Side Effects of Iodine Supplements: What They Mean

Get out your pitchforks and get ready to get angry because it’s time to talk about iodine. 

I’m joking (mostly)…

But we actually do need to talk about iodine. 

I’m not sure what it is, but only a few topics in the thyroid world are more controversial than iodine. 

Today we should be sidestepping most of the controversy, though, because we are going to be focusing on the side effects of using this special ingredient. 

When it comes to your thyroid, iodine plays an important role in regulating its function. 

Your body can’t survive without it and yet some people seem to respond negatively when using it. 

The good news is that the reactions that most people experience when using iodine should be positive or non-existent. 

And for those who do experience negative side effects, they can often be avoided or eliminated with the right treatment. 

Today you will learn: 

• What to expect when using iodine supplements
• How iodine impacts your body and triggers various side effects
• What these side effects mean for you
• A huge list of iodine-related side effects
• And how to prevent these side effects from occurring

Let’s jump in…

What Causes Symptoms From Iodine Supplementation?

Before we talk about iodine-related side effects we need to establish baseline facts that will help direct the conversation. 

The first is that all humans require iodine (1) because they can’t produce it on their own. 

The second is that iodine is required for thyroid hormone production (2) and life cannot be sustained without it. 

Therefore, you can draw a connection between iodine consumption and life. 

While these are simple physiologic facts that really can’t be disputed, there are a number of people who experience negative reactions when using iodine. 

And this should come as no surprise. 

If iodine is so critical for life, it makes sense that it may have some impact on the body when using it!

But I want to make clear that the side effects you feel when taking iodine are typically not caused by the iodine itself but due to other issues that were already pre-existing when you took it. 

In this way, iodine is really unmasking other issues that were already there. 

Unfortunately, iodine gets the blame but this isn’t always fair. 

And, for the record, let me point out that the majority of people who take iodine do not notice a perceptible difference in how they feel. 

This happens for about 90% of people who take iodine every day. 

A small fraction, anywhere from 1-10% of people, may experience the negative reactions that we are about to discuss. 

So if that’s you then this information will be helpful. 

There are three main areas where reactions can stem from when you take iodine: 

• The first is changes to thyroid function – This should make sense. Your body needs iodine to produce thyroid hormones (T4 and T3) so you shouldn’t be surprised that taking iodine may impact how much thyroid hormone your body creates! This can be good if you are low on thyroid hormone from hypothyroidism due to iodine deficiency. But it can also be a problem if you take too much iodine and end up overproducing thyroid hormone. Sometimes, taking iodine in the setting of selenium deficiency can lead to thyroid gland inflammation which can impact thyroid hormone production. Changes to thyroid function are a big reason why iodine is often recommended in high doses to people suffering from thyroid conditions. This may not be the smartest thing to do but at least you understand why some people make the recommendation. 
• From detoxification – Because of where iodine sits on the periodic table of elements (next to the noble gases), other elements have a similar electron configuration in their outer shell. This means that iodine, and the other elements on that row, may compete for binding to the same locations. Taking iodine can displace halogens such as chlorine, bromine, and fluorine. When these are displaced your body will sometimes eliminate them through the skin (3) and this is what I mean by detoxification. This will make more sense when we talk about acne when taking iodine. 
• From changes to other hormone systems (sex hormones) – Iodine can also cause symptoms based on its impact on other hormones in the body, especially your sex hormones. Iodine can impact estrogen metabolism (4) and may also indirectly impact estrogen and progesterone through its impact on thyroid function. The result is that you may experience symptoms related to changes in estrogen and progesterone levels when using iodine (this is usually for the better, though). 

Notice when discussing the potential causes of iodine reactions I did not mention iodine allergy. 

That’s because it’s impossible to have a true allergic reaction to iodine (5).

There are many people out there who have been told that they are allergic to iodine when that just isn’t the case.  

This isn’t just my opinion either, researchers have concluded that allergic reactions to iodine are always caused by some other factor as opposed to the iodine itself. 

You can read more about why true iodine allergies do not exist here. 

Symptoms That May Occur When Taking Iodine

With all of this in mind, let’s talk about some of the symptoms that may occur when taking iodine supplements:

#1. Acne-Like Pustules

The first is acne-like pustules. 

The reason we need to use the modifier acne-like is that iodine supplementation does not result in true acne but something that mimics acne. 

It’s well known that iodine supplementation can result in acne-like pustules but what we don’t know is what exactly causes these pustules. 

These pustules are known to be related to halogen elimination (as we discussed above in the detoxification section) but it’s not known if the pustules represent your body eliminating the halogens or if they are just an immune reaction in the skin.

One thing is for sure, though, you don’t want these halogens in your body!

Even though taking iodine may result in something that looks like acne, you should consider this a sign that your body is trying to eliminate something that doesn’t belong. 

I’ve personally seen a lot of patients who take iodine, experience these acne-like pustules, and stop using the iodine. 

This is probably the worst thing you could do!

You want those halogens out of your body because they are interfering with your thyroid, you just need to control how they are being eliminated. 

If you experience acne-like pustules while using iodine then simply slow down on your dose and that should reduce or eliminate the problem. 

Even if you continue at high doses, though, you won’t experience acne forever. 

Eventually, the side effects will wane and you will get all of the benefits of iodine without that particular side effect. 

#2. Racing Heart

Some people may experience a rapid heart rate or a racing heart when using iodine. 

This may or may not be associated with heart palpitations which are the sensation that your heart is beating out of your chest. 

These symptoms tend to be associated with hyperthyroidism (6) and may mean that your iodine supplementation kicks your thyroid into overdrive. 

#3. Sweating

Much like a racing heart, sweating hot flashes, or feeling flushed may be another indicator that your thyroid is in overdrive. 

Sweating is a common symptom of hyperthyroidism. 

#4. Headaches

Sometimes, taking iodine can lead to headaches or migraines. 

It’s not known exactly what triggers headaches from iodine supplementation but is probably due to its impact on thyroid function, blood pressure, or muscle tension. 

#5. Fatigue

If you experience fatigue when taking iodine then it’s most likely related to a change in thyroid function. 

Both hyperthyroidism and hypothyroidism can result in fatigue so you’ll need to do some more digging to figure out which is the cause of your fatigue. 

Low energy can also be associated with adrenal fatigue which is common among patients with thyroid disease. 

#6. Changes to your Weight 

Changes in your weight may be a sign that your iodine supplementation is impacting thyroid function. 

If you notice that you are gaining weight while taking iodine then there’s a good chance that your iodine supplementation is slowing down your thyroid. 

If, on the other hand, you notice that you are losing weight then that may be a sign that you are speeding up your thyroid. 

Speeding up your thyroid for weight loss may not necessarily be a problem though, especially if you have an underactive thyroid. 

Many low thyroid patients experience weight gain from their low thyroid and fixing that low thyroid can result in weight loss. 

Weight loss in the setting of iodine supplementation is really only a big problem when it’s associated with other symptoms of hyperthyroidism such as racing heart, sweating, hot flashes, diarrhea, and so on. 

#7. Nausea

Iodine supplements are usually very well tolerated but taking high doses may result in nausea or stomach pain. 

This is usually from the supplement itself and not from its impact on your thyroid or other hormone systems. 

#8. Stomach Pain

Stomach pain, much like nausea, comes from the iodine supplement itself. 

#9. Metallic Taste in the Mouth

A metallic taste in your mouth may be common when taking iodine supplements because of the flavor of iodine. 

Iodine drops have a sort of metallic salty flavor to them but this flavor is often masked when taking it in a capsule form. 

If you take the capsule form and then experience reflux from your stomach you may taste the iodine. 

This is very similar to what can happen when you take a fish oil capsule and then burp it up later. 

You don’t taste the fish oil when you swallow the capsule but you sure do when you burp it up! 

A metallic taste in the mouth may also be a sign of acid reflux, though, so keep that in mind. 

Acid reflux is quite common among patients with thyroid problems due to the impact that thyroid hormone has on stomach acid (7). 

#10. Joint or Muscle Pain

Joint and muscle pain with iodine supplementation may be a sign that your iodine is impacting thyroid function. 

Joint and muscle pain are often associated with severe states of hypothyroidism (low thyroid function). 

If this occurs, it may be a sign that iodine is blocking how well your thyroid is working and you may need to adjust your dose. 

#11. Changes to your Hair, Skin, or Nails

Both high thyroid function and low thyroid function can impact your hair, skin, and nails. 

And both conditions can make them worse. 

If you take iodine and notice that your hair, skin, and nails are getting better then it’s likely that iodine is improving your thyroid. 

If you notice that your hair, skin, and nails (with the exception of acne as we already discussed) get worse then you may be pushing your thyroid into a hyper or hypo state. 

#12. Thyroid Gland Pain

As I mentioned above, iodine supplementation can result in thyroid gland inflammation. 

If severe, this may result in pain in your thyroid gland. 

Thyroid gland pain is quite rare, even for inflammatory conditions such as Hashimoto’s thyroiditis, though!

It is typically associated with trauma or infection, both of which do not occur very frequently. 

If you notice sensitivity in your thyroid gland (at the base of your neck) you will want to get evaluated by a doctor as soon as possible. 

#13. Swelling in the Neck

Swelling in the neck is a symptom commonly seen in patients who have a thyroid goiter. 

Goiter is just a term used to describe the enlargement of the thyroid gland and doesn’t refer to any specific disease or condition. 

No matter the cause, though, it should be checked out. 

You really do not want your thyroid gland to enlarge for any reason as it may ultimately impair thyroid function. 

Sudden swelling in the neck after taking iodine may indicate thyroid gland inflammation or the triggering of something like autoimmune thyroiditis. 

#14. Other Symptoms of Hyperthyroidism

In addition to some of the symptoms listed here, taking iodine can cause any or all of the symptoms of hyperthyroidism (excess thyroid hormone production). 

For a full list of these symptoms please see this article. 

#15. Other Symptoms of Hypothyroidism

In addition to some of the low thyroid symptoms listed here, taking iodine can cause any or all of the symptoms of hypothyroidism (low thyroid hormone production). 

For a full list of these symptoms please see this article. 

How to Avoid These Side Effects

You can easily avoid the side effects of iodine supplementation by doing a couple of things: 

1. Make sure that you have enough antioxidants before taking an iodine supplement – We know from thyroid physiology that creating thyroid hormone causes the creation of free radicals that can damage the thyroid gland. If you take iodine and stimulate this process but don’t have enough antioxidants to clean up the mess, you may experience problems! Should we blame the iodine for doing its job? No. Instead, we should focus on getting enough antioxidants either through the diet or through supplements to allow iodine to do what it needs to do. One of the biggest antioxidants that you can take to protect your thyroid gland from inflammation is selenium but there are also many others such as glutathione. An easy way to get these antioxidants is by eating plenty of fruits and vegetables. 
2. Take small doses of iodine – Iodine dosing is very much a Goldilocks kind of thing. If you take too much you will cause problems and if you don’t take enough you won’t see any benefit. For some supplements, it’s perfectly fine to take several times the multiple of the RDA (recommended dietary allowance) but this isn’t true of iodine. For best results, stick to iodine doses around the 150 to 300mcg (8) per day range. This will allow you to get the benefits without causing the side effects we have discussed above. You may start to get into trouble when you get to the 1,000mcg per day range or the several grams per day range. 
3. Make sure you aren’t getting iodine from another source – Lastly, before you blame your iodine supplement for causing issues make sure that you count how much iodine you are getting from ALL sources. You may be someone who is getting enough iodine from your diet, in which case, iodine supplements may not be necessary because you already have enough. Iodine can also be hidden in supplements, medications, beauty products, or fortified in processed foods. If you are experiencing the side effects we’ve discussed then look on the back of the bottles of your supplements and medications and start researching ingredients to see if you are accidentally consuming iodine without realizing it. 

Final Thoughts

Even though we just spent a lot of time discussing the side effects of iodine supplements I want to be sure that I reiterate that most people who use iodine will not experience any negative symptoms. 

Most of the time, iodine is very well tolerated and the people who use it actually feel better (not worse)!

If you are one of the few that does feel worse, though, then use the recommendations in this article to help figure out the cause. 

Once you find the cause you should be able to take steps to fix the issue and take iodine without any trouble. 

Now I want to hear from you:

Are you currently taking iodine? 

Have you noticed any of the negative symptoms or side effects listed here? 

Do you know how much iodine you are getting from all sources on a daily basis?

Do you think you are consuming iodine from any hidden sources?

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