Thyroid Supplement Side Effects: What to Expect

Thyroid Supplement Side Effects: What to Expect

Why Thousands of Thyroid Patients Use Thyroid Support Supplements

Look, I’m definitely a little bit biased here because I sell thyroid supplements (over 80,000+ thyroid patients have used them to date) but I always get a chuckle when I hear how conventional doctors talk about them. 

On one hand, they will tell you that they don’t work, they are a waste of your money, and that you should never take them. 

On the other, they will tell you that they are unregulated, that they will interfere with your thyroid medication, and that they will make you feel worse

some people suggest that thyroid supplements aren't safe
some doctors recommend avoiding thyroid supplements

The first situation implies that they don’t work at all while the other implies that they are too powerful to be controlled.

So which is it?

Well, it all depends. 

As usual, there is some truth to what your doctor is telling you but it’s not the whole truth. 

There are some thyroid support supplements that can lead to problems and there are others that may not help you at all. 

Whether they work or not depends on what type of thyroid support supplement you are taking, the ingredients in the supplement, the quality of the manufacturing process, and where they were manufactured. 

If you get the right type of thyroid support supplement then, yes, there is a chance that you will see improvement in how you are feeling. 

If you use the wrong one or a low-quality cheap thyroid support supplement, well, then, yes, you are probably just throwing your money away. 

The key is to use the right one. 

But to suggest that all thyroid support supplements are harmful or dangerous is just silly. 

And when you look at the numbers, you will see why. 

There are literally hundreds of thousands of thyroid patients who purchase thyroid support supplements on a monthly basis. 

You may even be one of them if you are reading this. 

Do you really think hundreds of thousands of thyroid patients continually buy things that don’t work or don’t provide any benefit?

I don’t either. 

I trust that when a thyroid patient purchases a supplement and then continues to buy it over and over again that they are getting some benefit from it. 

That’s been my experience and that’s what I’ve seen over the years as I’ve helped thousands of thyroid patients. 

But doctors aren’t all wrong. 

There can be some side effects associated with thyroid support supplements so let’s discuss those in more detail. 

Today you will learn:

  • A list of potential positive and negative side effects that can be caused by thyroid supplements
  • How to do your best to prevent negative side effects (so you can only get the good ones that you are looking for)
  • Why some thyroid supplements can interfere with your thyroid medication and cause problems for you and your doctor
  • How to take your thyroid supplements in conjunction with your thyroid medication to avoid problems
  • And much more

Let’s jump in…


Foods to Avoid if you Have Thyroid Problems:

I’ve found that these 10 foods cause the most problems for thyroid patients. Learn which foods you should avoid if you have thyroid disease of any type.


The Complete List of Thyroid Lab tests:

The list includes optimal ranges, normal ranges, and the complete list of tests you need to diagnose and manage thyroid disease correctly!


List of Thyroid Supplement Side Effects to Watch out For:

Whenever you take anything, whether that be a supplement or a medication, you should be thinking about side effects. 

Side effects aren’t always bad, by the way. 

When you take ibuprofen for a headache, for instance, the side effect you are looking for is a relief in your pain. 

What you aren’t looking for is an upset stomach (1), which can certainly come when taking NSAIDs like ibuprofen on an empty stomach.

ibuprofen can cause intestinal bleeding

This same logic applies to thyroid supplements. 

You are taking them because you want to feel better. 

You want to have more energy, you want to lose weight, you want your hair to grow, you want your brain fog to lift, you want to feel happier, and so on. 

Thyroid patients are drawn to thyroid support supplements because their medication doesn’t always take away their low thyroid symptoms

So people go out looking for alternatives and then land on thyroid support supplements. 

This is perfectly fine as long as those supplements give you what you want while also avoiding the side effects that you don’t want. 

With this in mind, let’s talk about some potential good side effects of thyroid supplements before we talk about the bad ones. 

Positive Side Effects

Because your thyroid helps to control and regulate just about every cell in your body, the impact that boosting thyroid function has on your body is pretty broad. 

In fact, two people can take the exact same supplement and experience completely different benefits. 


Because no two people with thyroid disease are exactly alike

Your symptoms will differ from the next person and that’s completely fine and normal. 

Some potential good side effects you may experience while taking thyroid supplements include: 

  • More energy (very common)
  • Reduced brain fog
  • Some weight loss
  • Reduced hair fall and/or new hair growth
  • Warmer body temperature
  • Improved resting heart rate
  • Lighter mood
  • Improved sense of well-being (you just feel better overall)
  • Reduced joint pain and/or muscle aches
  • More regular menstrual cycle

The presence of these side effects indicates that your thyroid supplements are working and doing exactly what you want them to do. 

But, unfortunately, because not all thyroid supplements are created equal, you may end up feeling worse.

Negative Side Effects

Negative side effects occur when the supplements you are taking make your thyroid worse, cause a reaction in your body to a specific ingredient, or when they result in what is referred to as a detox-like reaction (2). 

the definition of the herxheimer reaction and how it relates to the use of certain supplements

Most of the time, these negative side effects are not a good sign and may mean that you need to change up what you are taking, try a new supplement, or recheck your thyroid gland. 

Sometimes, though, thyroid supplements can make you temporarily feel worse for a short period of time and this isn’t a problem. 

This occurs with the so-called detox-like reaction I mentioned above. 

join 80000 thyroid patients

Sometimes taking powerful supplements can accelerate the release of things that you don’t want in your body (think chemicals or toxins) which can make you feel worse temporarily. 

But this is a good thing because you don’t want those things there anyway. 

And sometimes, you just need to give your body time to acclimate to something new. 

It can be hard to tease out sometimes which is why working with a professional is always ideal. 

Here are some negative side effects that thyroid patients may experience when taking thyroid supplements: 

  • Headache
  • Worsening fatigue
  • Itching of the skin
  • Acne
  • Flushing or warm rushes
  • Uncomfortable heart palpitations
  • Tremors or shaking of the hands
  • Changes to your appetite
  • Sensitivity to heat
  • New rashes or hives
  • Raised body temperature or a slight fever
  • Shortness of breath
  • Decreased sense of well-being (feeling overall worse)
  • Indigestion or stomach pain
  • Changes to bowel movements

The presence of these side effects indicates that your body is not tolerating your supplements very well and that they may be having a negative impact on your thyroid

I mentioned above that sometimes you may feel worse before you feel better. 

If that’s the case, your negative side effects will persist only for about 5-7 days which is the period it takes for your body to acclimate to your new supplements. 

If you are experiencing side effects that last longer than this, it’s a good idea to stop taking whatever you are using and either try something new or give your body some time to readjust back to normal. 

Preventing Negative Side Effects from Thyroid Supplements

The key to taking thyroid supplements is to do whatever you can to enhance the positive side effects while decreasing or eliminating the chances of negative side effects. 

After all, what thyroid patient doesn’t want to have more energy and feel better?

Most if not all. 

But they don’t want to experience stomach aches, acne, or headaches in the process! 

And no one is blaming them for that. 

By following the guidelines before you choose to purchase or buy a thyroid supplement, you will give your body the best chance it has to feel better (not worse). 

#1. Avoid Taking High Doses of Iodine

One key ingredient that may cause problems in thyroid supplements is that of iodine. 

Iodine is a critical and essential element required for thyroid function so it makes sense that it is commonly found in these supplements. 

When you consider that many thyroid patients are knowingly (and unknowingly) avoiding iodine, there is certainly a place for including it. 

The problem with iodine doesn’t stem from the iodine itself but from the dose that you are taking. 

Regular doses of iodine, found in the RDA range of about 150 to 300mcg of iodine (3) per day, are generally very safe and well-tolerated. 

Recommended dietary intake of iodine for adults ages 19 and older

But some thyroid supplements contain doses much higher than this. 

Sometimes you will find doses of iodine in the range of 25mg or more which is hundreds of times more potent than the recommended daily dose. 

Very high doses of iodine can cause a blockade of the uptake of thyroid hormone into your thyroid gland and may also precipitate autoimmune thyroid disease (Graves’ disease and Hashimoto’s have both been linked to very high doses of iodine (4)). 

the association between iodine intake and autoimmune thyroid disease

This doesn’t mean you need to avoid any thyroid supplement that has iodine but you should be aware of the dose. 

You can check the supplement fact panel on the back of your supplement bottle to see if iodine is included. 

If it is, you will see the type of iodine found as well as the dose. 

Unfortunately, it’s not always that simple. 

Because iodine is found in foods, your supplement may just state that it includes something like dulse or kelp. 

Iodine is naturally found in these sources but may not be included in the supplement fact panel if that’s the case. 

Just be aware of this because sometimes thyroid supplements will contain kelp and may not state that iodine is in there even though it’s found in the kelp. 

When you are first starting with thyroid support supplements aim to keep your iodine intake from all sources around 150 to 300mcg per day. 

This will keep you out of trouble. 

#2. Avoid Unlabeled Thyroid Hormones

The next thing you want to do is avoid taking unlabeled thyroid hormones that are sometimes found in thyroid support supplements. 

What do I mean by unlabeled thyroid hormones?

Exactly as it sounds. 

There are 4 thyroid hormones that your body creates from the thyroid gland. 

T1, T2, T3, and T4. 

T3 and T4 thyroid hormones are considered prescription medications and are only available if your doctor writes you a prescription for something like levothyroxine (T4) or liothyronine (T3). 

T2 (5) is available over the counter in supplement form and T1 isn’t talked about much because we aren’t exactly sure how important it is. 

T1 and T2 are not as powerful as T4 and T3 which is why these are only available in a prescription

Because of how powerful T4 and T3 are, you really need to know exactly how much you are taking. 

Unfortunately, studies (6) have shown that many thyroid support supplements contain these powerful ingredients which are not labeled on the supplement fact panel. 

some thyroid support supplements contain active T4 and t3 thyroid hormones

Whether this is done intentionally (to get away with providing a prescription quality supplement without FDA oversight) or unintentionally (because of poor manufacturing) isn’t clear. 

But we do know that taking these ingredients can be a problem. 

I’m not against the idea that thyroid patients can learn and understand how to self-dose or self-titrate medication but it can become a big problem when you aren’t told how much you are taking and if the dosing changes from one lot to another!

Taking unlabeled thyroid hormones can cause changes to your thyroid labs, make dosing your prescription medications unpredictable, and lead to hyperthyroid symptoms if you aren’t careful. 

You can avoid these ingredients by sticking to supplements that are manufactured in the United States and looking for manufacturers that third-party test their ingredients for purity and ingredient content. 

This should help you stay safe and avoid taking an unknown amount of powerful thyroid hormone. 

#3. Don’t Take Your Thyroid Supplements at the Same Time as Your Medication

Next, you should be aware of the impact that thyroid supplements can have on your thyroid medication. 

Not the medication itself but how well it is absorbed by your body. 

You should think about your thyroid medication and your thyroid supplements as complementary to one another and not as a replacement. 

Thyroid supplements can help your thyroid medication work more effectively and they can pick up where medication is falling short. 

In order to facilitate this, you better make sure you are taking them both correctly!

Lots of things can negatively impact thyroid medication absorption (7) which is why you should always take your medication by itself (and never with your thyroid supplements). 

various factors which negatively impact levothyroxine pharmacokinetics

I’ve found that taking thyroid support supplements 30 to 60 minutes away from your thyroid medication is sufficient as long as you aren’t taking a calcium or an iron supplement. 

These ingredients should be taken 4 hours away from thyroid medication

If you take your thyroid supplements and thyroid medication at the same time, you may feel worse because your thyroid medication is no longer working as effectively as it once did

This isn’t the fault of the supplements necessarily, but more about how and when you are taking them. 

#4. Start Low and Go Slow

Finally, because thyroid function is so important to your overall health, it’s never a bad idea to take it slow. 

Your thyroid helps to control and regulate many systems in the body and these systems all have an impact on how you are feeling day to day. 

For this reason, many doctors like to start out on small doses of thyroid medication and slowly increase your dose over time. 

You can apply this same principle to thyroid support supplements. 

Even if the recommended dose of your thyroid support supplement is 2 capsules per day there’s nothing stopping you from starting with 1 capsule and increasing up to 2 capsules after a week or two. 

When in doubt, start low and go slow with your thyroid supplement dose! 

Final Thoughts

I’m a big believer in the use of thyroid supplements because I’ve seen them provide tremendous benefits to thousands of patients over the years. 

Even though they can be helpful, there are certainly some bad ones out there that can cause problems. 

The key to using thyroid supplements successfully is to avoid the ingredients that can cause problems, to take your supplements correctly, and never use them as a replacement for your thyroid medication. 

Following these general principles should help you maximize positive side effects while minimizing negative side effects. 

Now I want to hear from you:

Are you currently taking thyroid supplements?

Are you experiencing any negative side effects? What about positive side effects?

Have you had a bad reaction in the past?

Does your doctor recommend using supplements or have they told you to stay away from them?

Leave your questions or comments below! 








positive and negative side effects of thyroid supplements

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About Dr. Westin Childs

Hey! I'm Westin Childs D.O. (former Osteopathic Physician). I don't practice medicine anymore and instead specialize in helping people like YOU who have thyroid problems, hormone imbalances, and weight loss resistance. I love to write and share what I've learned over the years. I also happen to formulate the best supplements on the market (well, at least in my opinion!) and I'm proud to say that over 80,000+ people have used them over the last 7 years. You can read more about my own personal health journey and why I am so passionate about what I do.

P.S. Here are 4 ways you can get more help right now:

#1. Get my free thyroid downloads, resources, and PDFs here.

#2. Need better symptom control? Check out my thyroid supplements.

#3. Sign up to receive 20% off your first order.

#4. Follow me on Youtube, Facebook, TikTok, and Instagram for up-to-date thyroid tips, tricks, videos, and more.

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