Are You Living Life with Thyroid Brain Fog?

Are you living life with thyroid brain fog?

Could brain fog be a warning sign your thyroid is NOT optimally treated?

It’s critical you find out.

Poorly managed hypothyroidism can have a powerful effect on your brain.

Written by Hugh Melnick, MD, F.A.C.O.G.

At one time or another, everyone has suffered from what they would describe as brain fog. The following factors can bring with them a decreased sense of neurological function:

  • Stress
  • Pregnancy
  • Sleep deprivation
  • Illness

Let’s focus on the last item and find out more about how brain fog relates to hypothyroidism.

Critical Mood Deterioration

These three words are how medical experts and research analysts describe the mentally foggy state that many thyroid patients find themselves in. In fact, current studies indicate that an underactive thyroid can take a significant toll on your mental health.

There’s more to hypothyroidism than the physical symptoms we’ve all learned to watch for. The fact of the matter is that over time, a thyroid gland that produces less hormone than it should will affect your neurological function.

Why? Because the hormone deficiency slows everything down, including neurological functions.

This domino effect can leave you with a chemical imbalance that includes symptoms like:

  • Inability to concentrate
  • Detachment from personal relationships and activities
  • Low self-esteem
  • Depression
  • Inability to connect details
  • Short-term memory problems
  • Slowed mental reactions
  • Confusion

As your undiagnosed symptoms worsen, your quality of life also decreases.

Temporary Fog or Something Else?

Brain fog has many causes and thyroid problems are definitely on the list. Anything that causes a misfire in your neurotransmitters can lead to a feeling of forgetfulness or living in a mental fog. But it’s very important to realize when these symptoms might be indicating that you have a serious health problem.

Stress or even trouble sleeping can trigger temporary brain fog. We’ve all been in situations where feeling emotionally overwhelmed or tired leaves us also feeling mentally slower than usual.

The question we need to ask ourselves is: when might it be something more serious? Brain fog can actually signal the onset of disorders and processes in the body that need to be managed and addressed such as:

  • Thyroid Problems
  • Adrenal Failure
  • Menopause

Living Life in a Thyroid Brain Fog

Unfortunately, the neurological symptoms that about 5% of all hypothyroidism patients suffer from are largely underestimated or outright ignored by a lot of practicing medical professionals.

This is not something that can simply be treated with complimentary drug therapy. It takes more than antidepressants to really understand and address this problem – it takes looking at thyroid function as a whole.

Patients often complain that even though they are in treatment for their thyroid condition, they don’t feel better physically or mentally.

Many doctors write this off as a casualty of the adjustment process, but if they look closer, and pay attention a little sooner, these mental changes could be an effective early warning sign of an underlying thyroid condition.

Thyroid conditions are notoriously difficult to diagnose in the early stages. The standard blood tests aren’t accurate and it’s easy to confuse the symptom presentation with other health problems. Search until you find a  doctor who will listen.

The Thyroid

The thyroid gland is a small, butterfly shaped mass of tissue found in the neck, just below the “Adam’s Apple.” Despite its small size, it has a critical role in determining how our bodies function, and, ultimately, how well we feel.The thyroid controls the body’s metabolism, which is the energy supply that is essential for all bodily functions. Think of the thyroid gland as an automobile’s fuel pump. If the pump is not working up to capacity, the car’s engine will not get enough fuel, and will run slowly and inefficiently. Should the pump supply too much fuel to the engine, it will run too fast and eventually burn out. An underactive thyroid gland causes a medical condition known as hypothyroidism.

For some unknown reason, it occurs much more frequently in women than in men, and as many as 15% of the female population may have some degree of thyroid under activity.

Thyroid Symptoms

The symptoms of hypothyroidism are quite common and diverse. They affect the way a woman looks and feels, both physically and emotionally. Without any doubt, an untreated under active thyroid gland can have a profoundly negative effect upon a woman’s quality of life.

Having seen the wide spectrum of symptoms associated with hypothyroidism, it is apparent that they are extremely common complaints, experienced by many women. It is quite possible that either you, one of your friends or a family member is plagued by one or more of these troublesome symptoms. Many times, women with these complaints have been tested for hypothyroidism and were told that, despite their symptoms, they did not have an under active thyroid gland because their thyroid blood test results were within the “normal” range. They may have been told that their symptoms are part of the “normal” aging process or are caused by anxiety or depression. In many instances, they are referred to a psychiatrist for treatment with antidepressants and psychotherapy, but often these treatments may not make a symptomatic woman feel better.

A Common Thread of Progression

Rather than list all possible symptoms of hypothyroidism; I’ve chosen to list one of the most common symptomatic progressions. This is the typical presentation most patients go through:

  • Most symptoms, such as lower heart rate, tiredness, poor memory or difficulty in thinking, and even constipation, are due to inadequate stimulation of the various organs in the body due to insufficient amounts of thyroid hormone.
  • Other symptoms, such as inability to tolerate cold environments, are directly due to the decrease in heat generated within the body by slowed metabolic activity.

Most people with hypothyroidism will experience some of the following symptoms:

  • Slow heart rate
  • Tiredness
  • Inability to tolerate cold
  • Weight gain
  • Emotional depression
  • Drowsiness, even after sleeping through the night
  • Heavy or irregular menstrual periods (in premenopausal women)
  • Muscle cramps
  • Constipation

Later symptoms of hypothyroidism include:

  • Dry, flaky skin
  • Hair loss
  • Impaired memory and difficulty in thinking
  • A deepening voice
  • A numb sensation in the arms and legs
  • Puffiness in the face, especially around the eyes (a condition called myxedema, which is an indication that the disease has become serious)

Subclinical Hypothyroidism

Such symptomatic individuals may actually have a condition known as Subclinical Hypothyroidism. In this clinical condition, a patient may be symptomatically hypothyroid, yet her blood tests may suggest, but not fully support, the diagnosis of thyroid gland under activity. In subclinical hypothyroidism, there is a partial decrease in the thyroid glands ability to produce enough hormones to make the body’s metabolism work at 100% efficiency; hence an individual will be symptomatic. Such individuals may benefit from a therapeutic trial of treatment with a natural prescription thyroid supplement.

There are two basic problems that account for the failure to diagnose many cases of subclinical hypothyroidism. First is that what is considered to be the “normal range” for one of the main blood tests used to diagnose hypothyroidism (TSH-Thyroid Stimulating Hormone) is too broad to diagnose many patients who are symptomatically hypothyroid. In addition to TSH levels, the amount of other thyroid hormones such as T4 and T3, as well as antibodies against thyroid tissue, must be evaluated in any woman having symptoms associated with hypothyroidism.

The second difficulty in diagnosing hypothyroidism is that we, as physicians and scientists, are trained to rely more on objective findings, such as laboratory tests, than subjective factors, such as a patient’s symptoms. Unfortunately, many doctors will not feel comfortable making a diagnosis of hypothyroidism if a patient’s blood tests fall anywhere within what is strictly defined as the normal range, even if such levels may be close to indicating the possibility of an under-active thyroid gland in a symptomatic patient. There are definite “gray zones” that exist clinically; such that a patient’s clinical symptoms may not be completely documented by their laboratory results.

It is important to remember that blood tests only reflect a “moment in time” in the human body and consequently may not always accurately represent its true condition! Therefore, a patient’s symptoms must be considered as being of equal significance as their blood test results in diagnosing hypothyroidism.

In my experience, many women who present with physical and psychological symptoms associated with hypothyroidism will have some degree of improvement when treated with supplemental thyroid medication.

Improvement should be noted in two to eight weeks. Increases in energy levels, sex drive, body temperature and memory are the first changes noted. Water retention also improves fairly rapidly. An increased feeling of well-being may also be noticed, as depression resolves.

Hair and skin begin to improve after 4-6 weeks, but weight loss usually will take quite a bit longer since the body takes time to breakdown existing fatty deposits. When I treat women who have symptoms associated with hypothyroidism, I initially use a natural desiccated thyroid medication (NDT) that has been available since the 1940’s, such as the brand Armour Thyroid Extract U.S.P. It is a combination of two active forms of thyroid hormone, T3 and T4. T4 is the form of the thyroid hormone that is in the synthetic thyroid medications commonly prescribed today. Normally, T4 is converted into T3, which is the biologically active form of the thyroid hormone that actually controls the body’s metabolism. In a significant number of individuals, the body is unable to properly convert T4 into T3. Hence a patient may be clinically hypothyroid, yet have “normal” blood tests. Therefore, I find that a woman’s clinical response to the natural form of a combination of T3 and T4, will often be better than giving T4 alone.

It is of critical importance that a physician be finely attuned to a patient’s symptoms and her symptomatic response to treatment. Thyroid supplement therapy is very individualized, since the dosage requirements are quite different for each patient. A patient’s dosage needs to be reevaluated based upon the degree of symptomatic improvement and “finetuned” as necessary.

The important point to remember is that the evaluation of symptoms is of equal significance to the levels of thyroid hormone in the blood.


The diversity of symptoms can make the diagnosis and treatment of hypothyroidism quite challenging, especially since laboratory tests do not always reflect thyroid gland under activity in a significant number of symptomatic individuals.

If you, a friend, or a loved one experience any of the above symptoms or generally feel poorly, you should speak to your doctor about the possibility that subclinical hypothyroidism may be the cause of such symptoms. After an appropriate diagnostic evaluation of symptoms and laboratory tests, a therapeutic trial of a natural thyroid supplement or any other thyroid medication may provide relief from these troubling symptoms.

Thyroid conditions are notoriously difficult to diagnose and treat optimally. Search until you find a doctor that will listen.

About Hugh Melnick, MD, F.A.C.O.G.

Dr. Hugh D. Melnick is a reproductive endocrinologist who has been treating patients with hormonal and fertility problems since 1976. In 1983, Dr. Melnick founded Advanced Fertility Services, which was the first free standing In Vitro Fertilization Center in New York City and is still its medical director. Dr. Melnick’s vast clinical experience together with his own personal experience having hypothyroidism has enabled him to develop a unique approach to the diagnosis and treatment of hypothyroidism. During his many years of clinical practice, he has recognized how hypothyroidism can adversely affect every part of the human body, creating many unpleasant symptoms, which inevitably interfere with a productive and enjoyable quality of life. In addition to his fertility services, he works with thyroid patients at


Huong, T.D., et al. Desiccated thyroid extract compared with levothyroxine in the treatment of hypothyroidism: a randomized, double-blind, crossover study. J Clin Endocrinol Metab. 2013 May;98(5):1982-90.

READ NEXT: Why are there so many unhappy thyroid patients?

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About Dana Trentini

Dana Trentini founded Hypothyroid Mom October 2012 in memory of the unborn baby she lost to hypothyroidism. This is for informational purposes only and should not be considered a substitute for consulting your physician regarding medical advice pertaining to your health. Hypothyroid Mom includes affiliate links including the Amazon Services LLC Associates Program.


  1. randy black says

    does proper dosage of medication and proper T3, T4 levels due to said dosage, correct this issue?

  2. Elspeth Miller says

    i have had thyroid problems for 20 years and dealing with all these problems but when you cant get a Doctors appointment and only get a telephone consultation 3 weeks later after blood results what the hell are you supposed to do . Thyroid is not to be taken lightly it is there to make the body function so Doctors take this seriously we no when our body is not right .

  3. Jackie Clench says

    Hi can Underactivethyroid interfere with your digestion when I eat sometimes about an hour later I feel very hot and uncomfortable sometimes with a stomach ache then I worry which makes things worse

  4. Kimberly Scott says

    Hello, I was diagnosed with Narcolepsy 5 months ago. The meds they are prescribing are barely helping me make it through my work day. What happens to me without meds is what I describe as a trance or a severe brain fog. I do ultrasounds and I can feel this fog come on. I begin to get very sleepy and absolutely cannot think straight. I will remain awake, take ultrasound images on my machine, type nonsense on the screen, all while staring at the screen KNOWING in my brain I am not doing the test right but am UNABLE to make the corrections. Its like cognitively my brain decided to take a nap. It Will allow me to go “through the motions” but not make actual cognitive decisions. This trance lasts about 20 minutes. Then I am able to recover and think clear enough to fix the mistakes I’ve made. The Narcolepsy was diagnosed properly through sleep studies and MSLT however it was determined that some pain medication may have skewed the results. Through a more thorough medical history, a University neurologist believes the trances may be linked to severe depression and sleep deprivation. I too have been tested for hypothyroidism and tests came back positive 1 year, then I quit taking the meds and ever since then all tests have been on the normal range. Long story…sorry. Just wondering if a lower normal range throid level could be responsible for the poor sleep, depression and is manifesting in these trances that are killing me.

    • Hi, it has been my experience to suffer with being tired alot, even after a nights sleep, brain fog, and anxiety and depression. WHEN I forget to take my meds, it’s worse, usually on the weekends due to a change in my work routine. When that happens I will feel very tired for a few days till my thyroid readjust to what’s missing. I would suggest a full thyroid panel of blood work to understand just how the numbers are and NORMAL isn’t always optimal for you.

  5. In your experience do physicians only treat hypothyroid when TSH is over 10? That’s what they tell me (in northern Canada). My TSH has been 4ish for more than a decade. I have celiac disease, an autoimmune disorder. Thank you for the useful website!!

  6. My name is Maria? I had my thyroid removed completely in 1994, I have been on the same dosage of levothyroxin for almost 5 years now. But I feel very poorly. And doctors here do nothing, you have to actually be proactive and suggest tests and treatment..
    what kind of tests or treatment can I bring up on my next appointment?

    • Hi Maria! I had my thyroid removed August last year, and I’m going crazy with all the changes! Did you gain weight? Any advice?

  7. Tired beyond belief, snappy at home, sit in meeting and have no idea what they are talking about or why I’m there, lacking motivation, gaining weight, upset stomach, vomiting, lowered immunity and in 175mg of Levothyroxine…….don’t you just love Hypothyroidism!!!!

  8. Hi all,
    This form has been so helpful. I am experiencing mental impairments that my doctor velives is due to hypothyroidism. Depression feeling empty and worthless and hopeless which is the worst. And brain fog inability to concentrate and collect and store facts in my short term memory. No remembering people and my connections with them like really trival individuals. I feel slow like I can’t think and form when presented with new information and things . It’s hard. I feel like I’m declining. And weight gain. I will say that when I took the levaithan tablets (check spelling) at night because they weren’t absorbing in the morning I did feel a bit better. But I need my memory and rationalizing facilities it’s hard to feel clogged in identity in your own body and not be able to grow with people in conversations and in reality feeling disjointed. It’s hard piecing this life together again so your stories have been extremely hopeful.

  9. Hi Jeanette,
    Sorry to hear how you were feeling. I believe I’m experiencing the same thing.
    I have had Cushings which resulted in secondary hypothyroidism. Lately, my brain fog has gotten so bad that at times I loose track of my thoughts,cant find the right words and forget things just told to me. It is not only frustrating but scarey. Im 47 and also believe I may becoming menopausal. I had radiation to the Pituitary in 2016,which takes about 18 months to take affect. Well, I believe it has.
    I have also heard it’s reversable, so Im hoping my endo will quickly address as my primary did recent labs TSH .71, Free t 3 low, T4 low. How long have you been on the Armour?

  10. Jeanette M Hurst says

    I was untreated with Hypothyroidism for over 5 years, it got to the point where my body temperature would drop to 95.1, I could barely move and I made garbly sounds instead of words when I tried to speak, I could not even remember my own son’s name, but so much more than that. I truly thought I was dying. I finally after going into my doctors office and getting on my knees and crying to her she decided to start me on Levothyroxine and then when that did not take it all away, I would not leave the office until I got Armour. I am feeling so much better, I can’t even tell you what a wonderful change it has made. But I am still finding that I am using the wrong words, or find it hard to recognize people I should know, I can not find any research on the effects on the brain after long term untreated hypothyroidism, basically Myxedema, borderline coma. Can anyone point me to any research, all I find is that with treatment it is reversible. What kind of research have they done to show how many of those who were left untreated get diagnosed with Dementia later in life or never get their full brain function back, like me. Please any help would be wonderful

  11. Jeanette M Hurst says

    I was untreated with Hypothyroidism for over 5 years, it got to the point where my body temperature would drop to 95.1, I could barrely move and I made garbly sounds instead of words when I tried to speak, I could not even remember my own son’s name, but so much more than that. I truly thought I was dying. I finally after going into my doctors office and getting on my knees and crying to her she decided to start me on Levothyroxine and then when that did not take it all away, I would not leave the office until I got Armour. I am feeling so much better, I can’t even tell you what a wonderful change it has made. But I am still finding that I am using the wrong words, or find it hard to recognize people I should know, I can not find any research on the effects on the brain after long term untreated hypothyroidism, basically Myxedema, borderline coma. Can anyone point me to any research, all I find is that with treatment it is reversible. What kind of research have they done to show how many of those who were left untreated get diagnosed with Dementia later in life or never get their full brain function back, like me. Please any help would be wonderful

  12. Tracy Smith says

    Please speak more about overdosing on medication. I just found out I have been taking to much medication for over twelve years. I just got a new Dr who has me on a lower dose that I’ve never been on. I’m feeling so much better over all. I’ve been trying to tell me last Dr that I’ve been feeling off and was always told my level are fine. No one is talking about this please do.

  13. Sam Sarwar says

    I stumbled upon this marvelous post while searching for a miracle cure for so many symptoms I have been suffering throughout my 30 years of life.

    I am subclinical hypothyroid but my symptoms feel like shooting through the roof, which no doctor ever believes and never prescribe any medication. its always been, you are low in iron, you are overweight. I am so sick of it all.

    I am in London, England. I am really interested in that NDT medication. Would you happen to know what its called here in UK so I can ask my very stubborn GP about it?

    Thank you for the post. I felt like there is someone who thinks I am not lying.


  14. I wish you would have been around 25 years ago…….Oh my did I suffer through numerous doctors, health plans and treatments. I would tell doctors I was truly sick, in pain, unable to function. Yet at the end it was always the same response…… There’s nothing wrong with you, here take this it will make you feel better! Yes, I like many other women and men are prescribed feel good medications (for depression) and mood alteration…….There’s nothing wrong with you “Bullshit” I would say, or maybe something a bit stronger….. I’m truly sick help me please, don’t alter my mood……I never made the mistake of taking the constantly prescribe antidepressant. I had a closet full of unused antidepressant samples I could have been a supplier….. I was finally diagnosed 10 years ago. However, by that time I was diagnosed my TSH level was 78.0 Yes, crazy off the chart number……I could barely walk, talk, or think, I cried at the drop of a hat, I was fainting constantly. They finally prescribed Levothroid, and for years and years I told them many of my symptoms still persisted, I finally found a doctor that agreed to treat me with Armor Thyroid. Kaiser doesn’t wont to prescribe it they charge a lot more for the special order prescription and say its a liability to use? I’m now 57 and going through Menopause, and finding it hard to keep the brain fog away, short term memory loss, tingling in face, hands,and lips,……I have Kaiser Ins. here in California, which uses a western medical approach, they ignorantly still use the TSH table of .04 – 4.5…..After 2.5 I’m feeling pretty bad……But they don’t recognize it! Don’t check my T3 & T4 levels, I’ve been taking 90mg for over three years….Any advice is welcome….

    • Hi there,
      My name is also Rachael! I like your spelling…😉 I just came across your post as I was reading this from my doctor. I’m not sure where it is that you are located but she offers some excellent advice as I too am having major thyroid issues and we have a lot of symptoms in common. I was thinking if you’d like, maybe you could get in touch with her. And even if your not down here in Southern Florida, Coconut Creek is where she is located, maybe you’ll be able to get in touch with her and she might be able to help refer you to the right person and what questions you might need to ask, or even of you would just like to follow her info on FB. I hope this helps and I’m catching you on a good day. Feel better…
      Her info is:
      Dr. Tara Solomon

    • Ahhh, just saw you’re in Cali.. Hope this can still be helpful… 🙂

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