Medicinally, the berries and the fragrant tops are employed. They contain "juniperin," sugar, resins, wax, fat, formic and acetic acids, and malates. The fresh tops have a balsamic odour, and a carminative, bitterish taste. The berries afford a yellow aromatic oil, which acts on the kidneys, and gives cordial warmth to the stomach. Forty berries should yield an ounce of the oil. Steeped in alcohol the berries make a capital ratafia; they are used in several confections, as well as for flavouring gin, being put into a spirit more common than the true geneva of Holland. The French obtain from these berries the Genièvre (Anglice "geneva"), from which we have taken our English word "gin." In France, Savoy, and Italy, the berries are largely collected, and are sometimes eaten as such, fifteen or twenty at a time, to stimulate the kidneys; or they are taken in powder for the same purpose. Being fragrant of smell, they have a warm, sweet, pungent flavour, which becomes bitter on further mastication.
Our British Pharmacopoeia orders a spirit of Juniper to be made for producing the like diuretic action in some forms of dropsy, so as to carry off the effused fluid by the kidneys. A teaspoonful of this spirit may be taken, well diluted with water, several times in the day. Of the essential oil the dose is from two to three drops on sugar, or with a tablespoonful of milk. These remedies are of service also in catarrh of the urinary passages; and if applied externally to painful local swellings, whether rheumatic, or neuralgic, the bruised berries afford prompt and lasting relief.
An infusion or decoction of the Juniper wood is sometimes given for the same affections, but less usefully, because the volatile oil becomes dissipated by the boiling heat. A "rob," or inspissated juice of the berries, is likewise often employed. Gerard said: "A decoction thereof is singular against an old cough." Gin is an ordinary malt spirit distilled a second time, with the addition of some Juniper berries. Formerly these berries were added to the malt in grinding, so that the spirit obtained therefrom was flavoured with the berries from the first, and surpassed all that could be made by any other method. At present gin is cheaply manufactured by leaving out the berries altogether, and giving the spirit a flavour by distilling it with a proportion of oil of turpentine, which resembles the Juniper berries in taste; and as this sophistication is less practised in Holland than elsewhere, it is best to order "Hollands," with water, as a drink for dropsical persons. By the use of Juniper berries Dr. Mayern cured some patients who were deplorably ill with epilepsy when all other remedies had failed. "Let the patient carry a bag of these berries about with him, and eat from ten to twenty every morning for a month or more, whilst fasting. Similarly for flatulent indigestion the berries may be most usefully given; on the first day, four berries; on the second, five; on the third, six; on the fourth, seven; and so on until twelve days, and fifteen berries are reached; after this the daily dose should be reduced by one berry until only five are taken in the day; which makes an admirable 'berry-cure.'" The berries are to be well masticated, and the husks may be afterwards either rejected or swallowed.
Juniper oil, used officinally, is distilled from the full-grown, unripe, green fruit. The Laplanders almost adore the tree, and they make a decoction of its ripe berries, when dried, to be drunk as tea, or coffee; whilst the Swedish peasantry prepare from the fresh berries a fermented beverage, which they drink cold, and an extract, which they eat with their bread for breakfast as we do butter.
Simon Pauli assures us these berries have performed wonders in curing the stone, he having personally treated cases thus, with incredible success. Schroder knew a nobleman of Germany, who freed himself from the intolerable symptoms of stone, by a constant use of these berries. Evelyn called them the "Forester's Panacea," "one of the most universal remedies in the world to our crazy Forester." Astrological botanists advise to pull the berries when the sun is in Virgo.
We read in an old tract (London, 1682) on The use of Juniper and Elder berries in our Publick Houses: "The simple decoction of these berries, sweetened with a little sugar candy, will afford liquors so pleasant to the eye, so grateful to the palate, and so beneficial to the body, that the wonder is they have not been courted and ushered into our Publick Houses, so great are the extraordinary beauty and vertues of these berries." "One ounce, well cleansed, bruised, and mashed, will be enough for almost a pint of water. When they are boiled together the vessel must be carefully stopt, and after the boiling is over one tablespoonful of sugar candy must be put in."
From rifts which occur spontaneously in the bark of the shrubs in warm countries issues a gum resembling frankincense. This gum, as Gerard teaches, "drieth ulcers which are hollow, and filleth them with flesh if they be cast thereon." "Being mixed with oil of roses, it healeth chaps of the hands and feet." Bergius said "the lignum (wood) of Juniper is diureticum, sudorificum, mundificans; the bacca (berry), diuretica, nutriens, diaphoretica." In Germany the berries are added to sauerkraut for flavouring it.
Virgil thought the odour exhaled by the Juniper tree noxious, and he speaks of the Juniperis gravis umbra:--
"Surgamus! solet esse gravis cantantibus umbra; Juniperis gravis umbra; nocent et frugibus umbrae." Eclog. X. v. 75.
But it is more scientific to suppose that the growth of Juniper trees should be encouraged near dwellings, because of the balsamic and antiseptic odours which they constantly exhale. The smoke of the leaves and wood was formerly believed to drive away "all infection and corruption of the aire which bringeth the plague, and such like contagious diseases."
Sprays of Juniper are frequently strewn over floors of apartments, so as to give out when trodden down, their agreeable odour which is supposed to promote sleep. Queen Elizabeth's bedchamber was sweetened with their fumes. In the French hospitals it is customary to burn Juniper berries with Rosemary for correcting vitiated air, and to prevent infection.
On the Continent the Juniper is regarded with much veneration, because it is thought to have saved the life of the Madonna, and of the infant Jesus, whom she hid under a Juniper bush when flying into Egypt from the assassins of Herod.
Virgil alludes to the Juniper as Cedar:--
"Disce et odoratam stabulis accendere cedrum." Georgic.
"But learn to burn within your sheltering rooms Sweet Juniper."
Its powerful odour is thought to defeat the keen scent of the hound; and a hunted hare when put to extremities will seek a safe retreat under cover of its branches. Elijah was sheltered from the persecutions of King Ahab by the Juniper tree; since which time it has been always regarded as an asylum, and a symbol of succour.
From the wood of the Juniperus oxycoedrus; an empyreumatic oil resembling liquid pitch, is obtained by dry distillation, this being named officinally, Huile de cade, or Oleum cadinum, otherwise "Juniper tar." It is found to be most useful as an external stimulant for curing psoriasis and chronic eczema of the skin. A recognised ointment is made with this and yellow wax, Unguentum olei cadini.
In Italy stables are popularly thought to be protected by a sprig of Juniper from demons and thunderbolts, just as we suppose the magic horseshoe to be protective to our houses and offices.
Source: Herbal Simples Approved for Modern Uses of Cure, William Thomas Fernie