Hashimoto’s Flare Up Symptoms: Signs Your Thyroid Is Inflamed

Hashimoto’s Flare Up Symptoms: Signs Your Thyroid Is Inflamed

What Are Hashimoto’s Flare-Ups?

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You might think of Hashimoto’s like a static disease. 

A disease that causes a set of symptoms that you have to live with for the rest of your life. 

This couldn’t be farther from the truth. 

On one hand, Hashimoto’s is actually a dynamic disease, one that changes and fluctuates over time. 

On the other, it’s also a disease that can progress and worsen but also one that can be tamed (if you know how to manage it). 

As a result, it’s not uncommon for Hashimoto’s to cause ups and downs and result in changes to your symptoms. 

At times, you may notice that certain things trigger your Hashimoto’s and make your symptoms worse. 

This is known as a Hashimoto’s flare-up and is well documented. 

Why are flare-ups important?

Because their presence indicates more damage and inflammation in your thyroid gland!

While this is obviously not something you want to occur, there is some silver lining. 

The silver lining is that flare-ups can help you identify triggers that make your Hashimoto’s worse. 

If you can identify these triggers and then avoid them, you will go a long way to improving the outcome of your disease and the health of your thyroid. 

Make sense?


Because we are about to jump into the symptoms of a Hashimoto’s flare-up. 


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How to Tell If You Are In a Hashimoto’s Flare-Up: 

Before we get started you need to be aware of a few important points. 

The first is that even though everyone reading this has Hashimoto’s, the symptoms that each of you may experience during a flare-up will differ. 

This means that one of you may experience more fatigue during your flare-up while another patient may experience weight gain or neck pain during theirs. 

This is completely normal and nothing to worry about. 

What’s more important is identifying the symptoms that commonly are associated with YOUR flare-up. 

Second, you will probably experience multiple flare-ups throughout your life. 

Don’t be surprised as you go through the symptoms below to find that you’ve probably already experienced several flare-ups throughout your life. 

Even though flare-ups are common, they aren’t a good thing. 

Your goal should be to spend as little time as possible in a flare-up. 

Third, when you experience these symptoms your next step should be to go to your doctor to get your thyroid labs tested

You will want to get both your thyroid antibodies tested as well as your thyroid function tested. 

We will discuss these tests in more detail at the end. 

With this information in mind, let’s talk about what a Hashimoto’s flare-up looks like. 

#1. Sudden or unexplained weight gain

As we dive into these symptoms you will probably notice that you are already dealing with many of them. 

Unfortunately, due to how doctors treat thyroid patients, that isn’t uncommon. 

When we talk about flare-ups it’s important to realize that a flare-up usually causes a sudden worsening of a thyroid symptom that already exists. 

What do I mean?

Imagine that your thyroid is already causing some weight gain (which is the first symptom we are going to be talking about today). 

Weight gain is a very common symptom of hypothyroidism (low thyroid function) and something that many patients with Hashimoto’s deal with

A flare-up won’t make you slowly gain weight, instead, it will cause a sudden worsening of an already damaged metabolism. 

So if you are someone who is already, let’s say, 20 pounds overweight and then suddenly, out of the blue, you gain 10 more pounds, that’s probably a sign of a flare-up. 

This is assuming that you are making no changes to how active you are or to the food that you are eating during this time period. 

The weight gain associated with a flare-up needs to be unexplained. 

In other words, you can’t blame that weight on anything except your thyroid. 

Unfortunately, weight gained during a flare-up often stacks on top of the weight you already had before the flare-up. 

And this weight usually doesn’t go away when the flare-up is managed (unlike many of the other symptoms we will soon discuss). 

For this reason, weight gain as a symptom of a flare-up should be taken very seriously and addressed as soon as possible

Why does weight gain occur?

Because as your thyroid becomes inflamed (from the flare-up), thyroid function slows down which results in a slowing of your metabolism

The slower your thyroid the slower your metabolism (1). 

#2. Sudden or worsening fatigue

Next up is a sudden change in your energy levels. 

As a patient with Hashimoto’s, you are probably well accustomed to living with some level of baseline fatigue

Whether that’s from your thyroid directly or from its impact on your adrenals, fatigue is another very common symptom (2) of Hashimoto’s. 

If you notice that your fatigue suddenly gets a lot worse, without noticing any changes to your sleeping patterns, then it may be a sign you are in a flare-up. 

#3. Heat in the neck or thyroid gland area

Some patients with Hashimoto’s report that they feel heat in the neck over the area of their thyroid gland when they are in a flare-up. 

This heat is most likely the result of increased inflammation in the thyroid gland which occurs during the flare. 

Heat is always produced when there is inflammation present, the degree of that heat just depends on the degree of inflammation. 

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I’m sure you’ve all had an infection on your skin or a bug bite that feels hot to the touch. 

That heat is a sign of inflammation. 

Since your thyroid gland is under the skin, it’s more difficult to feel heat produced by the gland itself, but it’s still present for some people. 

Under no circumstance is it normal for your thyroid to ever feel hot!

So this is one of the symptoms that always means something is wrong. 

#4. Thyroid pain (uncommon but can occur)

Rarely, some patients may also experience thyroid gland pain during a flare-up. 

Because of the way that the thyroid gland is innervated, it’s actually pretty rare for your thyroid gland to ever experience “pain”. 

Pain in the thyroid gland itself typically occurs with trauma or with an infection of the gland (called subacute thyroiditis (3)). 

But just because it’s rare doesn’t mean it can’t happen with Hashimoto’s. 

There have been some case reports (4) of patients experiencing pain in their thyroid gland with Hashimoto’s. 

If you do experience this symptom, though, make sure you get it checked out because it may be a sign of something worse

#5. Difficulty swallowing or feeling pressure in the neck while talking/eating/drinking

This symptom is quite common and occurs frequently during flare-ups. 

As the thyroid gland enlarges (due to inflammation) it can press on the surrounding structures in your neck. 

Your thyroid gland sits underneath your larynx (your voice box) and in front of your trachea (your breathing tube). 

The esophagus sits behind both of these structures. 

It’s not hard to imagine that there just isn’t a lot of extra space in this area of your neck. 

So when something enlarges or gets inflamed and grows in size, it presses on the surrounding objects. 

If your thyroid gland presses on your larynx then it may cause hoarseness or a change in your voice (this can also come directly from changes in thyroid function (5)).

If your thyroid gland grows outward then it will feel like your skin is getting tighter and you will feel pressure (6) at the base of your neck. 

If your thyroid gland pushes backward, then it will make swallowing, eating, and drinking more difficult. 

These are all signs that your thyroid is enlarged, which can definitely occur due to inflammation. 

Normally, these symptoms are not a huge deal because the thyroid can only enlarge so much.

Rarely, though, they can become a big problem and may require immediate medical attention, especially if they are interfering with your ability to breathe. 

#6. A general feeling of weakness or malaise

Because a flare-up is really a problem with your immune system, you may experience some symptoms that mimic illnesses. 

When you get sick with something like a viral illness, it’s not uncommon to just feel weak or puny compared to your normal healthy self. 

Weakness or a general feeling of malaise is typical of viral infections. 

These symptoms can also be associated with a Hashimoto’s flare-up. 


A flare-up is a sign that your immune is increasing its attack on your thyroid gland. 

It’s the same immune system that responds to infections, it’s just directed at your thyroid gland instead of a pathogen. 

What you may not realize is that many of the symptoms you experience when you are sick come from your body trying to fix the problem. 

For this reason, there will be some spillover of symptoms when your immune system is activated for either an autoimmune disease or when protecting your body from a virus or bacteria. 

#7. New joint pain and/or muscular pain (or worsening of existing pain)

This is another one of those symptoms that patients with Hashimoto’s deal with at baseline. 

Changes to thyroid function may result in muscle (7) or joint pain. 

Patients experiencing a Hashimoto’s flare-up often experience a worsening of pain in their joints or muscles. 

This symptom typically occurs in people who already had joint or muscle pain before the flare-up, but it can be a new symptom for some patients as well. 

It can be particularly difficult to treat but you can learn more about what causes chronic pain in thyroid patients here

#8. New racing heart or sensation of heart palpitations

Most of the symptoms we’ve discussed so are associated with low thyroid function which is most common when you experience a Hashimoto’s flare-up. 

As inflammation ramps up in the thyroid gland during a flare-up it typically causes a slowing down of thyroid function. 

But it can do more than just that. 

Sometimes inflammation in the thyroid gland can result in increased release of thyroid hormone and symptoms associated with excess thyroid hormone. 

A racing heart and palpitations are typically seen when this happens. 

As thyroid hormone rushes into your system and into your heart, you may experience heart palpitations as your heart beats harder and faster (8). 

This can result in a rapid heart rate but it doesn’t have to. 

Sometimes you just feel the sensation of your heart beating even when your heart rate is normal. 

If you are feeling the sensation of your heart beating make sure you count your beats per minute. 

If it’s less than 80 or 90 beats per minute then you are not experiencing a rapid heart rate. 

#9. Jittery sensation or uncomfortable rush (or nervous energy)

Jittery sensations, nervous energy, or an uncomfortable rush are also associated with the excess release of thyroid hormone from your thyroid gland. 

These symptoms can make it difficult to sleep, may result in a slight tremor of your hands, and make relaxing very difficult. 

They aren’t very common with a flare-up but they can occur. 

#10. Abrupt onset of brain fog, difficulty concentrating, or inability to focus on difficult tasks

Just like other areas of your body, your thyroid can impact how well your brain functions. 

When this happens, it’s usually manifested as brain fog

It can be difficult to think of the words that you want to use when speaking, it can be hard to concentrate on tasks, you may find yourself uninterested in difficult work, and so on. 

Why this occurs is not well known but it’s probably because your thyroid impacts neurotransmitters and neuron function in other ways. 

While we don’t know exactly why it happens, we do know that it can get worse during a flare-up!

So if you notice a worsening of these symptoms then that may be an early sign you are in a flare-up. 

#11. Changes to your gut function (usually constipation but can also be diarrhea)

The function of your gut can be used as an indirect measure of thyroid function. 

When your thyroid is working as intended you shouldn’t experience changes in stool frequency. 

When your thyroid slows down you may experience constipation (9) and when your thyroid speeds up you may experience loose stools or diarrhea. 

Flare-ups can be associated with both because it depends on whether or not your flare-up is slowing down your thyroid or speeding it up. 

The only downside to this symptom is that many other factors can influence your stools as well!

For instance, it’s much more likely that changes in your diet will impact your stooling frequency compared to your thyroid. 

You can differentiate between diet-related stool changes and thyroid-related stool changes by looking at your other symptoms. 

If you are experiencing increased weight gain, weakness, worsening brain fog, AND constipation, then that constipation is probably from your thyroid. 

If you just experience constipation without any other symptom then it’s probably related to something else (such as your diet). 

#12. Acute symptoms of hyperthyroidism (rare)

I won’t include all of the symptoms of hyperthyroidism here but you should know that flare-ups can result in any or all of the symptoms of hyperthyroidism. 

This is not very common, though, as a flare-up is typically short-lived and usually slows down the thyroid. 

#13. Acute symptoms of hypothyroidism (common)

Flare-ups can also cause any or all of the symptoms of hypothyroidism. 

I won’t list them all here but you can see a full list of low thyroid symptoms here. 

You are probably already very familiar with these symptoms because many thyroid patients continue to experience them even when taking thyroid medication. 

What To do If you are in a Flare-up?

This is all good information to have but what are you supposed to do about it? 

I mentioned previously that knowing you are in a flare-up is valuable but it’s only valuable if you do something about it!

If you let your flare-up fester and get worse then you are just allowing your condition to get worse over time. 

And, believe me, you really don’t want to allow Hashimoto’s to permanently damage your thyroid gland. 

If you find yourself in a flare-up based on your symptoms above then here are some steps you should think about taking (sooner rather than later, I might add): 

  • Get a full list of thyroid lab tests including thyroid antibodies and inflammatory markers – The first thing you’ll want to do is get a full set of thyroid lab tests to evaluate how well your thyroid is working. This will help you determine if you actually are in a flare and whether or not that flare is impacting your thyroid function. You should also get your thyroid antibodies tested as well (TPO antibodies and thyroglobulin antibodies). In many cases, thyroid antibodies will increase during a flare-up. In addition to these tests, it’s also helpful to get some basic inflammatory markers such as CRP and ESR. These are often elevated in a flare-up. 
  • Try to identify the trigger of your flare-up – If possible, take stock of what happened to you around the time of your flare-up. Were you under more stress? Did you change your eating habits? Were you recently sick with a virus or a bacterial infection? Were you exposed to environmental toxins? All of these, and more, can be potential triggers of a flare-up. Identifying the trigger of your flare can help you determine your next step… (Note: it’s not always possible to identify the trigger of a flare-up but that shouldn’t stop you from trying some basic treatments). 
  • Use therapies and treatments to get yourself out of your flare-up as quickly as possible – The next thing you’ll want to do is undergo treatments and therapies to fix whatever triggered your flare-up. If that’s stress then you can use stress relaxation techniques. If the cause was toxins then detoxification protocols may be helpful. If the case was related to your diet then removing the offending foods would be in order. Even if you aren’t sure what caused your flare-up then doing basic things like eating cleanerexercising regularly, ensuring you get enough sleep, taking basic supplements, and so on, are almost always helpful to some degree. 
  • Retest your labs to confirm a reduction in inflammation after using therapies – Finally, once you’ve undergone these treatments and therapies for several months you can recheck your thyroid lab tests including your antibodies and inflammatory markers. If your therapies are working then you should see a normalization of your thyroid function, a reduction in thyroid antibodies, and a reduction in inflammatory markers. 

Final Thoughts

A Hashimoto’s flare-up is something that just about every patient with Hashimoto’s will experience at some point in their life. 

The key is to understand when it happens so you can immediately take steps to try and fix it. 

One of the best things you can do is simply be aware of the symptoms associated with a flare. 

That way, when you experience these symptoms you know you need to take additional steps such as getting tested and trying to identify the trigger. 

Now I want to hear from you: 

Do you think you are in a flare-up right now based on your symptoms? 

Have you experienced a Hashimoto’s flare-up before?

If so, what kind of symptoms did you experience?

Were you able to find out your trigger?

Did you get your thyroid labs checked? 

Leave your questions or comments below! 

#1. ncbi.nlm.nih.gov/pmc/articles/PMC4044302/

#2. ncbi.nlm.nih.gov/pmc/articles/PMC8217009/

#3. ncbi.nlm.nih.gov/books/NBK279084/

#4. ncbi.nlm.nih.gov/pmc/articles/PMC7003982/

#5. ncbi.nlm.nih.gov/pmc/articles/PMC6592446/

#6. ncbi.nlm.nih.gov/books/NBK285557/

#7. ncbi.nlm.nih.gov/books/NBK519513/

#8. ncbi.nlm.nih.gov/pmc/articles/PMC4318631/

#9. ncbi.nlm.nih.gov/pmc/articles/PMC2699000/

signs you are in a hashmoto's flare up

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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 6 years. You can read more about my own personal health journey and why I am so passionate about what I do.

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