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Besides the local irritation of the stomach, the most frequent undesirable effects are those upon the skin and mucous membranes.

1. Skin

The skin lesion usually shows as irregularly scattered pimples, the chief sites of which are the face, shoulders, neck, and back. It has been thought that the skin affection was due to elimination of the drug by the sebaceous glands, and its decomposition by the fatty acids of the sebaceous secretion. But many investigators have failed to find either free iodine or iodide in the sebaceous secretion, and the dermatopathologists agree that the changes begin in the papillary layer and not in the glands (Stelwagon).

Other skin lesions than acne may make their appearance, as urticaria or a vesicular or bullous or hemorrhagic-bullous or purpuric eruption, or disseminated, bright or dusky red, and painful nodules. A few cases of carbuncle formation with serious destruction of the subdermal tissues are reported, even resulting in death. The serious eruptions usually occur in patients with much lowered vitality, and especially in those with chronic nephritis.

2. Mucous Membranes

The mucous membranes chiefly irritated are the conjunctivae and those of nose, throat, bronchi, and stomach. A not unusual effect is that of a severe cold in the head, with watery, injected eyes, headache, and general malaise; there may be, in addition, nausea, salivation, and tender teeth and gums. The patients think they have influenza. A number of cases of edema of the glottis have been reported, also purpuric eruptions on the mucous membranes, and inflammation and swelling of the parotid glands.

It has been ascertained by extensive clinical experience that the minor eruptions are more frequent from the smaller doses of 5 or 10 grains, and that they sometimes disappear when the dose is increased.

Prophylactic measures against the lesions of skin and mucous membranes are great cleanliness of skin and mouth, alkalies, and arsenic. Some think that the sodium iodide is less irritating than the other salts.

Iodide Fever

In a case of plumbism, Oliver reports a temperature of ioi.8° F., and albumin in the urine from 5-grain doses of potassium iodide. In a case of chronic rheumatism of the author's (1912) 10 grains of potassium iodide three times a day caused swelling and intense burning of the face and hands, fever, and eventually delirium. It was learned that the same phenomena had followed iodide the previous year. Konried reports two cases of iodide fever, one of them being from the local use of an ointment. Longcope suggests that there may be a sensitization of the patient by the formation of a new protein out of the drug and the patient's serum.

Chronic iodism is a state in which there are anemia and emaciation, nervousness, tachycardia, and loss of sexual power. Much iodide, even without any poisonous symptoms, tends to lower the body tone and to depress the spirits.


Iodides are believed to be more or less specific in tertiary syphilis and actinomycosis. They do not prevent the development of experimental syphilis. According to Jonathan Hutchinson, "Over the tertiary manifestations of syphilis, the gumma, whether of skin, cellular tissue, coats of arteries, cerebral meninges, or periosteum, potassium iodide exercises almost as definite an influence as mercury over the earlier ones." Fordyce says that iodide has no effect on the early lesions of syphilis, and only a negligible one in rendering the Wassermann reaction negative. It has, however, a profound and physiologic effect on the later lesions. Iodides are also employed in:

Fig. 65.

Fig. 65. - Dermatitis medicamentosa of pustulobullous type, following ingestion of potassium iodide. Principally upon the face, with some pustular lesions on the neck and shoulders. Subsided upon withdrawal of the drug, and recurred on experimental readministration (Stelwagon).

Fig. 66.

Fig. 66. - Dermatitis medicamentosa of a bullous type, from the ingestion of potassium iodide in a woman aged fifty. Face, neck, forearms, and hands involved, and the seat of considerable edematous swelling and variously sized blebs. In some parts blebs became confluent, broke, and uncovered a superficially excoriated surface, as shown in cut. Recovery without any scarring or other trace. Patient had a weak heart (Stelwagon).

1. The asthma of emphysema and chronic bronchitis.

2. Arteriosclerosis and some other conditions with chronic connective-tissue production; not in cirrhosis of the liver or chronic nephritis (unless for arterial hypertension).

3. Aneurysm of the aorta.

4. Cases with arterial tension, from whatever cause.

5. Chronic rheumatism or rheumatoid affections.

6. Poisoning by the heavy metals. Oliver believes them of little or no use in promoting the excretion of metallic poisons, and Gowers states that they increase the poisoning by promoting the solubility of the metal.

7. Colloid goiter - Schondroff calls attention to the good results that have been obtained from iodides and from sea plants containing iodine.

It is generally thought that they should not be used in hyperthyroidism. Krehl advises strongly against their use, as he has seen latent hyperthyroidism change under small doses of iodide into a permanently intractable active form. But Marine and Lenhart (1909) point out that in the hyperplastic glands small doses tend to hasten the change to colloid, which may be desirable. They advise very small doses. There are a number of reports of the development of exophthalmic goiter as the result of iodine medication.


The chief of these is pulmonary tuberculosis.


Potassium or sodium iodide may be given in milk ("best way of all" - Dock), or in saturated aqueous solution, or in dilute solution flavored with compound syrup of sarsaparilla or syrup of orange-peel. Of the saturated solution of potassium iodide in water, 1 minim is practically a drop, as dropped from a bottle mouth or standard dropper, and it contains 1 grain. In syphilis this is often begun by three doses a day of 10 to 15 drops (0.7-1 c.c.), this dose being increased one drop each day until 45 or 60 grains (3 to 4 gm.) of the drug are being taken three times a day. For convenience, compressed tablets may be employed, but they should be dissolved before swallowing, or taken with a large draught of water. Klemperer and others have used sodium iodide intravenously in doses of 1 /4 to 2 1/2 drams (5-10 gm.) two or three times a week.