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Tea tree oil is a type of essential oil that comes from the leaves of the Australian tea tree. It has several health-related benefits, including antimicrobial and anti-inflammatory activities.

Tea tree oil can be used to help treat a variety of conditions, particularly issues related to the skin. It can also be found as an ingredient in some cosmetic and cleaning products.

Even though tea tree oil is generally well tolerated, there are some potential side effects to know about. Continue reading as we explore tea tree oil, its side effects, and how to use it safely.

Research into the benefits of tea tree oil is ongoing. Based on what’s currently known about tea tree oil, it’s sometimes used as a natural treatment for certain health conditions, such as:

Tea tree oil is also used in many cosmetic products, such as shampoos, lotions, and soaps. Additionally, it can be included as an ingredient in some household cleaning products.

The possible side effects of tea tree oil depend on how it’s used. The most popular ways to use the oil are by applying it to the skin (topical application) or by inhaling it (aromatherapy).

Side effects from topical applications

Applying tea tree oil to the skin can cause irritation, particularly if it’s not diluted properly and is used in higher concentrations. Symptoms of skin irritation from tea tree oil can include:

Some people may develop an allergic reaction to tea tree oil. This is called allergic contact dermatitis and can cause a skin rash that may be red, swollen, and itchy. Use of older or improperly stored tea tree oil is often associated with these reactions, but fresh tea tree oil can cause this skin reaction, too.

A 2007 study found that abnormal breast growth coincided with tea tree and lavender oil use in a young boy who had been regularly using hair products containing both oils. The condition resolved after he stopped using the products.

Side effects from inhalation

Tea tree oil can also be used for aromatherapy. With this method, the oil is inhaled by using a diffuser, or through steam inhalation. Breathing in too much tea tree oil, or inhaling it for too long may lead to symptoms like:

Side effects from internal applications

Tea tree oil should never be used internally. It can be toxic and potentially fatal if you ingest it. If swallowed, symptoms may include:

Tea tree oil is toxic if swallowed. That’s why it should be kept in a safe place where children and pets can’t get to the oil and won’t be tempted to swallow it.

Side effects in children

Case reports of tea tree oil poisoning from 1994, 1995, and 2003 occurred in children who swallowed the oil. In these cases, the children recovered following emergency care at a hospital.

The symptoms of tea tree oil poisoning in children are similar to those in adults. They can include symptoms like:

  • feeling sleepy or drowsy
  • uncoordinated movement (ataxia)
  • confusion
  • unresponsiveness or loss of consciousness

Side effects in pets

Toxicity in pets has been reported not only when tea tree oil is ingested, but also when it’s applied topically.

One study reviewed incidents of exposure to 100 percent tea tree oil in cats and dogs over a 10-year period. Researchers found that in 89 percent of cases, tea tree oil was applied intentionally to the animals and not ingested accidentally.

The common symptoms of tea tree oil poisoning in dogs and cats can include:

  • increased drooling
  • extreme fatigue
  • muscle weakness
  • tremors
  • uncoordinated movement (ataxia)

Following essential oil safety guidelines may help reduce the risk of developing side effects. Some tips include:

  • Never consume or ingest tea tree oil.
  • Keep tea tree oil in a place that’s well out of reach of children and pets.
  • Never apply undiluted tea tree oil to your skin. According to the National Association for Holistic Aromatherapy (NAHA), essential oils that are used topically should be diluted in carrier oils, creams, or lotions, typically between a 1 and 5 percent dilution.
  • Dilute tea tree oil more if you have sensitive skin or are applying tea tree oil to a child’s skin. NAHA recommends a 0.5 to 2.5 percent dilution.
  • If you’re concerned about a potential skin reaction, test a little bit of diluted tea tree oil on your skin before using it on a larger area.
  • If you plan to use tea tree oil for aromatherapy, be sure the space you’re in is well ventilated. Avoid prolonged exposure to tea tree oil fumes.
  • Store tea tree oil in a dark bottle, as exposure to light can damage it.

Avoid using tea tree oil if you have eczema, as it could make your condition worse. Also, use caution with inhaling the oil if you have asthma, as it may worsen your symptoms.

Generally speaking, it’s a good rule of thumb to consult your doctor if you’re considering using tea tree oil but have questions or concerns. This is particularly true if you:

  • are pregnant
  • are breastfeeding
  • take prescription medications
  • have an underlying health condition

If you develop a skin irritation or allergic contact dermatitis after using tea tree oil, discontinue use. See your doctor if you have a skin reaction to tea tree oil that’s severe or affects a large area of your body.

Seek emergency care if you or someone else has swallowed tea tree oil or is experiencing signs of anaphylaxis in response to tea tree oil. Symptoms of anaphylaxis include:

  • wheezing or coughing
  • swelling of the throat or face
  • trouble breathing or swallowing
  • anxiety or confusion

Tea tree oil is an essential oil that can be used to help treat various conditions, including acne, athlete’s foot, and dandruff. It can also be found in some cosmetic and cleaning products.

There are several potential side effects of tea tree oil, including skin irritation and allergic contact dermatitis. Tea tree oil is toxic when ingested and should never be taken internally.

When using tea tree oil, be sure to follow essential oil safety guidelines. This includes diluting the oil properly before applying it to your skin, and not inhaling it for long periods of time. If you have health-related questions or concerns, consult your doctor before using tea tree oil.