A Small Number of Thyroid Patients Cannot Cope with Any Amount of Levothyroxine (T4 medication) in Their System

This blog came out of a conversation with a thyroid patient who was still having some issues when on mostly T3 with a little T4 in the mix. She had improved greatly with the T3 but was not quite at the point she wanted to be.

I related my own story to her. I simply cannot cope with even small amounts of T4 medication, e.g. even 5 mcg of T4 begins to make me feel ill with returning hypothyroid symptoms and signs after one week. This is the case even when my T3 dosage has not been lowered.

I have seen this type of situation many times before. It is very clear to me that some people simply cannot cope with anything but small amounts of T4, and in a few cases, any T4 at all makes them feel worse.

The thyroid patient then asked me about FT3, FT4 and reverse T3 results. She wanted to know if the above issue could still be the case even if the numbers were all within the reference ranges and rT3 itself was not high. She said she was only taking some T4 to keep her doctor happy because he felt that everyone needs to have some T4.

Laboratory test results do not explain everything. In fact, having ‘in range’ lab results simply does not work for some people who have more complicated thyroid hormone metabolic issues. Lab ranges have been developed based on a huge number of people. Those patients who have unusual issues may not feel well when their results fit into the standard reference ranges. Lab test results show blood levels of thyroid hormones. They cannot show exactly how effective the active thyroid hormone T3 is at the nuclear thyroid receptors and the mitochondria – there is currently no blood test that can show this.

Everyone needs to have enough T3 thyroid hormone working at the nuclear thyroid receptors. T4 does not do this. Only the T3 thyroid hormone does this, as it is the active thyroid hormone. For example, those people with absolutely dreadful T4 to T3 conversion issues may find T4 leaves them woefully hypothyroid even when combined with T3. Atrophic thyroiditis (AT) is another example of a condition that can make the use of T4 extremely difficult, as it often causes highly variable conversion rates of T4 to T3, inducing swings from hypothyroidism to hyperthyroidism (more information about AT at the end of this post).

I explained to the thyroid patient that I did not know that this issue was definitely what was holding her back, simply that it could be.

I do believe that this issue is one of the reasons why a small number of people never fully recover until the very last vestiges of FT4 and rT3 clear out. I have seen this work successfully many times with thyroid patients on T3-Only therapy. It is not a common issue but it does apply to some patients.

In my own case, over the past 25 years, I have tested whether I can cope with any T4 medication about ten times. I wanted to do this in case something had changed. Each time I have added even tiny amounts of T4 meds the same thing has happened. This is without reducing the T3 at all.

Here is an extract from Chapter 10 in the Recovering with T3 book:


There have been occasions when I wanted to discover whether anything had changed in the way T4 worked in my body. However, whenever I have attempted to use T4 replacement therapy again, it still failed and I quickly became very ill.

T4 still does not suit me – even in small additional amounts to my T3, e.g. 12.5 mcg per day of T4 is not tolerated by me.

T4 in any quantity brings back my hypothyroid symptoms. I am healthy, fit, active and symptom-free whilst on T3 replacement therapy. However, sometimes people express views like, “everyone needs some T4”. These types of views are stated from time to time, usually by doctors, but also, sometimes by thyroid patients. Unsurprisingly, the patients concerned are on some form of T4 based medication, and they think everyone else should be taking it too.

Sometimes this viewpoint is based on an old and not especially compelling piece of research that attempts to show that T3 cannot be used in the brain. Then they extrapolate from there that everyone needs T4. This is not the case. One of the big flaws in that type of argument is that people who are living well on T3 alone have not been studied for the very likely compensatory adjustments that the body makes when using T3 on its own.

The second big flaw is that more research is being found all the time to overturn old research. The ‘brain requires T4 research’ has just been proved wrong in fact. The new research is changing the entire understanding with its discovery of active transporters. [2] There are T3 transporters and they are more active in adult life. So, circulating T3 is a source of T3 for the brain. It is definitely not dependent on T4 in adults. Older assumptions are being proven wrong all the time. This particular assumption had to be wrong anyway – as thousands of people on T3 replacement therapy are well and healthy.

I have used T3 replacement for over twenty years. I know many thyroid patients, who have recovered their health using T3 replacement and have been using it for a long time.

T3 replacement therapy can be a very effective, safe, long-term thyroid hormone treatment.”

See this blog post on T4 not being required in the brain:

All of the above may seem a very heretical viewpoint to some thyroid patients who do very well on natural desiccated thyroid or a T4 combination. Even some who are on only a little T3 and rely on their own thyroid for T4 and T3 may find the above to be far-fetched. Well, all I can say is that I have lived my life in my own body and I know that the above is utterly true. I have also seen it in other thyroid patients who have near-miraculous recoveries when they are on T3-Only and have no T4 left in their systems.
We are not all the same. We have various issues. I am very pro-Levothyroxine (T4-Only) for those patients that convert it well to T3. T4/T3 combinations also work extremely well for many. This post is really just to make it clear how wide the spectrum of needs can actually be. I ask those that think the above is nonsense to simply not just think from their own experience.
We are not all the same. Some people cannot cope with ANY T4 in their system at all. It can be the thing that prevents them from recovering their health. Clearly, very poor conversion from T4 to T3 may be a factor for many in the same category. However, I do not rule out other more complicated problems, which may eventually become clear through research.

Finally, one big issue is that doctors and endocrinologists generally have strong views that FT4 levels need to be in range and T3 medication is not needed. For them, having no T4 meds or having any T3 meds is tantamount to having your window open at night and encouraging the Boogieman to come in through the window. They cannot cope with the notion of not taking T4 or of taking T3. They have been taught their views in medical school and are usually very rigid in holding this view. This is why some thyroid patients, who feel much better on T3-Only medication, get told by their doctors that they need to have some T4 (even if they do not seem to tolerate T4 medication well).

Until medical training begins to acknowledge some of the newer research regarding TSH and the importance of T3, and that thyroid patients are not all the same, then patients will still keep facing archaic views that keep many of them sick.

Best wishes,


In general, I still hold the view that T3-Only therapy is the treatment of last resort. I am very positive about the use of T4/Levothyroxine for a lot of thyroid patients who convert T4 well. T4/T3 combination therapy works extremely well for many patients. I just know that some thyroid patients need T3 with no T4 in order to recover. See this blog post for more details on my viewpoint:

Here is a blog post about Atrophic Thyroiditis:

Paul Robinson

Paul Robinson is a British author and thyroid patient advocate. The focus of his books and work is on helping patients recover from hypothyroidism. Paul has accumulated a wealth of knowledge on thyroid and adrenal dysfunction and their treatment. His three books cover all of this.

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  1. Dorathy Griffith on 11th June 2022 at 7:22 pm

    I have a question. I did feel better with your t3 protocol but don’t have complete resolution. Seems like I need higher dosing. How can I get help obtaining t3 more than 25mg tid? Also have to take Prednisone to function and dhea, low testosterone.

    • Paul Robinson on 12th June 2022 at 10:54 am

      Hi Dorathy, I usually recommend that people try asking other thyroid patients on thyroid forums for information on doctors or functional medicine doctors who will prescribe T3 or other solutions that they could look into. Your current dosage is quite low so I can easily imagine that you might need a higher dosage.
      Best wishes, Paul

  2. gailen on 12th June 2022 at 11:29 am

    Do you work with people to help them?

    • Paul Robinson on 12th June 2022 at 11:55 am

      Hi Gailen, occasionally yes. I have been taking some time off but then contracted Covid (again, courtesy of a relative this time). So, I’m not doing anything right now. If interested in the future then use the Contact Us form on the homepage of this website.
      Best wishes, Paul

  3. Maria on 13th July 2022 at 5:07 pm

    Hello from Germany,
    I hope you are better 🙂

    I take T4 for 10 years and never felt better or healthy. I have these hypothyroidsm symptoms since I am 14 (now I am 41) and this cannot be the way.
    My thyroid went from 6 ml to 3 ml in this 10 years and is labeled as “hashi seronegative” or “few peoples thyroid just shrinks”. I have no antibodies. So I am not even fitting in the AT category. I sometimes loose some issues for a few days when increasing the dosage but they return quickly, no matter the range of the lab. My TSH is always 0.01. I could swear there is nothing really intracellular. FT3 and FT4 conversion is ok. Do you have any idea what this sounds like? TYVM

    • Paul Robinson on 13th July 2022 at 5:52 pm

      Any thyroid volume less than 5 ml is likely to be atrophic thyroiditis. Hashimoto’s does not cause loss of thyroid volume – just fibrosis.

      Even an FT3 in the range may not be high enough for some people.

      If you have never tried T3 in 10 years then I’d say that you’ve waited long enough to switch to less T4 and more T3. Maybe even just T3.
      It can be a game changer.

      Low TSH will always mean that your conversion from T4 to T3 is minimised to the lowest it can be.

      It actually does sound like potentially AT to me. If this is the case T3-Only therapy is the best option.

      Good luck!

      Best wishes, Paul

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