Eucalyptus oil is the generic name for distilled oil from the leaf of Eucalyptus. Eucalyptus oils in the trade are categorized into three broad types according to their composition and main end-use: medicinal, perfumery and industrial. The dried leaves and oil are used to make medicine. Though eucalyptus is used medicinally for many purposes, there isn't enough scientific evidence so far to rate it as effective for any of them. Eucalyptus leaf is used for infections, fever, upset stomach, and to help loosen coughs. The leaf is also used for treating respiratory tract infections, whooping cough, asthma, pulmonary tuberculosis, osteoarthritis, joint pain (rheumatism), acne, wounds, poorly healing ulcers, burns, bacterial dysentery, ringworms, liver and gallbladder problems, loss of appetite, and cancer.
Eucalyptus oil should not be taken by mouth or applied to the skin full-strength. It must be diluted for safety. Diluted eucalyptus oil is applied directly to the skin for pain and swelling of respiratory tract mucous membranes, joint pain, genital herpes, and nasal stuffiness. It is also used as an insect repellent. In dentistry, eucalyptus oil is included in products used as sealers and solvents for root canal fillings.

Benefits
1. Inhaled eucalyptus oil vapor is a decongestant and treatment for bronchitis.
2. Diluted form of eucalyptus oil is taken orally for pain and inflammation of respiratory tract mucous membranes, coughs, asthma, bronchitis, sinus pain and inflammation, and respiratory infections.
3. Eucalyptus oil is also used as a fragrance component to impart a fresh and clean aroma in soaps, detergents, lotions and perfumes. It is known for its pungent, intoxicating scent.
4. Eucalyptus oil is used in flavouring. its used as a flavouring at low levels (0.002%) in various products, including baked goods, confectionery, meat products and beverages
5. Eucalyptus oil is also used in personal hygiene products for antimicrobial properties in dental care[12] and soaps. It can also be applied to wounds to prevent infection.
6.  Eucalyptus oil is used as an insect repellent and biopesticide.
7. Eucalyptamint "produced significant physiologic responses that may be beneficial for pain relief and/or useful to athletes as a passive form of warm-up.
8. This oil exhibits antibacterial activity against cariogenic (tooth decay-causing) and periodontopathic bacteria.
9. Eucalyptus oil extract is said to implement the innate cell-mediated immune response.
10. It is commonly mixed with other oils to make it more easily absorbed by your skin.
11. Eucalyptus oil may help soothe your mucous membranes (such as for allergies and asthma), by adding a drop of the oil on an organic cotton ball and sniff it several times a day. Also recommend adding a few drops to water or a nebulizer as steam therapy, or you can use a few drops in your bath water.