The common side-effects of using tea tree oil include diarrhea, inflammation of the mouth, muscle tremors, fatigue, bad breath, ear damage, drowsiness and nausea, according to Mayo Clinic. It can also cause swelling, skin dryness, burning, itching and redness, as WebMD indicates.
Tea tree oil is typically applied to the skin for treating acne, fungal nail infections, athletes foot, ringworm, lice and scabies. It also acts as an antiseptic, and it can be used to treat burns, boils, herpes labialis, sore throat, ear infections, stings and insect bites, and infections of the nose and mouth. It is also useful in the treatment of pulmonary inflammation, bronchial congestion and coughing, notes WebMD.
Tea tree oil is very effective if used wisely and in recommended dosages. The dose for acne is a daily application of a 5 percent gel to the affected areas. For nail fungus, patients should apply a 100 percent solution of tea tree oil twice daily for six months. The dose for athlete's foot treatment is a 25 percent or 50 percent solution, which has to be applied twice a day for one month, according to MedicineNet.
It is not advisable to take tea tree oil by mouth, especially for individuals sensitive to this product or who experience allergic reactions. It should never be used by boys before puberty or applied in the middle ear because it can cause reversible gynecomastia and ear toxicity, respectively, reports Mayo Clinic.