Anyone else have cognitive deterioration, poor coordination after raising t3?

Did anyone feel worse (cognitively, physically) when increasing t3? I felt so well when I first introduced it into my regimen so I associate it w strength and stamina, but I'm not getting any of that right now. I wonder if maybe this just isn't for me and I should go back to my usual levo/t3 combo.

Over time since March I've gone from 75/100 levo + 10 t3 to 25/50 levo and 25 t3. I feel like my head is not working at all. I just can make no sense of any series of tasks, I am having more trouble than ever prioritising. If I have three things to do in a row I will do one and forget the others until something prompts me, and then I may cycle through the same process of forgetting and remembering a few times before it gets done. It's hard to explain, I can only imagine this must be what it feels like to be a goldfish. I also felt this way when I tried low carb.

It is not impossible that I'm just underdosed right now but every time I raise t3 I get some hyper symptoms and I really hate that so I'm going slow.

Also struggling w typing (making loads of mistakes) and other physical tasks. Have fallen down out of the blue - ! - and mis-stepped on stairs I use dozens of times a day. Feeling weak and feeble, definitely worse than usual.

The improvements I can see are that in general my mood seems a little better (when I'm not freaking out about how badly my brain is working :-) ) and my colouring seems much better than usual. When I was diagnosed I was so pale I was almost grey, and levo helped return some colour to my face. Now on mostly t3 my face looks properly peachy. (I'm also taking iron which might be helping.) Hair loss also seems to have slowed.

34 Replies

Yes, the brain wasn't designed for such high levels of T3. (Ask any Graves' patient.) I personally have no short-term memory and can't do math if my T3 dose is too high. Have you seen this? It talks about what you're experiencing.

How much T3 is too much?

I think if you read any thyroid forum, the answer is, it depends. I think I've read some people take 150 mcg T3 daily, others say they feel fine on T4-only. But we do know, that on average, a normal thyroid gland secretes about 6-10 mcg T3 daily. You just have to experiment to find your optimal dose.

Do you know of a way to cut the 20mcg tablets into quarters successfully? I am really well on T3 but am needing less, on 10 twice daily now but think I need 5 x 3 times. The tablets are very friable. I don't want to be dissolving and mixing every day. What do others do?

Hi Puncturedbicycle

- what you're experiencing can't be much fun. When you say March, do you mean March last month? So depending on when you started in the month could be 7 weeks or even 4 weeks that you've been on this new regimen? Perhaps that really isn't such a long time to get from 10 -25mcg? By how much do you try and increase t3? Maybe as little as 3.25 could be the answer to avoid the hyper symptoms? I am on t3 only, 87mcg, and found that I needed very small amounts when increasing, particularly after 50mcg. It took a long time - nearly 9 months to get to this dose ( though you were already on t4/t3 so my experience shouldn't be relevant.) I feel very good at 87mcg - brain included. My muscles are strong too though when on less dose I suffered problems with missing steps such as the ones you describe and difficulty processing complex information.

As you say you may well be underdosed - what about bloods? I suppose now is about time to take a look?

I find, btw, the website HIFL refers to very critical of T3 so rather unhelpful - "Barb" seems very fond of barbed comments in het comments section. Having asked for experiences to be shared, anyone who reports a positive t3 experience is made to feel very unwelcome! The one paper cited is not concerned with the use of t3 at all and thus the conclusions are erroneous.

Yes, was on 15 t3 for about four weeks (I think 50 levo, can't remember off the top of my head but it is recorded in an earlier post), all well but I was advised here that I was underdosed. Could not raise to 20, I went hyper after four days, so I reduced levo again and then was able to raise t3.

For the first time my temp seems more normal (has always been low but now often reaches 37 in afternoon), heart rate is same as usual (at rest is it lower than usual).

It is not much fun! But I am desperate to boost my energy (er, that would be a fail then). I'm losing years of my life to exhaustion. Just thought it was worth swapping some meds around to see if there is any improvement, and you know what it's like, you have to commit to a certain period of change or you end up where you started.

Tbh this does not feel like ordinary hypo. I get tired and muzzy on a low dose but not this kind of goldfish brain.

Is it possible there are just 3 different human physiologies, and caters to the T4+T3 group? If you belong to that group, but are advised to be on T3-only, your results are like what puncturedbicycle is describing--more T3 will make you worse. Likewise, if you belong to the T3-only group, and T4 in any form makes you ill, then being advised to take any form of T4, whether NDT or T4-only, will also be bad advice.

There was a recent post from diogenes about a study that said T4 had an essential role in brain health ( That confirmed everything I've felt on various doses of T4, from high to low, though what I "feel" is obviously subjective. I NEED T4 for my brain to work properly. Your experience with T3-only sounds positive, but mine was negative. I don't think either of us is wrong, I think we're talking apples and oranges, or about two different biological physiologies.

I believe this is the way our health care will evolve, looking at the way we are different, maybe on a genetic level. The problem is that right now we don't have that info and the only way to tell is by trial and error.

My doc said I'd be fine on t4 only and I found out that was not true, but I only knew when I tried t3. How did you find out you needed some t4? You say you've been on various doses. That's what I'm doing w t3, trying to see what different proportions of t3/t4 do for me.

I wish the solution was obvious but I didn't feel well on my previous dose of t3/t4. Idk if that's as good as it gets until I've tried other options.

I didn't think catrich was saying anyone was wrong but some websites do take a very dogmatic view on various stuff (STTM and ndt come to mind) and it seems catrich felt unwelcome there.

Indeed - not saying any one was 'wrong' - far from it. The website referred to, on the other hand, seems to have an underlying anti-t3 agenda. Reading the Comments is quite entertaining. Thankfully this forum is so different. Opinions and experiences are shared and, for the most part, received in the spirit in which they were given.

The main thing I noticed with a higher T3 and lower T4 dose was brain dysfunction. I couldn't remember things while I was still doing them! Did I just salt my food or not? But I was still talking, walking around, and driving. It was a kind of dizzy feeling (not literally dizzy), but more like an airhead lol?

Have you read the tiredthyroid page on T3 and T4's role in the brain? The 4th paragraph seems to describe what you're experiencing--difficulty completing any task that requires thinking.

It seems there are 4 dosing protocols out there and if your physiology is similar to mine, you'd follow a certain order. T4-only, then NDT, then MORE T3 (until you realize you can't think anymore), then backing down and adding more T4. I ended up on T4 + NDT because FT4 was so low on NDT when FT3 was already towards the top of range. I think if someone has these particular labs on NDT (low FT4/high FT3), that is a good indicator that they'd do better on a T4+NDT combo. I can't fathom why, if FT3 is high, other patients would recommend MORE T3?

Maybe those doing well on T3-only can say what their labs were like on NDT. I would guess their FT3 would be low on any dose of T4 or NDT? If that were the case, then results on NDT would be a way to separate people into these different physiology groups.

Thank you. I can't make any sense of that right now but will read later.

I may miss out my evening dose of t3, or halve it, just to see if my brain feels better.

HIFL just another thought, when I started taking t3 my doc said to stay on the same levo and eventually my t3 went a little bit over range, not by much (I want to say the range went up to 6.3 and I was 6.8, something like that). I had begun to have symptoms like diarrhoea and feeling a bit snappy, but otherwise it was magic, I felt amazing.

Thinking back, I was on the highest dose of levo I have ever been on (150mcg) which had got my tsh below 1 and t3/t4 in the upper part of the range, but there must have been a smidge of wiggle room which is why the doc added 10 t3.

Down the line, after finding out I was a little overdosed, doc suggested I begin to reduce t4 in alternating doses to try to preserve the feelings of well-being, but before I got a chance to do that I crashed and a lot of symptoms returned (constipation, feeling tired etc).

I always wonder what happened there, was that a sudden rt3 because I'd gone over my body's limit? My t4 has never been so high in the range again, I guess because although my t3 dose has stayed the same, my levo dose has come down over the years to accommodate the ever receding tsh, which over time has become very low due to the t3 I guess.

Just musing on this because if you and I are alike and require a certain amount of t4 in our systems I wonder how I'd get back there. I'm sure I don't understand what you're getting at w 4 dosing protocols, but if what you mean is that I should try ndt (in addition to or instead of levo?) I wonder if that is the way forward. I've tried ThyroGold but went very hypo after having mixed hyper/hypo symptoms on it.

Writing a tome as always, sorry. :-)

So you felt pretty well on 150 mcg T4, and now you take 25/50? That's a pretty drastic reduction. I get diarrhea and snappy when my dose is too high. Maybe you just had to reduce somewhat, like from 150 to 125 or 100, when adding the T3. To get back to where you were, you'd have to slowly reduce T3 while adding T4 back in. Or combine NDT with T4. Whatever you do, don't use TSH as a guideline.

No, sorry, I meant over a period of about three or four years the levo has been gradually reduced (I was on 150 about four years ago and yes, the plan was to reduce levo on alternating days but I crashed before I started doing that, as above). For a while for whatever reason my tsh was suppressed and t3 was fine, this happened at every blood test and I wasn't feeling well anyway so saw no problem reducing. I think I have had a problem w my levels fluctuating (my ABs are always high). My results below were on 75/100 levo and 10 t3.

I have tried to raise my t3 in the past to get it higher in the range and I never feel any better, just hyper. Just wondering if the key is getting both t3 and t4 higher in range (like when I was feeling better), but no idea if that is possible now.

HIFL just to update you, I reduced the t3 on Fri and began to increase my levo. I am now on 50 levo and 15 t3 and feel (today anyway) fantastic. The weird goldfish brain feeling has gone thank goodness.

Despite having had to get another long haul flight yesterday I went for a walk today and did a little bit of gentle running for the first time in forever. It was very gentle and really just to get my heart rate up but a few hours later I feel positively energised. I was bouncing on my toes in the supermarket and if it wasn't late and wet out I would have gone for another before bed.

Technically this dose is meant to be lower than my earlier dose of 75/100 levo + 10 t3, but I might just stick w it for a couple of weeks to see how I feel and if I remain well I'll see it out for six weeks and a tft. I am curious to see what the bloods might look like.


I found your post really helpful. I didnt know what to do with my thyroid levels. I have been completely debilitated by my failing cognitve ability. Cant string a sentence together, forget things while I am doing them etc. My T3 was over the range, and my t4 levels were very low. I have reduced my T3 and increased T4. Now we'll wait and see. I feel like crying. I have had to stop working because I couldn't talk or think properly. Hugs .

Hope you start to feel better soon.

There seems to be some confusion as to the relative strength of T3 to T4, varying from three times and four times. Taking it as only three times stronger, that means you were taking the Levo equivalent of 30+100 Levo, total 130, or 30+75=105., and changed to Levo equivalent of 75+25=100 or 75+50=125.

So your overall dosage has dropped slightly. Maybe the brain effect is due to that.

I am taking T3 only, and have no cognitive problems, (unless they are so bad I don't even know it....)

I wonder if you have made any other changes, such as low fat, or any other medication or supplements changed? I am sure you would have mentioned it, but just asking.

25 T3 is not such a massively high dose, I am taking almost double that, with no T4. Of course, there is a possibility that you are converting the T4 better with higher T3, but I am not convinced it would make so much difference, and since you are aware of hyper symptoms, it suggests you are not overdosed. Other than that, I can only say that maybe you went faster than your body can cope with.

Which version of T3 are you taking, may I ask?

I'm on Mercury Pharma nhs liothyronine, though yesterday I took a Grossman tablet (25mcg) to avoid having to break tablets into crumbs. I've used both for years. No other changes, dietary or otherwise.

When I change a dose I usually do calculations showing the spectrum of potential 'real' doses (translated into levo equivalent) and it looks to me like I was taking the approximate equivalent of 117.5 - 137.5 levo and am now on the approximate equivalent of 112.5 - 162.5, so as far as I can tell there is no real chance of being underdosed. I agree that I may be converting better (that has happened before when adding t3) and I know this isn't a straight swap, I'm just making educated guesses.

My body doesn't give a lot away (my temp and pulse rarely change very much unless I am very over- or underdosed), at least not immediately (if half my hair suddenly falls out as it did when I went hypo I will know something is up lol). I really should only adjust my dose in a lab :-) there is so little to go on when looking for direct and obvious signs. I have that slightly vibrating wired feeling that I associate w being hyper but in truth I'm terrible at this so I shouldn't guess. It is so hard when you already feel terrible to judge whether you're feeling more or less terrible.

Maybe I will order a fingerstick test. At least I'll get a snapshot and if I've gone wildly too far in one direction I can make an adjustment.

Puncturedbicycle, I'm the same, in that I can't very easily tell the difference with changes in symptoms. The main thing that's been a yard stuck for me is how long I can comfortably stand up, but of course that varies wildly across days and weeks.

Rereading your original post did make me think of one thing I've experienced as I've increased my NDT. I went through a phase of tripping over my own feet a lot. But it was accompanied by having a bit more energy. My interpretation of it was that I could now move faster, but my ability to make the judgement and coordinate my limbs was lagging a bit behind.

Quite often I've had times when I get a new symptom or thing that sounds worse, but it's because things are getting better. Breathlessness is another. Before I could really move I had no reason to be breathless. Now that I can motor up the stairs of course I get breathless.

It would be nice if something like this explained your problem :)

Sorry, I'm bombarding you with random thoughts. At the moment my preferred way of changing between different formulations is to aim for a dose at the low end of matching the previous dose, and then be prepared to raise it after 6 weeks.

Mainly because becoming hyper seems to be too confusing to accurately detect.

I am very conservative, though, and take blood tests every 6 weeks before raising. It's paid off recently because I started seeing a new private doctor, and one of their first comments was 'you're probably on too much'. But I know completely confidently none of the previous doses were any better than my current one, and I have all the blood tests to prove they weren't over range. If I didn't have that I'd have felt there was a small chance they might be right.

No worries, your random thoughts are good ones. :-) I'm really grateful to hear from someone in the same boat. It can be hard to understand how I don't know if I'm high or low if your reactions are very straightforward.

I did something similar in that I reduced my levo to 50 and increased t3 to 15, and I stayed there for maybe four weeks, no change. Then I got worried about being underdosed (I really don't want to lose my hair!) so I tweaked it a bit (50 levo, 20 t3), went hyper (no doubt about it, my temp rose and I didn't sleep) so I had to tweak again (25/50 levo and 20 t3).

I had been on my former dose of meds (75/100 levo and 10 t3) for quite a while and do have recent bloods (from 13 March). Another bit of the puzzle is that my rt3 is a little raised here and I wondered if that's why I was so symptomatic, so I thought the thing to try was reducing levo.


Thyroid Function


FREE THYROXINE 16.0 pmol/l 12.0-22.0

TOTAL THYROXINE(T4) 100 nmol/L 59-154

FREE T3 4.8pmol/L 3.1-6.8

REVERSE T3 * 25ng/dL 10-24




Thyroglobulin Antibody* 376.2IU/mL 0-115

Method used for Anti-Tg: Roche Modular

Thyroid Peroxidase Antibodies * 234.1 IU/mL 0-34



Vitamin B12 136 pmol/L 25.1–165.0

Folate (serum) 7.9 ug/L 3.9->20.0

25 OH Vitamin D 50 nmol/L 50-200

Interpretation of results:

Deficient <25 nmol/L

Insufficient 25-49 nmol/L

Normal Range 50-200 nmol/L

Consider reducing dose >200 nmol/L


Inflammation Marker

CRP-High sensitivity 1.8 mg/l 0.0-5.0

Iron Status

FERRITIN 26 ug/L 13-150

Optimum Ferritin level for females : >27 ug/L

I've had reverse T3 at a similar level. It's now dropped just inside the range. I don't know how important it is :( I'd like to have tried T3-only to see if that helps, but ended up rushing past it.

I'm sure you already know that your ferritin and vit D are quite low.

Getting to the point of being definitely hyper is good news, I think. I've never experienced it, but I hope to someday soon :)

Eek, not good news, I don't like it. I was awake all night, heart racing. I ended up taking a beta blocker and an antihistamine to calm everything. I hate that wired and tired feeling.

There is a long story behind the ferritin and d, but as soon as the blood draw was finished I started taking them again.

I feel the same about the rt3, not sure if it was playing a role in feeling bad but trying to sort it all the same.

Good luck w your own health. Feels wrong to say I hope you are hyper soon - ? - but if that's what you're working toward... :-)

Hehe, yes I'm sure a terrible feeling, but great to have the line in the sand, and know you are working down from there.

I've had many a doctor tell me I'm on too much, but no real symptoms to back it up.

I agree that it may be a reduced dose. It's worth holding out for a blood test to see if that the case, and all you're experiencing is a return of some hypo symptoms.

Another possibility is that you don't mention splitting your dose. With T3 people usually split into at least 2, sometimes 3 or more.

When I started NDT I thought I would try not splitting, but eventually realised I was at my most tired in the early evening, so tried a 4pm dose as well as my usual morning dose. I got a great jump in improvement, more even than increasing a dose. The interesting thing was that it didn't just eliminate the groggy evenings, I also felt better when I first woke up in the morning, and my activity increased. So I guess I was really stressing my body out with peaks and troughs. And the funny thing is that NDT isn't supposed to have such a short half-life as T3, because it comes in large molecules that slow it down. I'm now trialing having 3 doses. I didn't get such a great bump of improvement when I started, but now I'm a little afraid to cut it down again - I know that when I take all my hormone in the morning before blood tests that by afternoon I feel as if I hadn't taken any. I used to be perfectly happy skipping doses for blood tests.

Yes, am splitting t3 dose into two, separated by 12hrs. Experience shows if I am taking doses of less than 10 I get a lot of symptom breakthrough, though that may only happen on lower total daily doses if that makes sense.

I think one problem could be that different parts of the body might need different amounts of T3. If the brain is satisfied with a certain amount of T3 before the body is then things could go wrong. And vice versa of course. And how much T4 there is will obviously have an impact as well.

I take T3 only. Since going on it my heart has improved enormously. I used to get dreadful chest pain. That doesn't happen any more. (I think getting iron levels up to optimal helped enormously too.) I'm still very weak and fatigued though.

I feel as though my body needs more T3 and my brain needs less. Which one should I satisfy? And I realise I could have misinterpreted what I'm feeling anyway.

It's a long time since I read this and I've forgotten most of it, but it is relevant and worth reading :

That's an interesting post. A pharmacologist friend was musing to me on things that might be possible with my condition. He did suggest that if I have thyroid hormone resistance different organs and cells might have different levels of resistance, so that parts could be overdosed while others were underdosed.

I thought that sounded like a bit of a horror story so hoped it wasn't true :(

I would love to be able to take NDT or even some Levo with my T3, but I seem to have issues with creating lots of reverse T3. I wonder if I had more T4 that it might get to organs which are deficient in T3 and then convert as needed rather than only getting what I give it in a pill.

My last Free T4 was 2.11 pmol/L (12 - 22).

I won't get much Free T3 out of that!

Humanbean, if you don't mind me asking, what kinds of numbers were you getting of rT3? Just over the top of the range, or higher?

The first result I got was after I'd spent a while on 100mcg Levo per day while following the late Dr Skinner's instructions.

It was 0.72 pmol/mL (0.14 - 0.54)

I tested again the following year having spent a couple of months on high doses of T3 to reduce the high reverse T3, then, after going very hyper, I took very small doses of T3 for a couple of months, then no thyroid meds at all for 3 months. After the no meds for 3 months my reverse T3 was

0.38 pmol/mL (0.14 - 0.54) which was 60% of the way through the range.

Thanks Humanbean, that's interesting!

How much is too much T3? Hard to tell since you can't really tell how much of the T4 is converting to T3 in addition to how much T3 is being supplemented.

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