This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol1", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
In great excess, camphor sometimes occasions nausea and vomiting, by which it is discharged, and ill effects averted. If not speedily thrown off from the stomach, it gives rise to anxiety, vertigo, disordered or obtunded hearing and vision, delirium, insensibility, muscular twitchings, couvulsions, and deep stupor. Along with these symptoms there are usually diminution in the frequency and force of the pulse, paleness of the face, and coolness of the skin, which is sometimes bathed in cold sweat. The symptoms come on usually in less than half an hour, increase gradually in intensity, and in the course of an hour or two end in unconsciousness. If the poison is evacuated, they will go off quickly; otherwise, they may continue several hours, and gradually decline, the patient returning to consciousness, but with some confusion of mind and feebleness of memory remaining for a longer or shorter time Except in the case of an infant, of about eighteen months, who died from the effects of the poison, after taking about ten grains, no instance of fatal result is on record; but in many instances the symptoms have been very alarming, and quite sufficient to suggest caution in the use of large doses. It is a singular fact that, in some of these cases of poisoning, there have been at first evidences of high circulatory excitement, with flushed face, and other symptoms of determination of blood to the head, followed by a state of depression; while in other cases the depressed condition has first occurred, and the symptoms of excitement, amounting even to fever, have followed. It has been attempted to explain the latter by the reaction following depression; but we do not see the same phenomena succeeding the prostrating influence of real direct sedatives, such as conium, chloroform, digitalis, hydrocyanic acid, etc. It is more probable that they were the result of the direct action of the poison on the brain; and the different states of excitement and prostration were probably merely the results of different degrees of excitant or irritant influence on the cerebral centres, in one instance being only sufficient to stimulate them to excessive action, in the other overwhelming them with an active congestion, and thus preventing their due influence on the functions over which they preside, whether of the heart, lungs, or special senses. The occurrence of febrile symptoms, and obvious cerebral excitement, after the depressing effects have been for some time experienced, may be owing to a subsidence of the active congestion of the cerebral centres to a point, at which their operations are unembarrassed, and at which, consequently, they are enabled to extend the direct effects of their irritation throughout the system. If any physician will ask himself the question, whether he would venture to give camphor, in large doses, in acute inflammation or active congestion of the brain, he will at least determine what is his own real belief of its action. If he agree with the author in thinking that it could do only injury under such circumstances, he will be disposed to rank camphor, as is here done, among the cerebral stimulants. Until he is prepared to administer it as an effectual remedy in such cases, he cannot be thoroughly convinced of its direct sedative properties.
The quantity in which camphor is capable of producing poisonous effects varies exceedingly, according to individual peculiarity, or to circumstances not well understood. Thus, while Mr. Alexander, of Edinburgh, suffered the most threatening symptoms, including convulsions and stupor, from forty grains, and even twenty grains have produced alarming effects, more than two drachms have been taken without serious consequences. The ten grains which proved fatal in the child of eighteen months, are probably equivalent to eight or ten times as much given to an adult.
The main remedy in poisoning from camphor is to evacuate the stomach. The after treatment depends altogether on the symptoms presented; but, in general, little else is required.