Dilution: Use “drop-by drop dilution” by first mixing 1 drop of eucalyptus into 1ml base oil, and then increasing the dilution multiplier. Vitamin E in sweet almond oil can enhance antioxidant effects. The instructor of the Aromatherapy Course in Australia will instruct students on how to use “gradient diluting” to make sure that the eucalyptus is evenly distributed in the base oil. This helps to prevent excessive local concentration.

Local test: The “sandwich method” is recommended. Apply the diluent to the back of the ear, and then cover it with a breathable bandage. If itching or erythema occurs within 24 hours of application, the area should be cleaned with vegetable oil. Dermatologists advise that people who have a good tolerance for eucalyptus oils should test them locally before using a new brand or batch.

Frequency of use: For acne care, it is recommended to use “pulse use”, that is, use it for 3 consecutive days and stop using it for 2 days to avoid reduced skin tolerance. In Singapore’s skin clinics, doctors will develop personalized eucalyptus oil usage plans based on the severity of the patient’s acne to achieve the best treatment effect.​

Combination enhancement: When combined with 2% salicylic acid, it can enhance the acne-removing effect; adding 0.5% sodium hyaluronate can relieve the dry skin that may be caused by eucalyptus oil. In a Japanese skincare laboratory, researchers combined eucalyptus oil with ceramide to develop a repair product for sensitive skin, which not only exerts the antibacterial effect of eucalyptus oil, but also repairs the skin barrier.