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A Thyroid Flare Up or ‘Bad Thyroid Day’

A Thyroid Flare Up or 'Bad Thyroid Day'
Originally published on 12th May 2016
Last updated on 25th July 2021

I refer to days when my hypothyroid or Hashimoto’s symptoms are particularly bad as a ‘bad thyroid day’. Also called ‘flare ups’, I’ve had these days when my thyroid condition hasn’t been under control and when it has.

My Hashimoto’s is currently in remission, yet I can still experience them from time to time. 

Even now, with optimal TSH, Free T3 and Free T4 levels, as well as low thyroid antibody levels, I can still have flare ups.

What Is a ‘Flare Up’?

A Hashimoto’s or thyroid flare up is defined by an increase in symptoms of the thyroid condition usually due to one of the causes listed below. A flare usually lasts for a few days to a few weeks.

However, if you’re feeling that they’re going on much longer than this, it could actually not be a flare up, but a permanent dropping of your thyroid hormone levels. After all, flare ups are not associated with a drop in thyroid hormone levels, but are more a reaction to overexertion which takes your body a day or two to recover from. Read more here.

Some people call an increase in thyroid antibody levels (after having them low for quite some time) a flare up. And others also use the term to describe a change in thyroid levels. I tend not to. I think this is confusing!

Symptoms can differ from person to person, though the most commonly reported in a flare up are:

Related post: Thyroid Patients Explain How Their Flare Ups Feel

What Causes a Flare Up?

These are the most common triggers according to thyroid patients:

  • Drinking alcohol
  • Eating poorly (such as a lot of sugary or processed food, not giving your body good nutrition)
  • Consuming a known food allergen or sensitivity (such as gluten, dairy, soy etc.)
  • Overexertion (mentally and/or physically) – See the spoons post
  • Stress
  • Not sticking to a good sleep routine
  • Viral, bacterial, fungal etc. infections
  • Being on your period or due to start on your period (hormone fluctuations)
  • Pregnancy

I asked the thyroid community to share the many causes of their flare ups here.

If you’re stuck in flare up cycles, it may be because you’re doing something like this:

  1. Over exercising
  2. Doing all the things
  3. Running yourself in to the ground tired
  4. Forced to stop exercising and running around because your body collapses
  5. Forced to rest and recuperatet
  6. Repeat over and over again

So in order to prevent more flares, we need to break this cycle!

How Can I Avoid Flare Ups in Future?

Each time you experience one, try to pinpoint what things (such as those listed above) have contributed to it. Obviously the main thing to do here is then avoid them in future if possible, so as to reduce the chances of another flare.

Some people find relief from flare-ups when they eliminate a food allergy or sensitivity, such as gluten. Around 90% of people with hypothyroidism have the autoimmune disease Hashimoto’s, which is the cause for their hypothyroidism. [1]

Many don’t even know it, though, and for these people, cutting out gluten from their diet is often cited to help control thyroid antibodies and ease symptoms, helping them reduce the amount of future flare ups.

You can also look at quieting the immune response by lowing your thyroid antibodies if you have Hashimoto’s, which can even lead to the condition being in remission. By lowering thyroid antibodies, we’re told that this puts the condition under control and means it is better managed, reducing symptoms and flare ups. See this article for ways to do this.

Supporting your immune system and body as a whole with good nutrition, supplements such as Vitamin C, D and Selenium, adequate sleep and keeping stress levels low can also help.

Ensuring you are also addressing any adrenal dysfunction is also very key, as adrenal fatigue (though it is more accurately referred to as hypothalamic-pituitary axis dysfunction) often goes hand in hand with hypothyroidism and can cause many of the same symptoms.

Having your thyroid levels tested regularly and ensuring they are all optimised is also key to feeling well with thyroid disease.

What Should I Do in a Flare Up?

First and foremost, it is important to say that if you’re feeling incredibly unwell, then you should always see your doctor in case something more serious is going on. If what you initially think is a flare up actually carries on for weeks or months, it is probably more likely a sign of a thyroid medication dosage adjustment or need for other investigations.

How To Manage Flare Ups When They Happen

The bad thyroid days are a part of having hypothyroidism that I have learnt to accept with time, but I did, at one point, think I would be able to make a 100% recovery back to full health, without any flare ups ever again. But you know what? No one person is in perfect health every single day of their lives. And so it’s perfectly normal to expect flare ups in symptoms from time to time.

Now I realise it’s OK and normal to have bad health days. My health is always going to require close monitoring to try and keep it on track as much as possible.

As thyroid patients, we do often expect a bit too much from ourselves, too. And I’m very guilty of this!

On a bad thyroid day or flare up day, I like to rest, keep warm, put on some films or a TV boxset, and drink lots of warm drinks such as hot water and lemon, or herbal tea, keeping myself well hydrated. I eat nourishing food, enjoy bone broths and might even call a friend or two for some company. But if I don’t feel sociable, then that’s OK too.

I listen to my body and let it have whatever it needs to get over this flare. I often like to try and get in the bath (if I have the time) as this helps my body loosen up, but hot water bottles can also really help with this too.

On days where I have had to work or otherwise didn’t have the luxury of just resting in front of the TV or in bed, I have compromised. I can try to limit how much work or other commitments impede my recovery from a flare up. For example, seeking permission to work from home, working altered hours until the flare has passed, replacing walking to and from work with transport to save energy, or otherwise speaking to my line manager about suitable adjustments. 

If making changes surrounding my work isn’t an option, at the very least I can support  recuperating outside of work as much as possible. I limit how much unnecessary activity I do and maximise resting and recuperation time instead. Learn to say “no”. I avoid sugar and caffeine and other stimulants that place additional stress on the endocrine system, and eat nutrient dense food to nourish me and aid my recovery.

It’s OK to not be 100% well everyday. It’s OK to look after yourself.

If I can, I’ll take a bath and relax, listen to music… anything that helps me feel well cared for.

Related Post: Surviving Thyroid Flare Ups When You’re a Parent

But most importantly: take it easy.

Don’t over-do anything, as you’ll just make it worse, so instead listen to your body and do not in anyway overexert it during a flare up. Don’t do anything requiring too much from you mentally, physically or emotionally. Just rest and look after your body. After all, you only get one.

What are thyroid flare ups like for you?

You can click on the hyperlinks in the above post to learn more and see references to information given.

Please remember that if you’re a thyroid patient living with poor mental health or lingering physical symptoms, that you don’t have to live this way. To address why you may still be feeling unwell (often despite being on thyroid medication too), please see this article and go through each suggestion, putting your thyroid jigsaw back together.



Be Your Own Thyroid Advocate Book CoverSee also:

The book Be Your Own Thyroid Advocate: When You’re Sick and Tired of Being Sick and Tiredwhich builds on this article in detail.

Thyroid Superhero: A Kid’s Guide To Understanding Their Grown-up’s Hypothyroidism, which helps children to understand their caregiver’s thyroid medication, flare days, symptoms and more.

About Author

Rachel Hill is the highly ranked and multi-award winning thyroid patient advocate, writer, speaker and author behind The Invisible Hypothyroidism. Her thyroid advocacy work includes writing articles, authoring books, producing her Thyroid Family email newsletters and speaking on podcasts and at events about the many aspects thyroid disease affects and how to overcome these. She is well-recognised as a crucial and influential contributor to the thyroid community and has a large social media presence. Her bestselling books include "Be Your Own Thyroid Advocate" and "You, Me and Hypothyroidism".


  • Jana
    December 15, 2023 at 1:11 am

    I haven’t had a flare in YEARS! And here I am in the holiday spirit, eating gluten and sugar like it won’t affect me when BAM full blown flare up! Fatigue, dry itchy skin, brain fog, chills and even ringing ears. I gave up gluten over a decade ago but recently added it back in on occasion and it didn’t seem to bother me. But there is a threshold , which I learned the hard way. Back to no gluten and eating healthy! I’m hoping this doesn’t too long. Thanks for validating what I felt sure was going on.

  • Jeanie
    July 1, 2022 at 10:41 pm

    Does anyone get both hot & cold at the same exact time?!

  • Olga
    February 21, 2021 at 11:01 pm

    Would anyone know if there is possibility the perimenopause could trigger a flare that cannot seem to go away?
    I have had Hashimoto’s for many years now and have successfully controlled it through diet and natural supplementation, healthy sleep, and movement. Occasional flare up here and there over the years, but like you ladies say, it is not uncommon.
    Now, I am in an absolute hell and nothing, absolutely nothing is helping. It’s been three months since it began, it began with a period, but then that was irregular (wouldn’t end, then wouldn’t start…). I wasn’t sure if the hormones were affecting the autoimmune or the autoimmune cause the hormonal imbalance. But it seems that there’s nothing I can do that worked for me before, almost like a whole new thing.
    I am calling my doctor this week to get blood work done, but in the meantime incredibly stressed about this new turn of events, and searching for answers. I’m 45, the only thing I can think of is the beginning of menopause.

    • Tracey
      February 3, 2022 at 10:49 am

      I’m the same. Feel like I’m losing my mind. I was over medicated and the doc has dropped my meds but my mental health is suffering and he proscribed me anti depressants which I really don’t want to take.
      My hormones seem to fluctuate all day. I feel good one minute and horrible the next

  • Floor
    January 3, 2021 at 2:37 pm

    I am in the middle of one, that is how I found your website… After a week of sleeping 8 hours each night but still feeling tired, this morning I just felt absolutely exhausted, muscle pain and very cold. Just trying to get me through the day and accept it, which is hard since I had planned a nice Sunday with our newborn.

  • Carol Wade
    January 2, 2021 at 6:00 pm

    Can anyone explain why my TSH went from 1.46 to 27.32 in three months time? I had an episode of extreme pain over my entire body except for my hands and feet. This went on for days…I could not turn over in bed without help, could hardly walk, etc. Went and had blookwork… conclusion…audioimmune disorder.

  • Megan
    September 10, 2020 at 1:28 am

    It’s been a couple of years since I had a full on flare up. I’d forgotten how awful it is. My current one was triggered by the stress of a breakup shortly followed by losing my job, a wonderful couple of months 🙂 The thing is you end up in a cycle if you’re not careful which I am trying to escape now. The stress & anxiety from life’s events triggers a flare, then the symptoms of the flare make the anxiety worse due to the hormones being out of balance and then you revisit the life events which are now hormonally charged as well. It becomes very difficult to grab a hold of something to calm the system down. I find in these moments mediation doesn’t work as I can’t focus at all. Running, my usual way of dealing with stress is difficult because the body is tired & I have insomnia. I also find I have a f*%k it attitude to food & my diet which I am usually so on top of slips & I eat sugar & am not so on top of gluten which I never touch usually which I know makes the whole thing worse.

    To anyone going through a flare up & to those of you newly diagnosed who haven’t quite got it under control yet. Remember the good days! I have had a diagnosis of Hashimotos since 2013 & I have a very physically demanding lifestyle & job & sure it’s a pain in the butt sometimes but the majority of the time I am in a good place. It took a couple of years to find balance in diet & the right medication but the good days exist and are possible. Don’t let your healthcare provider tell you otherwise you know your body and you’ll know it a helluva lot more as you walk this journey & learn what foods your body (dis)likes & sleep etc which is pretty awesome really.

  • Lewis Housten
    March 5, 2020 at 11:35 am

    I absolutely hate this condition. Thanks for writing this post. I’ll save it for future reference.

  • Emily Milliman
    January 21, 2020 at 3:43 pm

    Reading this today as I experience what I think is a thyroid flare up day after over exerting myself physically and getting too stressed at work. It is so hard to cancel plans and push everything out of your life for a day, but sometimes I just have to do it. We are stronger for having this health challenge. I think the fact that it seems invisible and that I look “fine” most days is the hardest part!

  • Cheryl
    December 12, 2019 at 1:17 am

    Just happened to see this. It is so true about these flares.
    I was and had been a high functioning healthcare professional.
    Now, I pray and try to push through.
    I have Hashimoto’s, POTs, Dysautonomia, MCAS, and possibly Graves.
    I’m alone, I have no family support, friends have there own problems.
    Invisible illness. I fear what will happen to me if I can’t push through.
    Thank you for sharing this.

    • Emily
      January 21, 2020 at 3:45 pm

      Thx for sharing. Our society is really fast paced and sometimes our bodies have ways of telling us to slow down. It can be hard to listen, but knowing others are going they the same thing helps me a lot!

  • Susan Mckay
    May 26, 2019 at 7:47 pm

    I have this condition, and during the months before I was diagnosed I hurt many relationships with family and friends. I am still trying to piece back my family and life…it has been 8 years of finding a diagnosis and recovery physically…now the hardest part is the emotional recovery. People think I am making an excuse for my behavior….but until they have walked in the shoes of someone who suffers from this condition, they will never know the pain and agony we have gone through and struggle with every day.
    I hope anyone who has experienced this takes comfort in knowing YOU are a good person…you have had a bad health experience… don’t be so hard on yourself.

    • Rachel Hill
      May 28, 2019 at 12:35 pm

      An important message Susan. Thank you for sharing.

    • Cindy
      March 31, 2022 at 7:13 am

      Susan I know all to well how u feel . My family thinks I don’t want to be around them . My dad called me crying and ask me why didn’t I love him anymore. I have alot of health issues and it’s really hard for me to get out . I feel like when I am around then that they r judging me. I’m having a really bad flare up . Just wish they could understand. For I love love and need there support. I thought I was the only one who felt this way then I read what u wrote. Thanks for sharing.would love to text some time


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