As Grieve stresses: 'Great care must be exercised though, as some people are particularly sensitive to the plant and many severe cases of poisoning have resulted from its use, especially if taken internally.'

Grieve's classic 'A Modern Herbal': 'In countries where Arnica is indigenous, it has long been a popular remedy. In the North American colonies the flowers are used in preference to the rhizome. They have a discutient property. The tincture is used for external application to sprains, bruises, and wounds, and as a paint for chilblains when the skin is unbroken. Repeated applications may produce severe inflammation.'

'It is seldom used internally, because of its irritant effect on the stomach. Its action is stimulant and diuretic, and it is chiefly used in low fevers and paralytie affections.'

'Arnica flowers are sometimes adulterated with other composite flowers, especially Calendula officinalis, Inula brittanica, Kragapogon pratensis, and Scorzonera humilis.'

'A homoeopathic tincture, X6, has been used successfully in the treatment of epilepsy; also for seasickness, 3 X before sailing, and every hour on board till comfortable.'

'For tender feet a foot-bath of hot water containing 1/2 oz. of the tineture has brought great relief. Applied to the scalp it will make the hair grow.'

'Great care must be exercised though, as some people are particularly sensitive to the plant and many severe cases of poisoning have resulted from its use, especially if taken internally.'

King's 1898 Dispensatory: 'Locally arnica is irritant, the preparations of the flowers being most powerful. Strong preparations should not be applied full strength, for in some instances of tender skin, or in accidents occurring after its use, an erysipelatous inflammation has followed. Even when used as a local dressing for wounds dangerous inflammation, with vesication, has occurred.'

'Externally arnica is used in the form of an infusion, a fomentation, or diluted tincture of the flowers, both to prevent and discuss local inflammations, to remove ecchymosis, and as a dressing for cuts, lacerations, contusions, etc. For this purpose the infusion is attended with the least danger.'

'The late Prof. J. M. Maisch prepared a fluid extract of arnica, which has been found very useful as an application for the bites of mosquitoes and other insects, thus: Exhaust powdered arnica flowers, 1 pound, with diluted alcohol; filter; evaporate to the consistence of an extract, and redissolve this in 2 pints of ordinary alcohol. By adding 4 ounces of this fluid extract to 1 pint of glycerin, placing the mixture on a water-bath, so as to expel the alcohol, an elegant glycerole of arnica may be made; it may be made stronger if desired. This may be used in all cases where the local action of arnica is desired.'

American Materia Medica, 1919 (Ellingwood): 'The agent is specific to bruised, sore, lacerated, contused, muscular structure. It may be applied diluted externally and should be used internally for the same purpose.'

'These symptoms may be present from disease, deep muscular soreness—tenderness on pressure in deep muscular structures. In advanced disease, where these symptoms are present with marked general enfeeblement, impairment of innervation, with weak circulation, with a tendency towards permanent prostration, the remedy is specifically indicated.'

'When there is muscular pain and soreness, which is increased by muscular movement, or soreness in the back, as if from strain, the remedy is useful.'

'Where there is inflammation of any organ, with general diffused muscular soreness, the agent in small doses is indicated. Where there is inflammation of any organ from traumatic causes—severe injury to the parts, this remedy must be given.'

'In the muscular soreness, pain, and general physical discomfort that follows confinement, especially after difficult labor, this agent used both externally and internally will produce immediate benefits. Internally from fifteen to thirty drops in four ounces of water, a teaspoonful every hour will quickly relieve the muscular soreness or extreme lameness from the severe protracted muscular strain. Externally one part to five of warm water may be applied on compresses over the lame parts, and as soon as soreness of the breasts occur it may be applied over the breasts for a time.'

'Therapy: In small doses, arnica causes increased perspiration, increased secretion of urine, and an accelerated pulse. Its tonic influence upon the nervous system, and directly upon the heart and circulatory organs, make it a useful remedy indeed. In adynamic fevers, we have so few remedies possessing sedative properties, which do not depress, that each should be studied in this line, and arnica is especially available. It must be given in small doses frequently repeated, in the line of its indications. The indications for bryonia, rhus tox, or belladonna, or perhaps cactus, may be present at the same time.'

'Arnica is selected for internal use when there has been a severe injury, with fever, or in surgical fever, where there has been shock and general prostration. In all cases after severe cutting operations, where there has been destruction of muscular tissue, soreness follows and pain, which is ameliorated to an excellent advantage by the internal use of small doses of arnica.'

'In low fevers, where the nervous system is greatly at fault, it not only controls the temperature, but increases the nerve-power, overcoming depression and debility, especially in severe, protracted fevers where the exhaustion results from loss of nerve force and where there is marked depression; if there be excessive night sweat, colloquative diarrhea, incontinence of urine or feces, feeble respiratory power where difficulty of breathing keeps the patient awake. It may be given in conjunction with other specifically indicated remedies to excellent advantage, where there is low muttering delirium, where the tongue is dry and where the mouth and throat seem to be clogged with foul, stringy mucus.'

'When there are typhoid conditions present, with inflammation of the respiratory organs, the influence of this agent is much like phosphorous, stimulating the respiration and encouraging the oxygen carrying power of the blood. Many of the milder forms of acute, or chronic paralysis, are benefited by this remedy.'

'It is useful in those forms where mania or delirium tremens are present.'

'In any case where it is indicated externally, it may be given internally at the same time. Its influence is greatly enhanced.'

'Soreness in the small of the back, lame back, general weakness of the muscles of the back, with soreness prevailing, sickening backache in the region of the kidneys, are all benefited by arnica. It not only relieves the soreness and the bruised conditions, when given internally, but quickly overcomes the ecchymosis.'

'As an external application, to cuts, bruises, lacerations, and sores, arnica has long been a popular domestic remedy. It is used in full strength, but the best results are not so attained. It is more serviceable when diluted with from one to six parts of warm water. It is a stimulant to the skin, promoting absorption of nutritive material. It undoubtedly assists in carrying off the broken down tissue, which results from the traumatism, and promotes rapid repair. I have observed its influence to be greatly facilitated by combining it with a nutritional substance. In cases where the muscles beneath the skin were severely lacerated, torn and bruised, I have applied one part of arnica with five parts of warm fresh sweet milk, keeping the application warm, covered with a protective dressing, and renewed every two or three hours. It is incredible how rapidly the restoration will take place under these circumstances.'

'In debilitated conditions, where there are old sores of long standing or cold abscesses, this agent may be applied in conjunction with bovinine and will accomplish excellent results.'

'It is desirable that the agent should be studied more thoroughly, in the line of its internal use, in surgical fevers with shock, and in conjunction with external applications after general bruising and laceration, and in extreme cases of adynamia.'