Health Benefits of
Scientifically known as Eucalyptus citriodora, eucalyptus contains volatile oils with medicinal properties. Eucalyptus is one of the most cultivated plants globally. The largest eucalyptus producers include China, India, Portugal, Chile, and South Africa. Eucalyptus pulp is obtained and commercialized for different uses.  The following sections discuss the health benefits of eucalyptus.
Eucalyptus for Headache
Eucalyptus oil in conjunction with peppermint oil and ethanol is beneficial for treating tension-type headaches. Eucalyptus oil massage on the temple and forehead relaxes temporal muscles and improves the mood status of an individual. This also decreases sensitivity to pain elicited due to muscle ischemia. 
Eucalyptus for Allergic Reactions
Eucalyptus modulates allergic reactions and related conditions such as allergic dermatitis by inhibiting IgE and degranulation of mast cells. Eucalyptus reduces the thickening of the stratum corneum and suppresses leukocytic infiltration of the dermis. Eucalyptus also alleviates swelling of the dermis. 1,8-cineole present in eucalyptus oil is responsible for the above-mentioned anti-allergic effects. 1,8-cineole reduces mast cell degranulation by inhibiting the release of histamine, IL-4, and IL-13. 
Eucalyptus Strengthens Skin Barrier
Eucalyptus induces the synthesis of ceramides, sphingomyelin, and glucosylceramide in the skin. This restores the concentration of these compounds in the skin, thus, improving the water-holding capacity of the stratum corneum. Increased levels of ceramide in keratinocytes also improve the barrier function of the stratum corneum. This will prevent the skin from losing excessive water and remaining soft and smooth. Moreover, an intact stratum corneum barrier prevents pathogens from invading the deeper layers of skin, hence, reducing the risk of skin infections. Macrocarpal A present in eucalyptus extract increases the activity of enzymes responsible for ceramide production. 
Photoprotective Effects of Eucalyptus
Ultraviolet radiation of the sun induces skin damage both directly and indirectly via the production of reactive oxygen species and free radicals. Eucalyptus inhibits the transcription factor responsible for the production of matrix metalloproteinases (MMP), enzymes that catalyze the degradation of collagen. Eucalyptus also upregulates the genetic expression of elastin, collagen, and TGF-beta. 
Antibacterial Activity of Eucalyptus
Eucalyptus impairs the membrane integrity of bacteria and promotes the leakage of bacterial cytoplasmic constituents that leads to the death of bacteria.