Thyroid Science 4(9):R1-5, 2009

www.ThyroidScience.com

Review

Iodine: the Forgotten Weapon
Against Influenza Viruses
David Derry, MD, PhD
332 – 425 Simcoe Street
Victoria BC V8V 4T3
Correspondence: Dr. David Derry dderry@shaw.ca
Received: August 29, 2009
Accepted: September 2, 2009

Abstract. After the 1918 Influenza Pandemic which killed an estimated 30 million people, governments

financed research on the Pandemic’s causes. Over 25 years, influenza viruses were isolated and methods
for killing them with various agents discovered. Iodine was the most effective agent for killing viruses,
especially influenza viruses. Aerosol iodine was found to kill viruses in sprayed mists, and solutions ofiodine were equally effective. In 1945, Burnet and Stone found that putting iodine on mice snouts prevented the mice from being infected with live influenza virus in mists. They suggested that impregnating
masks with iodine would help stop viral spread. They also recommended that medical personnel haveiodine-aerosol-treated rooms for examination and treatment of highly infected patients. Current methodsof dealing with influenza infection are isolation, hand washing, antiviral drugs, and vaccinations. All ofthese methods can be improved by incorporating iodine into them. When impregnated with iodine, masks
become much more effective, and hand washing is more effect when done with mild iodine solutions.
Isolation techniques coupled with aerosol iodine would make them safer for patients, medical personnel,and all persons working with the public. Public health authorities could organize the distribution of iodine
and at the same time educate the public in the effective use of iodine. Oral iodine might also boost bodydefense mechanisms in the upper oral and respiratory mucus. Conclusion: Iodine incorporated into masks,solutions, aerosols, and oral preparations could help to kill influenza viruses and fight off an H1N1 Pandemic.
Keywords. H1N1 • Influenza virus • iodine • aerosols • immunization • isolations • masks • prevention

Influenza Pandemic History

The 1918 Influenza Pandemic killed an estimated 30 million people within a year. In thequarter century following the Pandemic, governments financed intensive research into the Pandemic’s causes and treatments for the viruses thatcause influenza.[1] Iodine was the superior antiseptic that at low concentrations killed the airborne viruses that cause influenza. Iodine waswithout toxicity.[2-12]
The 1918 Pandemic was unusual in that it affected young healthy men, especially soldiers.[1]Normal flu infections are most virulent against
young children and older persons.[14] H1N1 virus
also concentrates its lethality on young healthy persons between ages 5 and 18, as reported by Dr.
Thomas Frieden, director of the U.S. Centers forDisease Control and Prevention.[13-14] In this manner, the H1N1 virus resembles the 1918 virus.
The 1918 virus attacked again in the fall andover two-months killed millions of people. It isanticipated that the H1N1 virus may behave similarly, and public health authorities and the medicalprofession are bracing for this potential outcome.
Treatment and Prevention

The time-tested weapons against influenza
viruses are cleanliness, hand washing, isolation,
masks, immunizations, and antiviral medications.
In 1918, the last two were not available, and theother methods did little to stop viral spread. Washing hands in a standard 70% alcohol solution is effective against most pathogenic bacteria, but it has
no effect on viruses, especially influenza viruses.
In a similar manner, masks used in 1918 showed barely detectable benefits in holding back influenza spread as viruses readily passed throughthe gauze. Isolation is difficult to institute and enforce in cities with large numbers of infectedpatients. In sparsely-populated communities such

2Derry, D.: Iodine: the Forgotten Weapon Against Influenza Viruses

as Alaska, isolation was beneficial but difficult toimplement. Even in hospitals, large numbers ofpatients tend to overwhelm and compromise isolation techniques.[1]Vaccines and antiviral drugs have been prepared and are available in many Western Countries. These interventions are of unknown benefit,
as influenza viruses tend to mutate rapidly.
IodineIodine is the most effective broad-spectrum
antiseptic with low toxicity.[21] Iodine has very highgermicidal activity, and no organism develops resistance to iodine.[12]Iodine has been used in various forms as anantiseptic for the skin, wounds, and mucous surfaces of the body. It has also been used to sterilize
the air and inanimate objects such as catgut andsurgical instruments. Moreover, it has been used asa prophylactic and therapeutic agent in diseases
caused by bacteria, viruses, and fungi, and to sanitize eating utensils.[7,12] Iodine kills bacteria, viruses, fungi, protozoa, and even spores of bacteria andfungi, including anthrax spores. Iodine was usedsuccessfully against influenza, herpes, small pox,and chicken pox viruses.[7]When iodine was suspended in a solution, viralinactivation occurred at dilutions of 1/1,000,000.
Aerosols inactivated many viruses within 30 seconds or less.[7,8,12] Watery solutions such as Lugol’s are the superior germicides.[12]New Findings Leading toEffective Therapy with Iodine

In 1945, a breakthrough occurred when J.D.
Stone and Sir McFarland Burnet (who later went
on to win a Nobel Prize for his Clonal SelectionTheory) exposed mice to lethal effects of influenza
viral mists. The lethal disease was prevented byputting iodine solution on mice snouts just prior toplacing them in chambers containing influenza
viruses.
Burnet and Stone wrote, “As a protection for
doctors, nurses and others dealing with highly infectious patients (Pandemic Influenza) it should be
relatively easy to design a gauze mask partially impregnated with iodine which should offer a greatly
increased degree of protection to the wearer.”[2,3]Burnet and Stone also suggested, “it may be
worth considering iodine vapor as a practical

Thyroid Science 4(9):R1-5, 2009means of limiting indoor infection during an influenza epidemic”[2,3] Students in classrooms wereprotected from influenza by iodine aerosol therapy.
Aerosol iodine also is effective against freshly
sprayed influenza virus.[8]Iodine Body Properties and Distribution

Iodine has been known as a universal antiseptic
for 150 years and has few side effects except inhigh doses. Iodine was introduced into our dietswith iodized salt by David Marine in 1920.[21,26]
This effectively eliminated goiter, cretinism, andmental retardation caused by inadequate iodine inour diet.[21,27,28]
Extremely high doses of iodine can haveserious side effects, but only a small fraction ofsuch extreme doses are necessary to kill influenza
viruses. Iodine circulating in the blood is captured
by many tissue sites and ends up in mucus secretions. The tissues include thyroid and salivary
glands, nasal secretions, stomach, and lungs. Collectively, these tissues and mucus products containfree iodine which defends against invasion bybacteria and viruses.[16,20]
When dietary iodine is absorbed from the gut
all the above sites along with urinary output compete for blood iodine. The most potent competitor
is the thyroid glands, which uses iodine to makethyroid hormone. A constant percentage of dietaryiodine is excreted in the urine.[16]Upper Respiratory andOral Mucus Defenses

The salivary glands, nasal mucosa, and lungs
all secrete mucus which contains iodine.[16] Thelungs not only secrete mucus, but Salter thought
volatile iodine mixes with alveolar air to enter thebronchioles.[17] If this is occurs, it would serve as
an additional barrier to the invading air borneviruses in a manner similar to aerosol iodine.
Stomach mucosa captures iodine from bloodand secretes it into stomach cavities. Free iodine in
the stomach kills bacteria and viruses and it
deactivates biological and chemical toxins. Deadviruses are still immunologically competent andthus antibodies can be made to dead viruses.[20, 22]
Overall, we see there is a complex integrated
system for protecting humans from viral or bacterial invasions via oral, nasal, and gastrointestinal
routes.[16] This system depends on taking adequateDerry, D.: Iodine: the Forgotten Weapon Against Influenza Viruses

iodine orally.
Current Iodine Doses andDoses Needed to Prevent Invasion

Our current recommended iodine intake by theWHO is 150 to 200 micrograms daily. This dosefirst started by David Marine in 1920 has successfully prevented goiters, cretinism, and mental retardation.[21] If the daily iodine dose is above 3 mg
for over 2 weeks, the thyroid gland becomes saturated and no longer takes up much iodine.[25]Then, dietary iodine goes to other sites namedabove and is excreted into the upper respiratoryand gastrointestinal tract mucus.[16] It seems logicalthat air borne viruses become stuck in mucus andkilled by free iodine.
Dietary iodine found in iodized salt is below
the amounts needed to fill mucus defense roles. To
protect themselves, people wishing to boost theirdefense against infections should supplement theirdiets with iodine in the form of Lugol’s. Most people will probably be protected by an amount of
Lugol’s that provides the average amount of iodine
ingested by Japanese populations for centuries.
This amount is about 12 mg daily. Two drops of
Lugol’s daily in the liquid of their choice will provide 13 mg.
Lugol’s Iodine Solution

Lugol’s iodine solution was discovered byHenri Lugol, a Paris physician,[21] more than 150
years ago. It has been used therapeutically sincethen. Lugol’s consists of 5% free iodine and 10%
potassium iodide in water. Lugol’s has a distinct
advantage over most other iodine oral medications
by having a high level of free iodine, which is theactive ingredient that kills viruses.[5,6,15]
Medical personnel and others interacting withhighly infectious persons should consider protecting themselves with 2 drops daily of Lugol’s iodine
orally in the liquid of their choice, as all liquids
work. At this dose, no noticeable side effects occur.
Free iodine is believed to react with the aminoacids tyrosine and/or histidine at low concentrations. The reaction denatures proteins and causes
the death of cells.[5,6,20,22] In Canada, Lugol’s iodine
solution can be bought over the counter and costs
about 10 dollars for 100 ml. This amount will last
one person 5 years.

Thyroid Science 4(9):R1-5, 2009

3Iodine Well Tolerated by Humans

With few exceptions, humans tolerate welllarge doses of iodine.[18-24,29] High doses are not required to kill viruses. Aerosols can be effective insterilizing a room at levels not detectable by humans.[7,4,8,12] In the 1930s, iodine’s use therapeutically was stated in the US Pharmacopeia. The
usual dose for treatment is 300 mgs (46 drops ofLugol’s) to 1 gm (1000 mg, 154 drops). The maximum safe dose in 24 hours should seldom exceed
6 gm as at these extreme doses iodine is not without danger. Such high doses are not needed to prevent or treat influenza virus infections.
Educating the PublicSupervised by Public Health Officials and physicians the lay public can be taught ways to use iodine. By using iodine correctly persons could protect themselves and their families. Stock piled concentrated solutions can be the source of more dilute
solutions for distribution to the public.[7,12]
Can Lugol’s be Given toTreat Influenza Infection?

The author is not aware of any published dataon treating viral infections with oral or intravenous
Lugol’s solution or any other medications with theexception of some topical iodine’s use for herpes
infections. As Lugol’s is well tolerated both ways,
it is a form of treatment that could be explored. It
was standard practice to give high doses of iodine
for Graves’ disease prior to thyroidectomy and noserious side effects were noticed.[24]Why Did the Japanese not Fair
Better in the 1918 Influenza Pandemic?

A possible explanation for Japanese citizens
doing as badly as the rest of the world in 1918 isthat in Japan, as well in Chile, citizens have thehighest consumption of nitrates in the world. Nitrates in high doses competitively block membranetransport mechanisms that move iodine from theblood into the thyroid gland, salivary glands, andstomach mucus glands. This nitrate effect wouldinterfere with body defense systems. No opportunity has arisen to test this possibility.
Pre-planning in Catastrophes

Hard, fast, and exacting rules for preventing an
Influenza Pandemic cannot be laid down. However,4

Derry, D.: Iodine: the Forgotten Weapon Against Influenza Viruses

definite, prearranged, overall systematic planningis necessary. All possible methods of prevention
and intervention should be taken into consideration
so that the greatest amount of good to the largest
number of people results.[12]The methods using iodine are untried in pandemic conditions. It is likely that trying the methods during pandemic will present new problems.
Nor are these proven methods of protection, as no
epidemic has been tested this way. However, data
reviewed here indicate that this approach, done
properly, could help arrest an epidemic and possibly save many lives, especially those of medical
personnel, from this horrible disease.
For stock piling, it is more economical to store
a supply of a mixture of iodine and a soluble iodide
in glass bottles. The bottle sizes should be such as
to make quickly available solutions of desired concentrations of free iodine without the necessity ofweighing at the time of use. In this form thegermicide shelf life is indefinite.[12]Conclusion

A medical literature review indicates the 1918
Influenza Pandemic was caused by viruses. In addition, iodine, as iodine solutions or aerosols, wassuperior in every respect to kill the flu viruses.
These findings indicate that simple methods could
help with the fight if an epidemic occurs.
Many forms of iodine have been available, but
Lugol’s iodine has stood the test of time and is
standardized around the world. Lugol’s has advantages. It has a high free iodine content, which suggests it may be a choice agent for fighting influenza virus. Using iodine has not been tried, butavailable data strongly suggests it should help.
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