When symptoms continue on thyroid medication

When you are taking your thyroid medicine every day just like you’ve been prescribed and you still feel sick, sick, SICK.

Written by Paul Robinson

Once a doctor has prescribed thyroid medication to you, how is it possible that you continue to suffer more or less the same symptoms? Well, unfortunately, there are many really good reasons for this. Being aware of them can save you years of continued ill health.

You may go back time and time again to your doctor to discuss the on-going symptoms with him/her. You might even eventually change doctor. All of this takes a lot of time. Many weeks may pass by. The weeks may then turn into many months. Before you know it, several years have gone past, and you might still be struggling to feel well, even though you know that you shouldn’t be because you have been working on all the right things. 

Sometimes, completely relying on your doctor to fix your health is not going to work! 

Every patient needs to know enough to be able to work hand-in-hand with his or her doctor. Thyroid patients should be knowledgeable enough to assess if their current doctor is going to be able to help them or not. They need to be able to recognize when it is time to go and find a doctor who can work with them cooperatively. I will come back to this at the end of the article.

Let’s look at some common reasons that may cause you to continue to have symptoms of hypothyroidism while on thyroid medication.

1. Your thyroid medication dosage is never allowed to get to a high enough level because of the way your doctor is interpreting and applying your thyroid laboratory test results.

This point applies to all types of thyroid medication: T4, natural desiccated thyroid and T3.

a) TSH.

It is common for a doctor including endocrinologists to be focused on thyroid laboratory tests as the main way to manage your treatment. Many doctors are fixated on keeping TSH at a level they are happy with. This level might vary dramatically by country and by doctor. Some doctors prefer to see their patients on thyroid treatment having a TSH level lower than 2.0 but higher than 0.5. Some doctors might be happy with TSH below 5.0 but above 1.0. It is very common for many doctors to only use TSH to assess treatment success and to pronounce that everything is ok (regardless of FT4 or FT3 results). Invariably, most doctors and endocrinologists get uncomfortable if TSH gets very low and may reduce your thyroid medication if this happens. 

Many physicians think that simply getting TSH into the laboratory range means that your thyroid medication is at the correct level. This approach is wrong. TSH is a pituitary hormone and a poor measure of whether your treatment is adequate (although high TSH is likely to mean that the treatment is inadequate). Some people need more thyroid hormone and that might send TSH near zero – this may be perfectly acceptable, as long as the person is not showing indications of being hyperthyroid and their FT3 is not over the top of the reference range. However, in many cases, if TSH gets below 1.0, an endocrinologist or doctor is likely to reduce your thyroid medication, even if this makes your symptoms get worse.

b) TSH, FT4, FT3 & rT3.

More informed physicians use a wider range of thyroid laboratory test results than just TSH. However, even when these are all tested, it is no guarantee of being correctly treated. Often the thyroid laboratory test results are viewed as the ultimate window of truth on what is happening in your body. In fact, they are not that at all. They are often misused and misinterpreted by doctors who are not up to date with much of the new research and who are still sticking rigidly to outdated guidelines.

FT3 (Free T3) tracks symptom improvement. FT3 is the only thyroid lab that goes higher, as the person’s treatment begins to resolve symptoms. There is no relationship between TSH and FT4 and symptom improvement at all. So, a doctor who sees TSH and FT4 looking good may mistakenly think the treatment is successful, even if FT3 has not improved.

Also, many doctors do not pay attention to Reverse T3 (rT3). In some countries, the UK for one, rT3 is not even tested as most doctors think it is an inactive metabolite. Elevated rT3 is a marker of slower metabolism. Elevated rT3 does indeed reduce the number of D2 deiodinase enzymes that are present. Because it is D3 deiodinases that convert T4 to rT3, very high rT3 is a likely marker that these D3 enzymes may be interfering with T3 action in the cells (even though it is not rT3 that does this directly). So, high reverse T3 is a marker of T3 being blocked in both ways – through lower conversion (less D2 deiodinases) and blocked T3 (high D3 deiodinases).

Laboratory ranges are population ranges based on an amalgamation of data from many patients. These laboratory ranges are wide and do not reflect your own personal, necessary ranges. Unique, individual person ranges are less than half as wide as the laboratory ranges. In fact, an individual’s range for FT3 or FT4 is typically about 38% of the large population ranges that are our lab test result ranges. That’s a significant difference.

For example, imagine Janet had her FT3 tested and her result was 4.5 pmol/L with her laboratory reference range for FT3 being 3.3 – 6.6 pmol/L, Janet’s own personal range for good health might actually be 5.1 – 6.3 pmol/L and she would have to be within this personal range of FT3 to feel well. But, of course, Janet doesn’t know what her individual personal range is. Janet still feels pretty ill but her doctor is really happy with the 4.5 FT3 result and tells Janet she is correctly treated and he can’t make any changes to raise FT3 further.

The bottom line is that sometimes even a mid-range FT3 result is not enough for an individual.

Laboratory test results on their own often do not show what is happening in the patient’s body. The only things that actually indicate how thyroid hormone is working within your body are: Your Symptoms (and whether they are disappearing) and Your Signs (measures like body temperature, heart rate, blood pressure). 

The best way to go about monitoring a treatment’s success is to focus on the symptoms and signs of the patient i.e. the clinical presentation (in medical terminology). The thyroid laboratory test results should be looked at, of course, but do not be fooled into thinking that they show that you are properly treated. On their own, they do not. This is a biggie! It may be one of the single biggest reasons that thyroid patients do not recover.

2. Your doctor increased your thyroid medication. However, you developed symptoms of anxiety or high heart rate or palpitations when the increase happened. So, your doctor reduced your medication again.

Very often when this happens, it is not that the thyroid medication was too high. It was really that something else needs fixing. 

a) Low cortisol. 

If you have low cortisol and your thyroid medication is increased it is very likely that you will have some unpleasant symptoms. You might get a rapid heart rate, or a thumping beat in your heart. You might feel extremely anxious and edgy, or even irritable. Your body temperature might not rise as expected. You may be extremely fatigued. Dizziness due to low blood pressure can also happen. Sleeping might be very difficult. You may also feel nauseous or have digestive system upsets possibly including diarrhea. The symptoms are different in different people. But they are usually not pleasant and it is common for a doctor to just think your thyroid hormone is at fault.

Cortisol and thyroid hormone work together. The proper level of FT3 for an individual causes cortisol to work properly. The proper level of cortisol for a patient causes FT3 to work properly. Cortisol and thyroid hormone are synergistic.

It is next to impossible to guess if you have high or low cortisol – the symptoms can be very similar. Testing cortisol is essential. I always prefer to test both salivary cortisol (four samples over the day, including Dhea Sulfate), and an 8:00 am morning blood cortisol. This is because various things can corrupt a saliva cortisol result.

It is also worth being aware that fixing low cortisol does not always require hydrocortisone or adrenal cortex. Instead, just getting on the correct thyroid treatment for you can resolve the low cortisol issue. Sometimes other approaches are also required.

b) Low vitamin B12 (important for T4 to T3 conversion and can cause many severe symptoms overlapping with hypothyroidism).

If low B12 is present your thyroid medication may appear not to be working well. However, it may be the low B12 that is at fault. Debilitating fatigue is one of the major symptoms of low B12. Here is a link to more information on B12, including a longer list of symptoms.

If you have been taking any supplement containing B12 recently, testing it will not yield an accurate result. It is best to be off B12 for several weeks (months to be sure). The laboratory ranges for B12 are very wide and not helpful in deciding if B12 is low. The link I provided above about B12 will explain this and let you know what to look for in your results in terms of a ‘functional range’ for B12.

c) Low folate.

Folate is necessary for many purposes and it is very important in the methylation system. However, folate also works hand in hand with B12. Your B12 can be ideal, but if folate is low you can have all the symptoms of low B12. So, testing folate is also important. 

d) Low iron or ferritin.

Low iron and ferritin are well known to cause thyroid treatment to fail. It can be extremely difficult to raise the dosage of thyroid medication in the presence of either low iron or low ferritin. The symptoms of low iron or low ferritin are numerous and overlap a lot with those of hypothyroidism. It is very easy to assume that your thyroid medication is not working but really it is a low iron or a low ferritin issue. Fatigue, and general feelings of being unwell are common. Brain fog, anxiety and racing heart are also often present. 

So, testing serum iron, ferritin and TIBC (to be able to assess how much scope there is to take iron supplements) is important. You have to be off iron supplements for a week before testing iron and TIBC. For ferritin you can continue supplementing. 

e) Low vitamin D.

There are links between low vitamin D and hypothyroidism. Some of the symptoms of low vitamin D also overlap with low thyroid symptoms. So, again it is important to test this early on in order to not get confused during your treatment with thyroid hormones. 

3. You are actually on the wrong type of thyroid medication for you.

This is a worldwide problem and it happens so often. The majority of doctors are trained to think that T4/Synthroid/Levothyroxine is the only treatment that is ever needed. They think that T4 always converts to enough T3 and that this conversion cannot get compromised. This is a massively flawed assumption. Let me provide a few examples of why this is simply not true.

If someone has had a thyroidectomy or RAI or has had Hashimoto’s thyroiditis for many years, they will have lost some or all of their thyroid gland. The thyroid gland is the most important organ for the conversion of T4 to T3 in the body.

T4 has to be converted to enough T3, because T3 is the biologically active thyroid hormone. It is T3 that keeps us from being hypothyroid. T3 gives us energy and keeps our metabolism running well so that we don’t put on excessive weight. The loss of the thyroid gland will destroy nearly 25% of the capability to convert from T4 to T3. There is simply no getting this conversion back again once you have lost thyroid tissue. Unfortunately, doctors still continue to prescribe T4 on its own to those people who have lost this conversion capability along with their thyroid gland. Inevitably, this leaves them deficient in T3 and they often have remaining symptoms of hypothyroidism.

Anything that interferes with the ability to convert T4 to T3, OR that results in high Reverse T3 (rT3) is also a problem for those people who are only offered T4 medication. Reverse T3 is a T3 blocker and stops T3 from working properly – it is a brake on metabolism.

There are several other thyroid medication options.

a) A natural desiccated thyroid (NDT) product.

This contains T4 and some of the active T3. Because it contains T3 and T3 is quick acting and potent, NDT often has to be taken 2-3 times per day to spread out the T3 content. The ratio of T4 to T3 in NDT is fixed and is often around 4 to 1. The benefit of NDT is that it provides both T3 and T4 hormones. This helps those who have conversion issues and who have lost some or all thyroid tissue. The downside is that the ratio of T4 to T3 is fixed and whilst this fixed ratio may work well for many patients, it does not work well for all.

b) T4/T3 medication.

The T4 is usually taken once a day and then 2-3 doses of T3 are also taken during the day – much like NDT. The ratio of T4:T3 can of course now be varied and this can enable the person to have less T4 and more T3 if needed. This can be very helpful if the ratio of T4 to T3 within NDT is not quite right for you.

c) T3-Only medication.

If the problems are severe enough, this treatment can work really well, as no T4 is needed at all. This approach would eradicate all rT3 from the system over a few months. T3-Only can work perfectly well. I personally, have been on T3-Only for over 20 years and I have zero FT4 and zero rT3 in my system and I am very healthy. There are many people who have had to resort to T3-Only for a variety of reasons and as long as it is dosed correctly it works perfectly and safely.  There is a lot of misinformation that comes from both doctors and patients regarding T3-Only. Many doctors categorically state that T3-Only is dangerous and causes heart problems and/or bone loss. This is absolutely not true when it is dosed carefully and with a safe protocol.

4. Your doctor may not be fully aware of all the intricacies of how the thyroid system works. 

a) Thyroid hormone works hand in hand with cortisol.

Cortisol enables the thyroid hormone to have its proper effect. Thyroid hormone enables cortisol to have its proper effect. If a thyroid patient’s medication dosage is raised but cortisol is not high enough, the consequence can be that adrenaline is made to compensate. This causes unpleasant symptoms of anxiety and rapid heart rate as well as other undesirable effects. It is also likely to leave you with hypothyroid symptoms. Testing cortisol with a 4-point saliva cortisol test that includes Dhea Sulfate is important as well as an 8:00 am morning cortisol test. 

b) Adding more thyroid medication (T4 or NDT or even more T3) sometimes doesn’t actually raise FT3.

TSH often lowers when thyroid medication is added. Lower TSH causes fewer deiodinase enzymes to be produced in our cells. These enzymes are necessary to convert T4 to T3. So, lowering TSH may lower the conversion rate. It is common that after a raise of any thyroid medication (even adding a little T3), the person often feels an immediate improvement, only for this to go away after some days due to the lowering of TSH. In this case, the thyroid medication needs to be increased further in order to increase the FT3. Sometimes the balance of T4 and T3 needs to be adjusted so that there is more T3 in the person’s medication, and possibly less T4.

Sadly, many doctors just tell you that the raise of medication was not needed, or that, as they suspected, adding extra T3 was not what you needed! In actual fact, it was exactly what you needed but they did not understand enough to follow through with either further testing or a more informed use of thyroid medication. 

5. Your diet is causing some issues that are interfering with treatment.

a) Vitamin, mineral and other issues.

Hypothyroidism is notoriously linked with low nutrients like vitamin B12, Vitamin D and iron. In some cases, this is simply because a person who is hypothyroid cannot absorb nutrients in the same was as they did when they were healthy. The stomach and gut are made of cells. Since all your cells are hypothyroid, the digestive system is also operating less efficiently than it used to. In other cases, because the hypothyroid patient is struggling with weight problems, they may have restricted their diet somewhat and made it more likely for them to develop deficiencies and/or blood sugar issues. Testing essential nutrients like B12, Folate, Vitamin D and serum Iron and Ferritin are always a good idea. However, beware of your doctor just saying that your results are normal – see point 2 earlier in this article for more information on this topic. 

If someone is concerned over a weight issue, I would be careful about just eliminating carbs from your diet in order to lose weight. This may lead to low blood sugar and feeling even more ill than you did to start with. I think a ketogenic diet can be helpful for some people as it keeps carbohydrate intake low but keeps good quality fat and protein up to provide steady release blood sugar. In general though, try to seek out the help of a competent nutritionist / diet expert who can help you maintain a good intake of essential nutrients and energy providing food. 

b) Allergens and autoimmune reactions.

Diet can also be instrumental in reducing allergens and may in some cases help to reduce autoimmune responses (via anti-autoimmune diets). I am not going to write more about this, as there is plenty of information out there on the Internet and in some very good and well-known books.

6.  Sex hormones are imbalanced or low, or some other issue is at work.

Sometimes, when the basics have been thoroughly explored, and you know you’re on the right thyroid treatment for you, it may be necessary to look at other reasons for any remaining symptoms.

7. You may have been told that there is nothing else that can be done!

This has happened to many patients that come to me for help. It happened to me too! 

When I was at the end of my tether, and feeling like I might be an invalid for the rest of my life, I was told that I would have to live with my symptoms. I was told that there was nothing else that could be done. My endocrinologist told me that I would simply have to accept that this was what my life was from now on. It was a big fat lie! It was misinformation that could have condemned me for the rest of what may well have been a short life.

The bottom line is that there is always some valid reason for thyroid medication not working well and leaving you with the symptoms of hypothyroidism. It is not that, “thyroid medication does not work for you for some reason”, or that “you are a complex case”. It is just that your physician has not got to the bottom of the cause. 

This is why I strongly believe that every thyroid patient must be his or her own advocate. Patients need to learn enough, and know enough, in order to argue for themselves and put themselves ‘in the driver’s seat’ when dealing with their health. By being in the driver’s seat I mean that they know enough to discuss their situation with their physician and hopefully influence them to do the right thing. If this is not possible, at least you as a patient will know that you need to switch doctors.

It is risky to just hand over your health to your doctor and simply expect them to fix you. It can work in some cases but often it just doesn’t.

Sometimes it can be a struggle to get well. I know this from protracted personal experience. It took me 10 years to recover from incorrectly treated hypothyroidism that turned me into an invalid, stuck with the label Chronic Fatigue Syndrome (CFS). It took me several more years to get fit again. I lost all my thirties and early forties due to the incorrect treatment. I also lost my career. Moreover, the personal cost due to damaged relationships has been intolerable to bear at times. I do not want that to happen to others. I really don’t!

About Paul Robinson

Paul is a thyroid patient advocate at Paul Robinson Thyroid who became ill with hypothyroidism in his late twenties. He was eventually able to recover using T3 replacement therapy. He is now sixty, has written 3 books: Recovering with T3The CT3M Handbook, and The Thyroid Patient’s Manual.


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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. Michele Martin says

    I have had thyroid issues for about 20 years. I was always told my numbers where correct and I must be depressed or going through menopause. Finally saw a gynecologist who said I needed thyroid medication. Started at 25 mg and 6 months later it was increased to 50. Have been on that for about 12 years but now I’m experiencing those same symptoms that I experienced before taking medication (synthroid). Again I’m getting the depression remarks. How can I get help with this? Any suggestions would be appreciated.

  2. I had a thyroidectomy in 2013 and my issue has been weight gain and difficulty in losing it. I’ve been placed on levothyroxine 125 to 150mg back down to 125. I had a cortisol test and it was normal. Other symptoms are dry skin, breaking hair, fatigue etc. I’m now 68 yrs. Old so maybe the doctors feel like I’m going to have these problems anyway. Although I see an endocrinologist, how do you know when you have a doctor who is really interested in your concerns? The ones I’ve seen are just like the ones in the article. I’m in the East Orange, NJ area and if anyone is aware of a good Endocrinologist please let me know. Thank you

  3. I’ve been taking levothyroxine for the last 5 weeks and feel rubbish I keep having hot flushes feeling sick dizziness and palpations ts baking my anxiety worse too I’m actually thinking of not taking my meds this morning can anyone tell me if all this is normal please

  4. This is all wonderful information. How do we find the right physician to help with this, though? I’ve been to endocrinologists, Internalists, and a psychiatrist was the only one who gave me a complete thyroid panel. I live near Omaha, NE. Do you know if any good physicians nearby or what type of physicians we should be looking at?

  5. I am 8 weeks pregnant and found out I have hypothyroid , anemia , vitamin d deficiency, I am put in thyroid meds and supplements for iron , vitamin d .. I am petrified about my baby

    • Don’t be petrified! A good prenatal will cure a lot of that, we all need the extra iron for sure. The thyroid levels will be monitored safely for the baby. Our bodies naturally need more thyroid hormone and generate it during gestation. You just need a little help. Try a yoga class that’s approved for pregnancy so you can get the relaxation you need.

      I had taken radiation to ablate my thyroid 6 months prior to pregnancy, just outside the window of safety and had an awful time. The increase in thyroid hormone I had to take was to mimic the body’s natural response. (I no longer had a thyroid) They constantly took labs and I had 3 ultrasounds. She was fine. The worst of it was how long it took to get “normal” after the pregnancy, but she was fine. Stay cool and enjoy the ride.

  6. Cheryl Cantilli says

    I was just started (1 week ago) on Armour thyroid meds 30mg every other day for 2 weeks then to increase to every day. I have been dealing with anxiety since August and in January figured out it’s hormonal (menopausal). I’m on estrogen and testerone pellets and progesterone. My problem is that I still have the jitters. My dr says this will go away. Using Clonazapam to control it.
    What is your experience? Will it go away. How long does it take to get used to the med ?

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