Iodine Dosage Guide
Recommended daily intake by age and gender — based on NIH Dietary Reference Intakes.
Our assessment
Based on the data, iodine is essential for health, but the margin between adequate intake and excess is narrow. The most important safety finding is that getting too much iodine can cause the same symptoms as deficiency, including goiter (an enlarged thyroid gland), as well as thyroid gland inflammation and thyroid cancer NIH ODS ↗. This paradoxical effect requires careful monitoring.
Safety profile
Specific side effects from high iodine intake include: burning of the mouth, throat, and stomach; fever; stomach pain; nausea; vomiting; diarrhea; weak pulse; and coma NIH ODS ↗. These effects are associated with very large doses (several grams). Data on the exact number of adverse event reports from the FDA data provided is not available; the provided data does not include FDA report counts FDA FAERS ↗.
How it works
Iodine is a critical component of thyroid hormones, which regulate metabolism, growth, and development NIH ODS ↗. The data indicates that both deficiency and excess iodine can disrupt thyroid function, leading to conditions like goiter and thyroid inflammation NIH ODS ↗.
Our recommendation
Be cautious with supplementation. The daily upper limits for iodine include intakes from all sources NIH ODS ↗. Those taking antithyroid medications such as methimazole (Tapazole) should be especially cautious, as high doses of iodine with these medications could cause interactions NIH ODS ↗. If you have a thyroid condition or are on thyroid medication, consult a healthcare provider before taking iodine supplements NIH ODS ↗.
AI-assisted analysis. Data sourced from NIH ODS.
Understanding RDAs
Dietary Reference Intakes (DRIs) are a set of reference values used to plan and assess nutrient intakes of healthy people. They include:
- RDA (Recommended Dietary Allowance) — The average daily intake sufficient to meet the nutrient requirements of nearly all (97-98%) healthy individuals.
- AI (Adequate Intake) — Established when evidence is insufficient to develop an RDA. Based on observed nutrient intake by healthy people.
- UL (Tolerable Upper Intake Level) — The maximum daily intake unlikely to cause adverse health effects. Exceeding the UL increases the risk of toxicity.
Values vary by age, gender, and life stage (pregnancy, lactation).
Source: National Academies of Sciences, Engineering, and Medicine
Recommended Dietary Allowance
| Life Stage | Recommended Amount |
|---|---|
| Birth to 6 months | 110 mcg |
| Infants 7–12 months | 130 mcg |
| Children 1–8 years | 90 mcg |
| Children 9–13 years | 120 mcg |
| Teens 14–18 years | 150 mcg |
| Adults | 150 mcg |
| Pregnant teens and women | 220 mcg |
| Breastfeeding teens and women | 290 mcg |
Source: National Academies of Sciences, Engineering, and Medicine