A Letter to the Editor titled Iodine, a preventive and curative agent in the COVID-19 pandemic? was published online in the journal Medical Hypotheses on May 23, 2020. The authors write:
“we hypothesize that iodine… could be the magic bullet for fighting the COVID-19 pandemic, in both a curative and preventive way… it is important to conduct studies as soon as possible, especially because this possible new treatment is simple, inexpensive and safe.”
An essential nutrient and universal disinfectant
Iodine is an essential nutrient, and well-known disinfectant, with an over 200-year history of use in medicine. A paper titled Infectious Disease Management and Control with Povidone Iodine states the following:
“For over 60 years, povidone iodine (PVP-I) formulations have been shown to limit the impact and spread of infectious diseases with potent antiviral, antibacterial and antifungal effects… PVP-I mouthwashes and gargles significantly reduce viral load in the oral cavity and the oropharynx. The importance of PVP-I has been emphasized by its inclusion in the World Health Organization’s list of essential medicines, and high potency for virucidal activity has been observed against viruses of significant global concern, including… Middle-East Respiratory Syndrome (MERS) and Sudden Acute Respiratory Syndrome (SARS) coronaviruses.”
More recent studies have shown that iodine solutions (in the form of povidone-iodine) are also effective at inactivating SARS-CoV-2, the virus responsible for COVID-19. A paper titled Rapid In-Vitro Inactivation of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Using Povidone-Iodine Oral Antiseptic Rinse concludes:
“PVP-I oral antiseptic preparations rapidly inactivated SARS-CoV-2 virus in vitro. The viricidal activity was present at the lowest concentration of 0.5% PVP-I and at the lowest contact time of 15 seconds.”
Research shows that povidone iodine, even at low concentrations, quickly inactivates SARS-CoV-2 in a laboratory setting. Furthermore, preliminary studies in humans suggest that povidone iodine mouthwash can reduce the salivary viral load of SARS-CoV-2 in patients with Covid-19, potentially reducing transmission and improving outcomes in infected patients.
Can iodine treat Covid-19?
Given the above research findings, it seems reasonable to ask: Can iodine be used to treat Covid-19?
Researchers in Pakistan decided to test this hypothesis in (Rhesus macaque) monkeys. Their preprint paper (not yet peer-reviewed) is titled An assessment of efficacy of Iodine complex (Renessans) against SARS-CoV-2 in non-human primates (Rhesus macaque). The researchers gave a group of monkeys an iodine complex dosed at 2.85 mg per 7 kg of body weight. Another group of monkeys served as the control group. The monkeys were then infected with SARS-CoV-2. The researchers found that monkeys who received the iodine treatment cleared the virus considerably more quickly than those who did not receive iodine (nasal swabs of iodine-treated monkeys were negative 2 weeks after being infected, whereas untreated monkeys still had positive nasal swabs 3 weeks after infection).
Moreover, one week after being infected, SARS-CoV-2 was detected in the internal organs (intestine, lungs, heart, trachea) of an untreated monkey, but no SARS-CoV-2 was found in the internal organs of monkeys who received the iodine treatment. Furthermore, gross pathological lesions were less severe in the iodine-treated monkeys compared to the monkey in the control group, suggesting that the iodine complex had antiviral activity and helped in the early recovery of monkeys who received the iodine treatment.
Where is the clinical evidence?
As I write this at the end of 2020, more than a year after the introduction of SARS-CoV-2, I am not aware of a single human clinical trial that has been published on iodine as a treatment for Covid-19 (despite the promising aforementioned animal and laboratory studies). Currently, the only published clinical study I am aware of that used iodine to treat Covid-19 patients is a paper titled A Novel Approach to Treating COVID-19 Using Nutritional and Oxidative Therapies. This study was an observational case series that documented over a hundred Covid-19 patients who were treated with:
- Vitamin D, vitamin A, and vitamin C
- A nebulized solution of dilute hydrogen peroxide and iodine
About one-third of patients also received intravenous vitamin C, intravenous hydrogen peroxide, and intramuscular ozone. On average, patients reported being completely better one week after starting the treatment protocol. Out of 107 total Covid-19 patients, there was only one hospitalization during treatment, and zero deaths. The study authors write:
“A novel treatment program combining nutritional and oxidative therapies was shown to successfully treat the signs and symptoms of 100% of 107 patients diagnosed with COVID-19.”
It is difficult to tease out the precise effect that iodine had on the success of this treatment protocol, given that high-dose vitamins and oxidative therapies were used concurrently alongside iodine supplementation. It is worth noting that the Covid-19 patients in this study received 25 mg/day of iodine in the form of Lugol’s solution for four days beginning at the first sign of symptoms. Additionally, patients were instructed to add one drop of 5% Lugol’s solution to their normal saline nebulizer solution.
The Recommended Dietary Allowance (RDA) for iodine is currently set at 150 micrograms and the Tolerable Upper Intake Level is 1.1 milligrams (1,100 micrograms) per day for adults. For perspective, a 25 mg dose of iodine would be nearly 23 times above the upper limit. High doses of iodine should only be taken under medical supervision. In particular, infants, the elderly, pregnant and lactating women, and individuals with preexisting thyroid conditions can be especially susceptible to adverse effects of excess iodine intake and exposure. Be sure to work with a healthcare practitioner to determine the right amount of iodine for your individual circumstances.