Herb & supplement monograph

Iodine Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Iodine interacts with medications. The heart of this page is the interaction list — every drug Iodine is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Iodine is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Iodine Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Iodine drug interaction appears low for most people, because only a small group of thyroid-related medicines is involved. None of the listed interactions are rated major, and the handful that exist are all moderate and share one theme: effects on the thyroid.

Interactions deserving the most attention

The combinations that deserve the most care all involve the thyroid. Amiodarone stands out because the drug itself contains a large amount of iodine, so adding a supplement could push iodine levels too high and upset thyroid function. Lithium can slow the thyroid, and case reports suggest that taking iodine alongside it may add to that effect. Iodine can also work against or unpredictably alter antithyroid drugs, since high doses of iodine can push the thyroid in either direction depending on the person.

What the rest of the list means

Unlike many supplements, iodine's interaction list is short and focused rather than long and theoretical. The evidence comes mostly from case reports and smaller human studies, so these effects are plausible but not firmly proven, and thyroid changes are something routine blood tests can pick up.

Check your medications against Iodine

Based on HelloPharmacist’s Iodine interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Iodine

7 medications have a known interaction with Iodine, graded by severity. Select any drug for the full evidence-based detail.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Iodine using our pharmacist-reviewed interaction data.

AI summaries are generated from our Iodine interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Iodine combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Iodine affects

Every type of medication (drug category) Iodine is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 3 drug categories Iodine interacts with

Amiodarone (cordarone)Antithyroid DrugsLithium

Amiodarone (Cordarone)

Combining iodine with amiodarone might cause excessively high iodine levels.
Amiodarone contains 37.3% iodine and can increase iodine levels. Concomitant use with iodine might increase the risk of having excessive iodine levels and adversely affecting thyroid function. Monitor thyroid function.

Likelihood Probable Evidence D

Antithyroid Drugs

Iodine might alter the effects of antithyroid drugs.
Iodine in high doses has been reported to cause both hyperthyroidism and hypothyroidism, depending on the individual's past medical history. Taking iodine while using antithyroid drugs could alter the effects of the antithyroid drugs.

Likelihood Probable Evidence D

Lithium

Combining iodine with lithium might have additive hypothyroid effects.
Lithium can inhibit thyroid function. Several case reports suggest that concomitant use of lithium and potassium iodide can reduce thyroid function in otherwise healthy adults. Monitor thyroid function.

Likelihood Probable Evidence D

Monograph

Iodine: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

Iodine is an essential mineral your body needs to make thyroid hormones, and most people get enough from iodized salt, dairy, and seafood. Supplements help when you are truly deficient, but taking too much can harm the thyroid, so high-dose products should only be used under medical supervision.

Part used: Mineral (element)
Common forms: Tablets, capsules, liquid drops (Lugol's solution), potassium iodide (KI) tablets, kelp/seaweed supplements, iodized salt

People commonly use it for

Preventing iodine deficiency
Supporting thyroid hormone production
General energy and metabolism support
Cognitive function
Radiation emergency thyroid protection

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

Safe in normal dietary amounts, but high doses can cause thyroid problems.

PregnancyLikely Safe

When used orally and appropriately. Iodine is safe in amounts that do not exceed the tolerable upper intake level (UL) of 1100 mcg daily in those 18 y...

Read the full pregnancy detail

BreastfeedingLikely Safe

When used orally and appropriately. Iodine is safe in amounts that do not exceed the tolerable upper intake level (UL) of 1100 mcg daily in those 18 y...

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

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Overview

Iodine is a mineral that your body cannot make on its own, so you must get it from food or supplements. It is naturally found in seawater, soil, and certain foods such as seafood, seaweed (kelp), dairy products, and eggs. In many countries, iodine is added to table salt (called iodized salt) to help people get enough.

Your thyroid gland uses iodine to make thyroid hormones, which control your growth, metabolism, and energy levels. Because of this, iodine is sold as a dietary supplement on its own and as part of many multivitamins. Common forms include potassium iodide (KI) tablets, liquid drops like Lugol's solution, and kelp-based products.

A lack of iodine is one of the most common nutrient problems worldwide and can cause goiter (an enlarged thyroid) and problems with brain development in children. Adding iodine to salt has greatly reduced these problems in many parts of the world.

How it works

Iodine's main job is to serve as a building block for thyroid hormones (called T3 and T4). The thyroid gland pulls iodine from your bloodstream and combines it with a protein to make these hormones.

Thyroid hormones travel throughout the body and help control how fast your cells work. They affect your metabolism, body temperature, heart rate, growth, and brain development. This is why iodine is especially important during pregnancy and early childhood, when the brain is developing quickly.

When you do not have enough iodine, the thyroid cannot make enough hormone and may enlarge as it tries to work harder, leading to a goiter. Interestingly, taking too much iodine can also disrupt the thyroid, which is why balance matters.

Effectiveness

Does Iodine work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 24 uses evaluated

2 Likely effective 8 Possibly effective 2 Leans ineffective 12 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

Likely Effective Iodine deficiency