13 Signs of An Underactive Thyroid: Do You Know What To Look For?


[Last updated 26th October, 2018]

Also known as an underactive thyroid, hypothyroidism is caused by a defect in the thyroid gland that leads to low thyroid hormone levels.

Estimates suggest it affects up to 8.5% of people from Western countries, and around 20 million Americans (1).

What’s more worrying, however, is that up to 60% of people are undiagnosed, often because we don’t realise what the symptoms of an underactive thyroid are.

This is a researched list of the major signs and symptoms to look out for. If you have three or more symptoms, you should check your thyroid hormone levels at the doctor.

1. Excessive fatigue is the most common underactive thyroid symptom

Excessive fatigue is the most common underactive thyroid symptomThis symptom may seem very vague and general, but it’s not.

In the renowned DanThyr (Danish Thyroid) study from Denmark, 4 out of 5 men and women with hypothyroidism reported experiencing chronic fatigue. This is actually the number 1 most commonly reported symptom (2).

Excessive fatigue and weakness can be described as extreme lethargy, where you are feeling too weak to do your regular everyday activities. It’s also a common early sign of type 2 diabetes.

2. Weight gain or much greater difficulty losing weight

Weight gain or much greater difficulty losing weight with hypothyroidismAs the thyroid hormone regulates metabolism, an underactive thyroid often leads to a low metabolic rate.

The result is a tendency for body weight to increase during development of severe hypothyroidism. Likewise, this makes losing weight much more difficult.

In fact, a Danish study of newly diagnosed hypothyroidism patients found that patients weighed on average 7 kg (15.4 lbs) more than the control group (those with no thyroid disorder) (3).

But it turns out this weight gain is due in part to severe water retention caused by low thyroid hormone (4). Alongside a slower metabolism and low energy levels, these symptoms accumulate to drive thyroid-related weight gain.

3. You recently quit smoking

Ex-smokers have a greater risk of hypothyroidismWeight gain is very common after an individual quits smoking.

A 10-year study found it causes an average of 4-5 kg gain (9-11 lbs), which is largely due to hormonal changes that occur after cessation (5).

One of the main hormonal changes is related to the thyroid. In fact, you have a 6-to 7-fold increase in the risk of developing hypothyroidism after quitting smoking (3).

For this reason anyone experiencing unwanted weight gain after quitting smoking should have thyroid function tested.

4. Memory loss and “Brain Fog” is a sign of hypothyroidism

Memory loss and “Brain Fog” can indicate a thyroid problemThe brain is a major target organ for thyroid hormones. This is why the onset of hypothyroidism (as an adult) can affect brain function.

Clinical trials and functional imaging studies of the brain confirm that advanced hypothyroidism is associated with cognitive decline- largely reversible with treatment (6).

In contrast, subclinical (early-stage) hypothyroidism is not linked with major neuropsychiatric problems, although studies show small (reversible) deficits in memory and executive function do occur. This is most often described by patients as experiencing “brain fog”.

5. Excessively dry skin

Does your skin frequently get dry and itchy? To the point where it’s very visible?

Excessively dry skin is actually the second most common sign of hypothyroidism (62% of patients) according to the DanThyr study (3).

Note that this symptom can overlap with early signs of insulin resistance.

6. High LDL cholesterol levels could be a warning sign

High LDL cholesterol levels could be a warning sign of hypothyroidAn increase in LDL particle number (or Apo-B levels) is a known risk factor for heart disease.

Thyroid hormones are known to affect the heart and blood vessels, and the weight of evidence suggests hypothyroidism (even in its early-stage) is associated with modest increases in LDL “bad” cholesterol, Apo-B levels and triglycerides (7, 8).

There are several proposed mechanisms behind this link, but just how influential hypothyroidism is on heart disease risk in the long-run is not well understood and potentially exaggerated (9). There are so many other lifestyle factors that influence these heart health markers.

For this reason I don’t consider high LDL on its own as a strong indicator of hypothyroidism.

7. Frequent muscle aches and tenderness

A common complaint of those with undiagnosed thyroid issues is frequent muscle aches.

It can be characterised by long-term and widespread pain and soreness. This pain is often not specific to one particular area- much like those diagnosed with fibromyalgia.

In fact, both an underactive thyroid and fibromyalgia can be linked to a food intolerance (quite likely FODMAPs).

8. Irregular menstrual periods could be an underactive thyroid symptom

Irregular menstrual periods could be a sign of hypothyroidismDid you know women are thought to be 5 to 8 times more likely than men to have thyroid problems?

One well-known symptom is large changes to menstrual cycle length and blood flow, even Amenorrhoea.

Studies have found that 8-12% of women with healthy thyroid function experience irregular periods, compared to 23-68% of women with hypothyroidism (10).

9. Increased sensitivity to the cold

An underactive thyroid can can disrupt the body’s innate ability to regulate body temperature.

This may cause you to feel somewhat colder than usual, particularly in situations where others around you are not feeling it.

10. Neck discomfort or swelling

Neck discomfort or swelling is a sign of underactive thyroidJust over 50% of patients in the DanThyr study reported that neck discomfort was a sign of hypothyroidism (3).

The discomfort can be caused by inflammation of the thyroid gland’s cells, known as thyroiditis. The gland can actually become smaller or larger (known as goitre), depending on the cause of the disorder.

Hashimoto’s thyroiditis is actually the most common cause of hypothyroidism, and is most typically described by patients as a sensation of “something in the throat.”

11. Constipation is a sign and symptom of hypothyroidism

Constipation is a sign and symptom of hypothyroidismConstipation is a commonly reported sign, one that usually resolves after correcting a thyroid hormone imbalance.

The mechanism behind this link is unclear, though many propose it is because of the gut-thyroid connection.

Much like high cholesterol that was listed above, note that chronic constipation on its own is very unlikely to indicate hypothyroidism (11).

12. Feeling low or depressed

Feeling low or depressedMental health problems such as depression, chronic stress and anxiety tend to go hand-in-hand with hypothyroidism.

Whether this is a direct effect of hormonal imbalance is debatable though, as these symptoms are not experienced by all patients (12).

It seems more likely the result of numerous unmanaged hypothyroid symptoms that have accumulated over time to make life miserable.

13. Thinning hair

Hair loss is one of the most feared underactive thyroid symptom in women.

It occurs when the thyroid hormones are unbalanced, and can actually happen during both hypothyroidism (underactive) and hyperthyroidism (overactive).

In a study of 100 women experiencing hair loss, researchers estimated that hypothyroidism was responsible for 10% of participants (13).

Fortunately in the majority of cases hair grows back once the thyroid imbalance is treated.

Do you experience these underactive thyroid symptoms and signs?

If you have an underactive thyroid you may experience any number of these warning signs.

Generally speaking, problems tend to develop slowly over a number of years. It really depends on the severity of thyroid hormone deficiency and the length of time you’ve had it.

You should see your doctor to your TSH levels if you’re experiencing three or more of these signs, and be sure to get a copy of the results.

Wish you could go back to how you felt before thyroid symptoms?

Now you can.

Introducing my Thyroid “Time Machine” meal plan. Click here to learn more.

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13 Signs of Hypothyroidism Overlooked By Over 20 Million Women. Up to 60% of people with an underactive thyroid remain undiagnosed. Do you realise what the warning signs of hypothyroidism are?

About Joe Leech, Dietitian (MSc Nutrition & Dietetics)

Joe Leech is a university-qualified dietitian from Australia.

He graduated with a Bachelor's degree in exercise science, followed by a Master's degree in Nutrition and Dietetics in 2011.

Learn more about him on the About page

24 responses to “13 Signs of An Underactive Thyroid: Do You Know What To Look For?”

  1. I’m on underactive thyroid medications and have been for more than 15 years. My tests show I’m within the correct “range” but I still feel no improvement. I’m at the high side. Would I see any improvement if my medications were increased? I’m 68 yrs old and also have fibromyalgia. I have never had an adjustment in medications. Feel that many things are chocked up FM. It is even difficult for me to know the difference. What are the optimal ranges? Thanks for your help

    • Hi Shirley did you discuss with your doctor?

      This is common complaint for those who have been on the medication 10 years or more, as generally it becomes less effective over time. But this would show in blood work, whereas yours is not showing any issues.

      By no improvement, what symptoms do you refer to?

  2. Hi Joe,
    I felt compelled to message you, Thank You so much for the multitude of useful help advice and support you are giving here. Wow shopping lists and real can do recipes.
    One of the most useful sites I have managed to find…& (There have been Many).

    Like the lady above I too have been on Thyroxine for ten years without any changes to the dosage. I was a healthy weight of 9st.7. However I am now seriously struggling, big time…I am at the end of my tether with the rapid weight gain. Gaining almost 2 stone very quickly. I simply cannot shift an ounce in spite of my diet N exercise regimes. Many of my thyroid symptoms have increased. I was convinced I may need a little more Thyroxine. I was tested last week and the Dr says my reading normal, range is TSH 2. last year it was 2.4. I am so confused.
    My Dr states it is because I am Peri-menopausal and will only offer HRT & Antidepressants. I am not one for taking medicines and although over the past two years I have given into the Dr’s reasoning’s for using them , i did try them, I felt no benefit whatsoever and stopped them. I am not clinically depressed. I am frustrated that I am doing all I should to lose weight with no progress at all. I am now in the process of trying to get a referral to see a specialist.

    I have been eating nothing but protein and very small amounts of complex carbohydrates for weeks to no avail., feeling deprived & miserable ;-( .
    I was amazed to read about broccoli sprouts and cauliflower as I do eat these often so now I will be following your diet sheet.

    Thanks again for your valuable insight.

    • Hi Michelle,

      Thanks for your feedback 🙂
      I won’t pretend I know the solution to your situation, but it’s not uncommon.

      After 10 years or so on levo people report these symptoms consistently. Whether it is the extended use of meds, the hormonal shift with menopause, or both, is almost impossible to say.

      The only thing I have heard works for some (not all), is swapping levothyroxine for desiccated thyroid. It is a “natural” alternative that is worth discussing with your doctor. Still needs to be prescribed.

      Let me know how you get on. Alternatively you can email 🙂

      • Thanks for your reply Joe,
        Finally found a Dr that has not only really listened, he heard me. Dr has put my Thyroxine up for a few weeks to see how I go. Armed with your food lists and advice, fingers crossed it will all kick my system back into working better.

        I will keep you posted on my progress…(positive thinking me 😉

    • Hi Michelle

      I want to shout from the roof tops to everyone with this condition to change your diet. Cut out flour, so no bread, pies, cakes, biscuits, pasta, etc,etc. Eat more protein ie; meat, eggs, non-oily fish, shellfish, bone broth, fruit, root vegetables, coffee & fresh orange juice. Cook only in coconut oil & butter, no oils, no nuts, no grains. NO PROCESSED FOODS. I’ve done it and I feel fabulous. No more fatigue, weight back to normal. Good luck.

  3. I had my thyroid treated with Radioactive Iodine Treatment when i was 18 and was on treatment for underactive for years. Then i was tested many years later and said that i was overactive then overtime taken off medication but this last year i have been at odds my TSH levels are 3.8 and my T4 levels are 2.42 and they said that im in the normal range ..but i have all they symptoms of hypothyroidism. What should i do if anyone can help

  4. I am a 49yo registered nurse. For the past 8 yrs I have had all the major symptoms of an under active thyroid. Horrible fatigue, muscle aches and pains, brain fog, dry skin and hair, cold intolerance, weight gain, elevated LDL levels, etc. I even have unexplained shortness of breath and heart palpitations. I have been to a cardiologist and he tells my heart is fine. I have also been told I have fibromyalgia. I continue to gain weight and unable to lose any despite proper diet and exercise. My dr tells me I just need to eat less and exercise more and “are you depressed?” I have even been to an endocrinologist but my labs are always normal so they will not treat me for the condition. I have tried many supplements and remedies over the years to help heal the thyroid but nothing works. I am at my wits end and tired of feeling 89 instead of 49.

    • Try taking sea kelp which is a herbal tablet from Holland Barratt 3 x a day it has helped with my tiredness not the total answer and wont cure all evils that come with under active thyroid. I’m going through same and already have depression from my job so this another depression on top drives you mad with it all. I have even had the foggy brain when I make the most stupid of mistakes at work and its as if the brain just does not see things clearly until afterwards then you just get upset and feel stupid. Your not alone

      • Hi…i have hypothyroidism for last 10 yrs and I was loosing myself despite staying active. I am just 37 and doctors said my body is behaving like 60. I was also asked to try HRT. However i decided to go the ayurvedic way along with my presribed supplements. I feel much better mentally and keep myself active. I take 2 tsp of wheatgrass powder with 2tsp of Amla and aloe Vera juice in the morning with overnight soaked coriander seeds (tsp)water. Try doing this for a month and you will feel a difference. Flax seeds and chia seeds also help me a lot .All the Best and stay healthy.

  5. Please help me I have a under active thyroid I have all the things related to this condition the medication I am taking makes no difference I am so depressed I am a fighter but this thyroid has really got to me !! Sorry so hard to explain !!
    Will I really have to take this pills for the rest of my life ??

    • I have an underactive and came off Leveothyroxine( took 25 and increased to 50)after getting all the usual symptoms mainly weight gain. My gp has done a further blood test and one of my TS was 19 he says its border line and now referring me to a endocrinologist but unfortunately it can take up to 6 weeks. The reason for stopping it was mainly down to weight gain and aching in joints and not being able to get up for work so easily. I’m 51 years old and usually quite active and really having to push myself so I stick to swimming once a week riding bike to work on 2 days and 2 workouts at home. I have also taken sea kelp 3 x a day which has definately helped with the tiredness I do still get tired but only slightly. I also am going the the menopause and I know that this can also trigger an underactive thyroid and I am B12 deficient so on 3 monthly injections. Considering I’m going solo I consider myself as not bad still being able to exercise although it hasnt helped my weight it has stuck at 10:8.8 for 3 weeks now and to get to this it only came down by just under 2Ibs. The one thing I know that this is mostly doen to the under active thyroid and menopause hoping the endo once I get seen will prescribe something alternative to levothyroxine will never take tht again. will come back and update when I see them

  6. Hi all. i was diagnosed with an under active, 2 years ago by accident by having a health check at work. I asked my GP for a blood test, which was done and i have been taking thyroxine ever since, but have not really been told anything by my Gp other than i get free meds? and that my bloods are within range. i have read the above and have been able to relate to muscle pain for no reason, sore painful joints, elbows & knees. I suffer with headaches and migraines, but have not been asked about these since i have been diagnosed (should i have been asked about these?). I was a swimming teacher for over 20 years and have suffered mental health issues for almost 20 years being on different kinds of meds over the years, ( currently taking none) I am 52 years of age so i am going through the change……. Are these or could all of these things be related? I had a gastric band 6 years ago, but i am the same weight now as i was before i had it done. I paid over 6 thousand pounds to have it done and no blood tests were checked before the surgery. I am now struggling to eat any foods, sometimes i am unable to drink fluids. I have been to see a consultant at the hospital in the last 2 weeks about this and they have said they will check the band; which is now empty. Nobody has connected all of the above. They have said they will check for slippage, gaulestones etc. I would be very pleased if you could tell me if these things could be connected, as i have a planned appointment with my Gp on 12th November to ask to see a endocrinologist, who i have been told i should have seen at least once at the beginning. I would like someone to tell me what questions i need to ask, as i am suffering Brain fog and it is hard as i work 40 hours a week and quite a stress full job. Please help as i am clueless. Sorry about the spelling x

  7. I was just told I have low thyroid or Hypothyroid; I just started HRT, so before I was told of my results of the thyroid test, I am feeling way better after using HRT for the past 2 1/2 weeks. What I am reading here from some women at that stage of life of reaching menopause or peri, it might be something to look into. As for me a combination of both is what it seams to be. Oh, and I only do bio-identical that considers all hormones and not just estrogen.

  8. Thank you so much for this valuable information.

    It is people like you that really make a difference in the lives of people with hypothyroidism.

    I suffered for 12 years from hypothyroidism and nothing I tried worked.

    Drugs, nutrition, all types of doctors…you name it–the suffering never really went away.

    Fortunately, I found out about a natural way that finally got rid of my hypothyroidism for good.

    This article talks about it…


    Hope it helps and keep up the good work!

  9. Hi ive had underactive thyroids for over 10 years on thyroxin daily.I am over it as i can’t lose weight,I also suffer from high blood pressure cholestral.I do walking stand on my feet a lot at work,so i also have gout spur,paravisitus in my heels very painfull, diverticulitis as well ,gord, so i do watch what im eating ,i am a non smoker drink very little alcoholi am over weight but not obese, as i did ask doctor for the sleve,I also have rheumatoid and osteoarthritis what is the best advice for diet and fluid

  10. I was just diagnosed with Subclinical Hypothyroidism, and my doctor won’t treat with medications yet, despite me feeling awful and miserable every day and having 100% of the symptoms on this list.. should I seek out a different doctor? My symptoms are not improving and my doctor wants to “wait to see if it improves on it’s own or if it gets worse” but did not give me any advice on what to do in the mean time.

  11. I have low thyroid And wasn’t working and I’ve been taking medicine for it a long time and the last few months I’ve really been feeling so bad. My head feels funny and I feel bad all over. I just lay around almost all the time and I don’t feel like going anywhere because I feel so bad. I also get the feeling like I have something in my throat and it’s a uncomfortable feeling. All I want is to feel good again.

  12. I need to input, like a bunch at the same time as I hadn’t the benefit of examining everything you had to declare, I couldnt rally round on the contrary elude draw your attention before long. The as if you needed an excellent grasp on the subject ddbekedcdbbd

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