These are medicines calculated to produce an increased secretion from the mucous membrane of the nostrils. As all of them are apt to cause sneezing, they are also called sternutatories. No medicines are taken internally with this special view. All are applied directly to the interior of the nostrils themselves. So far as the increased secretion is concerned, they operate by directly stimulating the secreting tissue. Sneezing is produced through an impression transmitted to the nervous centres in the encephalon, which then call into action, and combine to one purpose, the various muscles of the chest, neck, and face, concerned in the act. At the same time that the impression is thus made on the nervous centres, which leads to the act of sneezing, a sensation is produced, of greater or less strength, which sometimes serves important therapeutic purposes.

The agencies through which errhines operate beneficially in disease, are 1. a simple stimulant or excitant impression on the Schneiderian membrane; 2. an increased secretion by which they deplete from the vessels; 3. a revulsive influence on neighbouring parts; and 4. the various influences of the sensation excited, and acts produced, through the nervous centres.

1. By their stimulation of the membrane, they sometimes prove useful in defective secretion of the nasal mucus, or unhealthy dryness of the membrane, in chronic inflammation of the same, and in paralysis of the sense of smell, and of the soft palate.

2. By depletion, they tend to relieve inflammatory conditions of the neighbouring parts, as of the antra, the frontal sinuses, the Eustachian tube, the ears, eyes, face, and scalp.

3. Their revulsive influence is useful in the same inflammatory affections, and also in neuralgia of different parts of the face and scalp. Obstinate chronic ophthalmia, excessive sensibility of the retina, amaurosis, rheumatic conditions of the eye, frontal and facial neuralgia, earache, chronic otitis and deafness, obstinate headaches, and even chronic inflammation of the brain or its meninges, are complaints which offer indications for the use of these medicines.

4. in reference to their excitant impression on the cerebral centres, they are used to obviate faintness or syncope, to restore suspended respiration, to compose irregularities of respiration of a purely nervous character, to produce a shock which may rouse from insensibility or coma, when not dependent on active congestion or compression of the brain. Prof. Laycock, of Edinburgh, has found great advantage from them in suspending and moderating epileptic paroxysms. (Med. Times and Gaz., May, 1865, p. 463.) By the sneezing they excite, they aid in expelling foreign bodies and accumulated mucus from the nasal and respiratory passages, rouse sensibility by their action on the brain, and produce a shock on the system, which may aid in the supersession of paroxysmal affections, or in breaking up commencing attacks of disease. But care must be taken not to employ this measure in cases with active congestion of the brain, or a tendency towards it.

It must be borne in mind, in the use of errhines, that some of them, as tobacco and turpeth mineral, may possibly be absorbed from the mucous membrane, and that they are liable also to be swallowed to a greater or less extent.

Like most other medicines, they suffer a diminution of power by long continued use.

There are no particular limits to the frequency of their exhibition; the physician being influenced upon this point by various considerations connected with the activity of the medicine, and the particular indication to be fulfilled.

Most substances, whether acrid or not, will act as errhines when snuffed up the nostrils, in the state of powder, if not impalpable; the mucous membranes of these cavities having been made exquisitely sensitive, in order to guard the lungs against the intrusion of noxious agents. Powdered gum or sugar will often produce this effect; and I have known water, a little too hot or a little too cold, to act in a similar manner. But, generally speaking, it is only medicines capable of impressing the nostrils dynamically, that are used for the purpose.

1. Aromatic Powders. Various aromatic herbs, in the form of powder, have been long used as errhines; the choice being directed to them probably by their agreeable odour. Rosemary, sage, the mints, lavender, common sweet marjoram, thyme, or horehound may be used, when only a mild impression is desired.

2. Tobacco may be considered as next in the ascending order of efficiency. This is so well known as an errhine, in the different forms of snuff, that it requires no comment here. it is one of the substances to which the nostrils soonest become accustomed; so that to maintain a given impression, for a considerable time, it is necessary to increase the quantity very greatly. in the use of it, the physician should bear in mind its effects on the stomach and nervous system generally, both of which may be produced by this mode of exhibition; and should also, before prescribing it, give some weight to the consideration, that he may be laying the basis of a habit, which is certainly not very cleanly, to say the least of it, and may be injurious to the health. The effect of snuff in impairing the voice, when much and long used, is notorious; and I have no doubt that its excessive use has the same injurious effects upon the digestive organs, and the nervous system, as smoking and chewing, though probably not in an equal degree.

3. Asarabacca (Asarum Europaeum) is a small, herbaceous, perennial, European plant, all parts of which possess acrid properties. Both the leaves and root are used. The leaves have long footstalks, are kidney-shaped, somewhat hairy on the surface, nearly inodorous, and of a bitter, nauseous, and acrid taste. The roots are about as thick as a quill, quadrangular, knotted, contorted, of a grayish colour, a somewhat pungent odour, and an acrid taste. Taken internally, asarabacca operates as an emetic, and, before the discovery of ipecacuanha, was considerably used as such; but at present it is employed almost exclusively as an errhine. Snuffed up the nostrils in the state of powder, it excites sneezing, and causes an increased flow of mucus, which is sometimes attended with blood, and is said occasionally to continue for several days. The leaves are milder than the root, and may be used in the quantity of three or four grains. Of the powdered root, only one or two grains should be used. They may be employed every night.

4. White Hellebore (Veratrum Album, U. S.), which is the root of Veratrum album, has been already sufficiently described (II. 161). The powdered root, when introduced into the nostrils, causes severe and painful irritation, with violent sneezing, and copious discharge of mucus. it is the most powerful of the errhines yet mentioned, and is not without danger, even in this mode of exhibition, if used in excess. Three grains of an extract prepared from it, introduced into the nostrils of a cat, caused death in less than twenty-four hours. it has been employed as an errhine more especially in cases of amaurosis. - Before exhibition, it should always be diluted with some mild substance, as powdered gum arabic or powdered liquorice root, of which five parts may be employed to one of the medicine.

5. Euphorbium is a concrete resinous exudation of one or more species of Euphorbia, growing in the North of Africa. it appears to exude around the thorns or prickles of the plant, where it hardens. it is in the form of irregular or roundish tears, usually about the size of a small pea, somewhat friable, with one or two holes produced by the prickles, of a yellowish or slightly reddish colour, nearly inodorous, and of a taste which, though agreeable at first, becomes at length excessively acrid and burning. They are more or less intermingled with dust, produced by their attrition, which excites violent sneezing when drawn into the nostrils. Euphorbium is a severe local irritant, producing inflammation and vesication of the skin where applied, and internally operating as a violent emeto-cathartic. It is supposed also by some to have narcotic powers. It is occasionally used as a rubefacient or vesicatory application, especially in veterinary practice; but it is retained among the officinal medicines chiefly, I presume, as an errhine; though, even in this capacity, it is not much employed. It has been used mainly in amaurosis and deafness. It should never be applied undiluted, but always mixed with six or eight times its weight of some inert powder, as powdered gum arabic or liquorice root, starch, or flour. Not more than one or two grains should be employed at once.

6. Turpeth Mineral (Hydrargyri Sulphas Flava, U.S.) has been already described (ii. 483). We have here to consider it simply as an errhine. In this capacity, it is one of the best of the class. Less powerfully irritant than the last two mentioned, it is more efficient than the others, and may be employed whenever a decided impression is required. It has been used chiefly in chronic ophthalmia, and cephalic affections; and, as the complaints in which it is most useful are of an inflammatory character, it is not improbable that, in its curative influence, its errhine properties are a good deal aided by its alterative action as a mercurial. It sometimes salivates when applied to the nostrils. One grain may be employed at once as an errhine, diluted with four or five parts of flour or starch.