Botanical name: 

The leaves of Eucalyptus Globulus, Labillardiere. Collected from the older parts of the tree. (Nat. Ord. Myrtaceae.) A native tree of Australia; cultivated elsewhere.
Common Name: Blue Gum Leaves.

Principal Constituents.—A volatile oil (Oleum Eucalypti) composed largely of eucalyptol (cineol) (C10H18O), and a resin.
Preparations.—1. Oleum Eucalypti, Oil of Eucalyptus (contains a large proportion, not less than 70 per cent, of eucalyptol). it is colorless or pale yellow, aromatic and pungent, and has a spicy, cooling taste. Dose, 1 to 10 drops.
2. Eucalyptol, a neutral body derived from the oil. It is a colorless, spicy, aromatic fluid, with a cooling taste. Dose, 1 to 10 drops.
3. Specific Medicine Eucalyptus. Dose, 5 to 30 drops.

Specific Indications.—Cold extremities and cold perspiration; perspiration during chill; sense of coldness and weight in the intestines; chronic mucous or muco-purulent discharges; pus in the urine; pasty, bad-smelling tongue; fetid excretions; fetid sore throat; fetid catarrhal states of the broncho-pulmonary tract; chronic ague with exhaustive discharges.

Action.—Eucalyptus, and its oil and derivative, are gentle stimulants when given in small doses. Large doses are irritant and may cause gastrointestinal inflammation and renal congestion. Muscular prostration occurs from overdoses. Blood pressure is lowered by full doses. All the secretions are stimulated when these agents are given in medicinal amounts. All preparations of Eucalyptus are considered antiperiodic and the planting of groves and trees in miasmatic swamps and low grounds is thought to render the air free from malarial miasm. The probabilities are that the enormous quantities of water absorbed by these trees does good by drying the swamps and thus making them poor breeding places for malaria-bearing insects. It is said that a part of the deadly Roman Campagna has been rendered habitable by the introduction of Eucalyptus groves.

Therapy.—External. Eucalyptus preparations are antiseptic and disinfectant. They may be sprinkled or sprayed upon offensive material and used to disinfect and deodorize the sick room. They also may form an ingredient of antiseptic poultices and ointments. Dropped upon hot water, or used in suitable oil dilution in sprays, they are useful as throat and pulmonary antiseptics and stimulants. Eucalyptol is especially much employed in subacute inflammations and chronic diseases of the broncho-pulmonic tract, with fetor, relaxation and abundant secretions. Used upon cancerous surfaces they mask the fetid odor and give some relief from pain. The following is an ideal vaginal wash for offensive leucorrhea: ℞. Sea Salt, 1 ℔.; Fluidextract of Eucalyptus or Specific Medicine Eucalyptus, ½ fluidounce. Mix in a glass or tin container. Sig.: One tablespoonful to 1 pint of hot water, and inject with a glass syringe. All preparations of eucalyptus may be used from full strength to any desired dilution upon old ulcers, wounds, gonorrhoeal discharges, ozoena, septicemia, and gangrene; all with free but fetid discharges. Inhalations of them are especially useful in pulmonary gangrene.

Internal. Eucalyptus is a fine stimulating expectorant for broncho-pulmonary catarrhal disorders, when no very active inflammation is present. It restrains discharges, facilitates expectoration, and deodorizes and antisepticizes the sputum. Chronic bronchitis, bronchorrhea, and the debility, with difficult expectoration, lingering in the wake of bronchopneumonia and lobar pneumonia are conditions in which it is of very great value.

Agents of this type, which may be compared to the turpentines, and which influence the respiratory membranes, usually are valuable for similar uses in the urino-genital tract. Thus we find eucalyptus an alterative and antipyic in pyelitis and in catarrhal and purulent cystitis, particularly in the aged. Being eliminated by all the mucous surfaces, it exerts its antiseptic influence upon them in all parts of the body. While the oil and eucalyptol are popular with many, we prefer the specific medicine or the fluidextract for most purposes.

Eucalyptus is a stimulating antiseptic for the angina of scarlatina, for which by some it is administered internally. This should be done with great care, however, for the drug is liable to produce congestion of the kidneys, one of the dreaded complications which is easily provoked in the acute exanthemata. If acute desquamative nephritis is present it should not be employed; in the advanced stage of chronic nephritis with very marked fetor in the urine, and scanty secretion of urine, very small doses of eucalyptus may be cautiously tried. Eucalyptus and its preparations are distinctly contraindicated when acute inflammation of any part exists.

The antimalarial properties of eucalyptus are taken advantage of in cases of malarial infection that do not respond to quinine or in which the quinine has an otherwise undesired effect. The more chronic the cases—without distinct cycles—the better the drug seems to act. It is also naturally used for many of the complications or results of chronic malarial cachexia, as periodic headache and neuralgia. It is only in occasional cases of malarial fever that it does a great deal of good, especially acting best if there are exhaustive discharges, but it is never without some beneficial power. It is not to be compared to cinchona medication in the ordinary run of malarial fevers. Used according to indications as given above, eucalyptus is a very satisfactory and pleasant medicine. It is best given in syrup or glycerin.

The Eclectic Materia Medica, Pharmacology and Therapeutics, 1922, was written by Harvey Wickes Felter, M.D.