What are the symptoms of iodine toxicity?

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Last updated: March 9, 2025View editorial policy

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From the Guidelines

Iodine toxicity symptoms include abdominal pain, loss of appetite, metallic taste in mouth, coughing, fever, delirium, diarrhea, gum and tooth soreness, and vomiting, as evidenced by the most recent study in 2022 1. These symptoms can occur due to various sources of excessive iodine, such as iodinated contrast agents, topical iodine disinfectants, or chronic intake of amiodarone. Some key points to consider:

  • Chronic exposure to excess iodine intake can induce autoimmune thyroiditis and lead to hypothyroidism and goiter 1.
  • Iodine-sufficient individuals are more likely to experience elevated blood concentrations of TSH, lower levels of thyroid hormones, and increased thyroid autoimmunity with excess iodine intake 1.
  • Clinical signs of toxicity can vary, but common symptoms include gastrointestinal issues, such as abdominal pain, diarrhea, and vomiting, as well as systemic symptoms like fever and delirium 1.
  • It is essential to note that the upper level of iodine intake is 300 mg per day, and exceeding this amount can lead to toxicity 1. Key considerations for patients at risk:
  • Patients with pre-existing thyroid conditions or those taking certain medications should be cautious about iodine intake.
  • Individuals exposed to prolonged povidone iodine disinfection or topical application should be monitored for signs of toxicity.
  • Discontinuing iodine intake and providing supportive care are crucial in managing iodine toxicity.

From the FDA Drug Label

SIDE EFFECTS: ... Possible side effects include: ... allergic reactions Allergic reaction can include ... fever with joint pain ... trouble breathing, speaking or swallowing ... Taking iodide, in rare cases, may cause overactivity of the thyroid gland, underactivity of the thyroid gland, or enlargement of the thyroid gland (goiter). Symptoms of an overactive thyroid gland may include an irregular heart beat and chest pain. The symptoms of iodine toxicity from potassium iodide (PO) may include:

  • Allergic reactions such as skin rashes, swelling, fever with joint pain, and trouble breathing
  • Thyroid gland problems including:
    • Overactivity of the thyroid gland with symptoms like irregular heart beat and chest pain
    • Underactivity of the thyroid gland (hypothyroidism)
    • Enlargement of the thyroid gland (goiter) 2

From the Research

Symptoms of Iodine Toxicity

The symptoms of iodine toxicity can vary depending on the severity and duration of exposure. Some common symptoms include:

  • Gastrointestinal symptoms, such as those experienced by a patient who ingested a substance suspected to be methamphetamine, which contained iodine 3
  • Hypotension and tachycardia, resulting from hypovolemia 3
  • Tachypnea, or rapid breathing, as seen in a patient who presented with suspected methamphetamine ingestion 3
  • Chills and fever, also reported in the case of suspected methamphetamine ingestion 3
  • Vision loss, as a result of retinal toxicity caused by high doses of iodate 4
  • Thyroid dysfunction, including hypothyroidism and hyperthyroidism, which can be induced by excessive iodine intake 5, 6
  • Death, in severe cases of oral ingestion of iodine 7

Systemic Symptoms

Systemic symptoms of iodine toxicity can include:

  • Hypovolemia, leading to hypotension and tachycardia 3
  • Elevated serum creatinine and liver function tests, as seen in a patient with suspected methamphetamine ingestion 3
  • Narrow anion gap, indicating potential iodine toxicity 3

Ocular Symptoms

Ocular symptoms of iodine toxicity can include:

  • Bilateral vision loss, resulting from retinal toxicity 4
  • Damage to the retinal pigment epithelium (RPE), ellipsoid zone (EZ), and interdigitation zone (IZ), as observed in a patient who ingested pure iodine 4
  • Hypoautofluorescence areas, detected by fundus autofluorescence (FAF) findings 4

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Acute iodine toxicity from a suspected oral methamphetamine ingestion.

Clinical medicine insights. Case reports, 2014

Research

Bilateral retinal toxicity as a result of poisoning with pure iodine.

Romanian journal of ophthalmology, 2021

Research

[Iodine-induced thyroid dysfunction].

Medizinische Klinik, Intensivmedizin und Notfallmedizin, 2021

Research

Death by oral ingestion of iodine.

Emergency medicine Australasia : EMA, 2005

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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