Should You Be Taking Iodine for Your Thyroid? (Spoiler: Probably Not Much)
- Jun 18, 2025
- 5 min read
Updated: Nov 11, 2025
If you hang out in thyroid Facebook groups for more than 30 seconds, you’ll probably see someone say that iodine (specifically Lugol’s iodine) completely cured their thyroid issues.
Three drops a day! No more meds! Energy through the roof!
And while I wish it were that simple, it’s unfortunately not. Iodine is essential for thyroid hormone production, but if you have Hashimoto’s or any autoimmune thyroid condition, more iodine isn’t always better. In fact, it can sometimes make things worse.
Let’s break down what the research actually says.
What Iodine Does
Iodine is a trace mineral your thyroid uses to make T3 and T4. (The “3” and “4” refer to how many iodine atoms are attached to each hormone.) So yes, you definitely need some iodine. But the thyroid is a Goldilocks organ; it doesn’t like too little, and it definitely doesn’t like too much. It wants just right. Most of us are already getting plenty from food.
More Iodine Isn’t Always Better (Especially with Hashimoto’s)
Excess iodine can actually trigger or worsen autoimmune thyroid disease.
Too much iodine increases thyroglobulin, a protein that the immune system often targets in Hashimoto’s (that's the TgAB on your bloodwork). It can also cause oxidative damage inside the thyroid, especially if you're low in selenium. Countries that added iodine to their food supply (like Denmark and Sri Lanka) actually saw more thyroid autoimmunity after iodization programs, not less. Sudden increases in iodine can trigger thyroid shutdown. This is known as the Wolff–Chaikoff effect. In healthy individuals, the thyroid typically 'escapes' this effect and resumes normal hormone production after a few days. But in people with autoimmune thyroid conditions like Hashimoto’s, that escape mechanism may not function properly, leading to longer-term suppression of thyroid activity.
But I Feel Better on Lugol’s?
If someone was truly deficient in iodine, they might feel better after starting it. But that doesn’t mean everyone should jump on board with 3 drops a day. One drop of 2% Lugol’s iodine contains about 2.5 mg of iodine. That’s over 16 times the Recommended Daily Allowance (RDA), which is just 150 mcg per day for most adults. Three drops? That’s 50 times the RDA. Beyond the RDA, we can look at the TUL (Tolerable Upper Intake Level or Limit). It’s the maximum daily amount of a nutrient that’s considered safe for most people to take long-term, without increasing the risk of adverse health effects.
For iodine, the TUL for adults is 1,100 micrograms (mcg) per day, or 1.1 milligrams.
This includes iodine from all sources: food, supplements, and iodized salt.
So just one drop of 2% Lugol's exceeds the TUL (by 227%).
Going above the TUL occasionally isn’t always harmful, but regularly exceeding it (especially in people with autoimmune thyroid conditions) can lead to thyroid dysfunction, inflammation, or hormone imbalances.
Excess iodine doesn’t just impact the thyroid. Research has linked high iodine intake to increased autoimmune activity, as well as higher rates of thyroid cancer, breast cancer, and cardiovascular diseases like hypertension and atherosclerosis. This is largely due to the oxidative stress, inflammation, and endothelial dysfunction it can trigger. There's also emerging evidence that it may contribute to neurotoxic diseases, which is one more reason to rethink the idea that "a few drops can’t hurt.”
Are You Actually Iodine Deficient?
Probably not. If you eat processed foods or restaurant meals, you’re almost certainly getting iodized salt. Even if you cook everything at home, common foods contain iodine.
1/4 tsp iodized salt (78 mcg)
1 cup plain yogurt (84 mcg)
3 oz cod (146 mcg)
1 large egg (31 mcg)
2 slices of enriched white bread (296 mcg)
2 tbsp of flaked nori seaweed (116 mcg)
If you eat a fairly typical diet, odds are you’re not deficient.
If you’re using unrefined sea salt at home, it may contain trace amounts of iodine (but not enough to meet daily needs). Most sea salts are not iodized unless it says so on the label, so don’t count on them as a reliable source. Also, many multivitamins contain at least some Iodine, so check labels on all your supplements to see if you're getting some there.
Testing Iodine Levels: How to Know If You Actually Need More
Guessing isn’t the way to go here, especially when excess iodine can backfire.
Testing options include:
Urinary iodine concentration (UIC): reflects recent intake.
RBC iodine: offers a more stable view of iodine status.
Hair Tissue Mineral Analysis (HTMA): long-term trends can be calculated, but not definitive.
You can also look at thyroid bloodwork for indirect signs.
In the U.S., you can even order your own labs without a doctor through companies like Ulta Labs (click the link to order now if you're curious - they usually offer 20% off your first order and partner with Quest so it's easy to find a draw location). A blog post about common lab tests you may want to run is in the works, so check back soon!
What to Do If You Are Low
If you do turn out to be iodine-deficient, start with food, not mega-dosing:
Add iodized salt to home cooking
Include more seafood, dairy, or eggs
Consider a kelp-based supplement at a moderate dose (under 225 mcg/day)
Make sure you’re also getting selenium, zinc, and iron
If you are histamine-sensitive: seaweed and kelp supplements can be histamine liberators for some people (either from the iodine itself, naturally occurring amines, or environmental contamination). If you notice symptoms like flushing, itching, air hunger, or dizziness, it’s worth pressing pause and digging deeper.
As I mentioned above, many multivitamins already contain iodine (usually around 150 mcg, which meets the RDA for adults). On top of that, supplements labeled as “thyroid support” often include kelp or iodine in much higher doses, so they’re not meant to be taken long term without testing. Layering these on top of dietary sources can quietly push you into excess, so make sure you're checking ALL supplements.
As always, consult your doctor before changing or adding to your supplement routine. This information is for educational purposes only and is not a substitute for medical advice.
What About Iodine on Your Skin?
Some people say your body only absorbs what it needs if you paint iodine on your skin. This is not true. Yes, iodine does absorb through the skin, and studies show it can raise blood and urine iodine levels significantly. Absorption isn’t self-regulated. Your body doesn’t just stop absorbing when it’s had enough. The fading of the patch is mostly due to evaporation, not absorption. This method isn’t reliable for testing, and repeated use may lead to overload, especially in people with Hashimoto’s or MCAS.
TL;DR
If iodine cured Hashimoto’s, we’d all be cured.
For most people with autoimmune thyroid issues, high-dose iodine isn’t the answer. Testing, supporting nutrient status, reducing inflammation, and looking at the full picture of your health is what moves the needle.
Grab my free Histamine & Hormones Guide to learn how histamine, hormone shifts, and nutrient depletion affect your thyroid.
If you like what you’re learning here, you’ll love the conversations happening inside my free Facebook group, Find Your Balance. Come join us!
Check out my Back to Balance program if you want to dig deep (like this blog post on steroids) into every aspect of Hashimoto’s and learn to the exact steps to figuring out what your unique body needs to calm the autoimmune attack and finally feel better. Here's a quick video walkthrough so you can see exactly what's included.
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Disclaimer: I do not diagnose, treat, prevent, or cure any disease or condition. Nothing I share with my clients is intended to substitute for the advice, treatment or diagnosis of a qualified licensed physician. I may not make any medical diagnoses or claim, nor substitute for your personal physician’s care. It is my role to partner with you to provide ongoing support and accountability in an opt-in model of self-care and any changes should be done under the supervision of a licensed physician.
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