Potassium Iodide: A Decades-Long Therapy For Asthma

150 micrograms (mcg) is the RDA for adults. This can be purchased for about $10 over-the-counter.

This is an old article. 1964. 58 years ago.

The Asthma-Suppressive Action Of Potassium Iodide, Journal of Allergy, May-June 1964

It describes a benefit from treatment with iodine in the form of potassium iodide:

The exceptional asthma-suppressive action of potassium iodide is described as observed in ten cases among approximately two hundred treated with this drug. A high degree of control of asthma may persist for prolonged periods, up to five years. The degree of effectiveness may be such that prolonged steroid therapy can be avoided. The data suggest that this is not a placebo effect.

Potassium iodide was in general well tolerated, but its side effects warrant consideration and their management is discussed. Thyroid adenoma was the most important complication of therapy. Iodide, long considered to possess some anti-inflammatory action, appears to exert little benefit on other common allergy syndromes. It did not diminish either immediate or delayed allergic skin test reactions. The mechanism of the asthma-suppressive action of iodide remains obscure. What accounts for the peculiar iodide-responsiveness of certain cases of bronchial asthma constitutes a related provocative problem.

These cases are nothing short of remarkable.

This is the kind of claim that the medical industry and drug companies would rather see lost to the ages since it would cut into profits from doctor visits, inhalers, and prescription medications. Potassium iodide is cheap and can be purchased over-the-counter.

I should say that the amount of potassium iodide they took was several times the RDA. That could come with unwanted side effects:

Adverse Reactions to Iodide Therapy of Asthma and Other Pulmonary Diseases, Pediatrics, 1 February 1976

First, the supportive news:

Five current textbooks advocate the use of iodides in chronic asthma.1-5 “Iodide compounds have a stimulating effect on bronchial secretions and represent expectorants of major importance in treating asthma and particularly status asthmaticus.”2


Dosage recommendations usually are 300 mg of potassium iodide every two hours in adults1 and 60 mg per year of age four times daily in children.4 These dosage recommendations are many times greater than the 65 mg of organic iodine (T4 and T3) which the average human thyroid gland delivers to the circulation per day, or the estimated daily adult iodide requirement of 200 mg of iodide.8 As a matter of fact, these recommended dosages for iodides represent 10 to 30 times the total body content of iodide!

I’m pretty sure in that last paragraph the authors are referring to micrograms (mcg) not milligrams (mg).

The NIH says adults shouldn’t take more than about 1000 micrograms (mcg) a day, with 150-200 mcg being the RDA, as stated above. In the case studies at the top of this post, patients were taking a half to several grams potassium iodide a day!

In sum: Potassium iodide has been documented as a cheap, simple, over-the-counter therapy for symptoms of asthma. However only some people are responsive and it may require a (perhaps prohibitively) high dose to be effective.

An aside: I just love the way older studies are written:

What accounts for the peculiar iodide-responsiveness of certain cases of bronchial asthma constitutes a related provocative problem.

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