitization reaction can be immediate or delayed. Immediate reactions show up as soon as you put the oil on your skin, while delayed reactions can show up hours later. Delayed reactions also tend to get progressively worse with repeated exposure to the oil. Symptoms of both types of reactions are usually moderate to severe and may include:

  • Redness
  • Swelling
  • Blotchiness
  • Rash
  • Itchiness
  • Blistering
  • Chemical burn appearance
  • Pain

There's no way to know for sure whether you'll develop sensitization to tea tree oil or any other essential oil, but there are things that increase your risk:

  • Applying the oil to the skin undiluted (or "neat")
  • Not diluting the oil properly
  • Frequent use or overuse of the same oil
  • Applying oil to broken skin, open sores or wounds

It's also possible to be outright allergic to tea tree oil. If you already have an allergy, symptoms typically appear within five to 10 minutes of applying the essential oil. And, unlike sensitization, an allergy may affect other parts of the body, not just the area where the oil was applied.

If you have a true allergy or develop a sensitization to tea tree oil, you'll have to completely avoid that oil forever, but if you don't, there are some things that you can do to decrease your risk of becoming sensitive to it.

Dilute Tea Tree Oil Properly

The first rule of thumb to using tea tree oil (and all other essential oils) safely is that you must dilute it. Essential oils are highly concentrated, and putting them on your skin directly without any sort of barrier increases the risk of negative side effects and desensitization. Because tea tree oil is oil-based, it must be diluted with a fat-based oil, instead of something that's water-based. After all, oil and water don't mix.

You can dilute tea tree oil with any fat-rich oil, but some common choices are coconut oil, jojoba oil, almond oil and avocado oil. The oil in which you dilute the tea tree oil is referred to as a "carrier oil."

The ratio of carrier oil to essential oil depends on what you're using the tea tree oil for, but the concentration of your tea tree oil should never exceed 5 percent. This means that, if you have a standard 30-milliliter (or 1-ounce) bottle of a carrier oil, you can add a maximum of 45 drops of tea tree oil to the bottle.

Of course, this is a general safety guideline and you may need even less than that. Always talk to your doctor or work with a registered aromatherapist to figure out the best concentration for your condition.

Other Safety Precautions

You can also reduce your risk of experiencing tea tree oil side effects by minimizing your exposure or altering your usage. Instead of daily applying tea tree oil or products that contain it, follow a schedule of two weeks on and two weeks off as recommended by Aromatherapy United. In other words, apply the tea tree oil for two weeks, give your skin a break for two weeks, then go back to another two weeks of application if you need it.

You should also avoid applying tea tree oil to any open wounds or sores. Once the healing process has started and the wound is closed, you can use properly diluted tea tree oil on the affected area.