Eucalyptus oil comes from the leaves of a tree native to Australia. People inhale it, often via steam or a diffuser, to ease a stuffy nose. When diluted and rubbed on the skin, it can soothe minor muscle aches.
Some people take dried leaf extracts internally, but this can cause stomach upset or toxicity. Never swallow the essential oil.
Eucalyptus essential oil is toxic if swallowed, especially for children. Keep it away from infants and young children. Always dilute it with a carrier oil before putting it on skin to avoid irritation. Talk to a doctor before using it if you have asthma, liver problems, or are pregnant or breastfeeding.