External

Oil of turpentine has, to a marked degree, the action of other volatile oils. Thus applied to the skin, especially if rubbed in, it causes the vessels to dilate, there is a sense of warmth, the part becomes red, and subsequently common sensation is blunted. The oil is therefore rubefacient, irritant, and counter-irritant. If enough is applied, it is a vesicant.

Like the other volatile oils it is antiseptic and disinfectant. It is absorbed by the unbroken skin.

Internal

Alimentary canal. - Oil of turpentine has the same stimulant effect when locally applied to the mouth and pharynx as it has on the skin, and in the stomach it powerfully dilates the vessels, increases peristalsis and the gastric secretion, and reflexly stimulates the heart, but on account of its nauseous taste it is not used for these properties, which it has in common with other volatile oils. Its effects on the intestine are the same as those on the stomach, the most marked being its energetic stimulation of the muscular coat, hence it is a strong carminative, expelling gas from the bowels. If a large amount is given, the excitation of the muscular coat leads to purging, the motions often containing much blood, haemorrhage resulting from the great vascular dilatation. Oil of turpentine is anthelmintic, killing the tapeworm when administered in doses of 1/2 to 4 fl. dr. 2. to 15. c.c.; but this treatment may cause severe symptoms. When given as an enema it kills the threadworm.

Circulation. - Oil of turpentine is readily absorbed. We do not know in what form it circulates. Statements concerning its action on the heart and vessels are very discordant, probably because different experimenters have used different varieties of oil of turpentine; but most specimens appear first to stimulate the heart, in some degree at least, directly, for oil of turpentine locally applied will excite the excised heart, increasing the force and frequency of the cardiac beat. It contracts the vessels, and therefore it is a haemostatic. The blood-pressure rises. After a large dose of any variety this stimulation is followed by depression, the heart beats feebly, the vessels dilate, and the blood-pressure falls.

Respiration. - When inhaled, oil of turpentine acts on the bronchial mucous membrane as it does on the skin, irritating it, dilating the vessels, increasing and disinfecting the secretion, stimulating the muscles of the bronchi, and reflexly exciting cough. If given internally, since some of it is excreted by the bronchial mucous membrane, similar effects are produced. At the same time the activity of the respiratory movements is in-creased, so that the drug is a powerful expectorant.

Nervous system. - Oil of turpentine in large doses is a severe depressant to the nervous system, producing languor, dulness, sleepiness, and unsteady gait. Toxic doses cause coma and paralyze the sensory nerves; consequently reflex action is abolished.

Kidneys. - It acts more powerfully on these than almost any other volatile oil. Even moderate doses may lead to pain in the loins, scanty, high-colored urine, albuminuria, and haematuria. The urinary passages are also irritated; consequently, owing to muscular spasm, there is difficulty in passing water, micturition is painful, and a sensation of heat in the perinaeum is present (these symptoms constitute strangury). If a large dose has been given, the urine may be completely suppressed. Turpentine causes the urine to smell of violets.

Skin. - Oil of turpentine is excreted by the skin, and may cause an erythematous rash.

Some is probably excreted by the milk, bile and intestinal mucous membrane.

It is said to be a mild antipyretic. Old oil of turpentine containing oxygen (see p. 239) is an antidote to phosphorus, and it is stated that that and the French oil are preferable, but this is doubtful.