The oil obtained from the liver of Gadus morrhua, and other species of codfish. An exceedingly complex substance, containing glycerin, acetic acid, and several fatty acids, iodine, chlorine, and traces of bromine, phosphorus, and phosphoric acid, and various other constituents. There are three varieties: the pale yellow, light brown, and dark. The pale oil is the purest, being prepared by forcing steam at high pressure through the livers, and is less nauseous than the dark oil. This is the official variety.
Cod-liver oil is an alterative to the general nutrition in various diseased conditions, and is more truly a food than a medicine, as it supplies the need of the tissues for fat. Fat produces force, and is utilized by every part of the body in quantities directly proportioned to the activity of the different tissues. The nervous system needs the largest amount; the muscular, the next largest. Having been elaborated by the liver of the fish, cod-liver oil is more easily digested than other fats.
The smell of cod-liver oil is unpleasant and sometimes causes nausea. This may be avoided by taking some peppermint into the mouth just before taking the oil, and by avoiding bringing it into direct line with the nose. All patients do not know how to take oil; by tossing it into the mouth and not allowing the lips to touch it, it is less disagreeable.
It is best to mix no other medicines with cod-liver oil, except hypophosphites. If other medicines come at the same time they should be given separately. It may be given in any of the ways in which castor oil is given; it is almost always well taken if floated in a little brandy or wine, or lemon juice. These precautions about giving it do not necessarily apply to the various emulsions of oil, which are usually not at all hard to take. The proper time to administer cod-liver oil is when digestion is at its height.
In overdoses, or when first taken, it may disorder the stomach, or cause temporary relaxation of the bowels. It sometimes causes an eczema.
Emulsions of cod-liver oil spoil in a short time, and patients should not be encouraged to buy the ready-made preparations in the shops.
In giving cod-liver oil the faeces must be watched, to see if any is carried away undigested.
When cod-liver oil cannot be taken by mouth it may be administered by inunction, a few drams of the oil being rubbed into the skin of the chest or abdomen at night before retiring. When used in this way it is especially valuable for children with malnutrition.
Average dose, ʒ iiss.-10 mils, from three quarters of an hour to an hour after meals,