As an essential nutrient, iodine is needed for thyroid function, and a deficiency is linked to higher risk of thyroid and stomach cancers. Some evidence shows that treatment with molecular iodine before breast cancer surgery may improve tumor response and reduce some side effects.

Safety and precautions

Cancer risk

“Excess iodine intake may be an unfavorable factor in breast cancer.”1He S, Wang B et al. Iodine stimulates estrogen receptor singling and its systemic level is increased in surgical patients due to topical absorption. Oncotarget. 2017 Sep 4;9(1):375-384. See also a discussion of modes of action of iodine on breast cancer in Are you a health professional? ›

Some evidence also links high levels of iodine in urine to higher levels of thyroid cancer, although the authors of a large study concluded that high urinary iodine is a specific characteristic of papillary thyroid cancer but not a cause. In this analysis, cancer risk was not related to regional iodine intake.2Yan AR, Zhang X et al. Urinary iodine is increased in papillary thyroid carcinoma but is not altered by regional population iodine intake status: a meta-analysis and implications. Endocrine Journal. 2019;66(6):497-514. Higher levels of iodine in the diet were linked to higher incidence of thyroid cancer in the area around Lahore, Pakistan, but only among rural residents and not urban residents. The authors did not report the comparative intake of iodine between rural and urban areas or the proportions of people who may have iodine deficiency or excess in either area. We know only that dietary levels of iodine that are too high are linked to higher risk of thyroid cancer, but this study does not tell us what level is “too high.”3Asif F, Noor-Ul-Amin M, Jabeen R. Identification of thyroid cancer risk factors incidence in urban and rural areas, Pakistan. Pakistan Journal of Pharmaceutical Sciences. 2020;33(6):2607-2610.

The antiseptic use of iodine during breast surgery leads to significantly higher urinary iodine levels for about two days among people undergoing breast surgery compared to other people, although any connection to cancer risk was not investigated.4He S, Wang B et al. Iodine stimulates estrogen receptor singling and its systemic level is increased in surgical patients due to topical absorption. Oncotarget. 2017 Sep 4;9(1):375-384. 

Urinary iodine concentration did not show a link to the prevalence of BRAFV600E mutation, which is related to several types of cancer in a large study.5Lin YY, Hsieh YS. Iodine nutritional status is not a direct factor in the prevalence of the BRAFV600E mutation in papillary thyroid cancer. Archives of Endocrinology and Metabolism. 2023;67(2):172-178.

Also see evidence of higher risk of thyroid cancer among people with an iodine deficiency in How can iodine help you? What the research says ›

Side effects

High intake of iodine can cause health risks related to the thyroid gland:6Office of Dietary Supplements. Iodine Fact Sheet for Health Professionals. National Institutes of Health. May 1, 2020. Viewed May 6, 2020.

  • Hyperthyroidism
  • Goiter
  • Thyroiditis
  • Thyroid cancer

Some people are intolerant of, or sensitive to, iodine in chemical agents such as radiocontrast agents used for x-rays, in iodine-containing disinfectants like Betadine, or even in foods. If you suspect you have an iodine allergy, you can ask your doctor for diagnostic tests. Anyone with an allergy or sensitivity should make sure that all their medical professionals are aware of an iodine allergy before medical treatment.7Cadman B. What is an iodine intolerance? Medical News Today. April 3, 2018. Viewed May 6, 2020.

Overdose can result in acute poisoning symptoms:8Office of Dietary Supplements. Iodine Fact Sheet for Health Professionals. National Institutes of Health. May 1, 2020. Viewed May 6, 2020. 

  • Burning of the mouth, throat, and stomach
  • Fever
  • Abdominal pain
  • Nausea
  • Vomiting
  • Diarrhea
  • Weak pulse
  • Coma

People with autoimmune thyroid disease and iodine deficiency may be more susceptible to overdose and may have side effects even when taking iodine doses considered safe for the general population.9Office of Dietary Supplements. Iodine Fact Sheet for Health Professionals. National Institutes of Health. May 1, 2020. Viewed May 6, 2020.

Interactions with medications

Iodine can interact with many medications. Before taking an iodine supplement, consult your physician regarding safe use. Consult your pharmacist to check for any medications or supplements that may interact with iodine.

Helpful link

Patrick L. Iodine: deficiency and therapeutic considerations. Alternative Medicine Review. 2008 Jun;13(2):116-27.

Keep reading about iodine


Nancy Hepp, MS

Lead Researcher
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Ms. Hepp is a researcher and communicator who has been writing and editing educational content on varied health topics for more than 20 years. She serves as lead researcher and writer for CancerChoices and also served as the first program manager. Her graduate work in research and cognitive psychology, her master’s degree in instructional design, and her certificate in web design have all guided her in writing and presenting information for a wide variety of audiences and uses. Nancy’s service as faculty development coordinator in the Department of Family Medicine at Wright State University also provided experience in medical research, plus insights into medical education and medical care from the professional’s perspective.

Nancy Hepp, MS Lead Researcher

Laura Pole, MSN, RN, OCNS

Senior Clinical Consultant
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Laura Pole is senior clinical consultant for CancerChoices. Laura is an oncology clinical nurse specialist who has been providing integrative oncology clinical care, navigation, consultation, and education services for over 40 years. She is the co-creator and co-coordinator of the Integrative Oncology Navigation Training at Smith Center for Healing and the Arts in Washington, DC. Laura also manages the “Media Watch Cancer News That You Can Use” listserv for Smith Center/Commonweal. In her role as a palliative care educator and consultant, Laura has served as statewide Respecting Choices Faculty for the Virginia POST (Physician Orders for Scope of Treatment) Collaborative as well as provided statewide professional education on palliative and end-of-life care for the Virginia Association for Hospices and Palliative Care.

For CancerChoices, Laura curates content and research, networks with clinical and organizational partners, brings awareness and education of integrative oncology at professional and patient conferences and programs, and translates research into information relevant to the patient experience as well as clinical practice.

Laura sees her work with CancerChoices as a perfect alignment of all her passions, knowledge and skills in integrative oncology care. She is honored to serve you.

Laura Pole, MSN, RN, OCNS Senior Clinical Consultant


Susan Yaguda, MSN, RN

Manager at Atrium Health’s Levine Cancer Institute and CancerChoices Clinical Consultant
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Susan Yaguda, MSN, RN, has been a nurse for nearly 40 years, working in a variety of healthcare settings. She currently works in Charlotte, North Carolina, at Atrium Health’s Levine Cancer Institute as the manager for Integrative Oncology and Cancer Survivorship. She works with a multidisciplinary team to deliver holistic, evidence-based support and education for patients and care partners at any point along the trajectory of cancer care. She completed the Integrative Oncology Scholars Program through the University of Michigan in 2020, is certified as an Integrative Health Coach through Duke Integrative Medicine and has a post-graduate certificate in Nursing Education from the University of North Carolina, Charlotte. Susan also was awarded the Planetree International Scholar’s Award in 2018 and was recognized by the Daisy Foundation for Nurse Leadership in 2021. Susan has a particular interest in empowering patients and care partners with knowledge to help drive informed decision making and educating nurses on the benefits of integrative care for patients and self-care. She has presented nationally and internationally on integrative oncology and nursing education.

She and her husband, Mark, have two adult children and a very spoiled foxhound. She enjoys hiking, knitting, cooking, and pickleball.

“As a frequent consumer of Beyond Conventional Cancer Therapies, and now CancerChoices, for both professional education and patient support, it is an honor to have the opportunity to engage with the dedicated team at CancerChoices to serve those impacted by this disease.”  


Susan Yaguda, MSN, RN Manager at Atrium Health’s Levine Cancer Institute and CancerChoices Clinical Consultant

Last update: May 7, 2024

Last full literature review: April 2023

We are grateful for research support from Adriana Gutierrez Galvis.

CancerChoices provides information about integrativein cancer care, a patient-centered approach combining the best of conventional care, self care, and evidence-informed complementary care in an integrated plan cancer care. We review complementaryin cancer care, complementary care involves the use of therapies intended to enhance or add to standard conventional treatments; examples include supplements, mind-body approaches such as yoga or psychosocialtherapy, and acupuncture therapies and self carelifestyle actions and behaviors that may impact cancer outcomes; examples include eating health-promoting foods, limiting alcohol, increasing physical activity, and managing stress practices to help patients and professionals explore and integrate the best combination of conventionalthe cancer care offered by conventionally trained physicians and most hospitals; examples are chemotherapy, surgery, and radiotherapy and complementary therapies and practices for each person.

Our staff have no financial conflicts of interest to declare. We receive no funds from any manufacturers or retailers gaining financial profit by promoting or discouraging therapies mentioned on this site.

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