Thyroid UK

To take Carnitine, or not to take Carnitine with hypothyroidism?

Just trying to decide what is the best thing to do here.

I have the diagnosis of being hypothyroid (18 yrs) and of ME/CFS. I happen to believe that there is more going on than the thyroid and adrenals, though I know some people on these forums don't agree.

At any rate I am trying to address all issues and trying to improve...... been at it a few years now!

I had the Mitochondrial Function Profile done by Dr Sarah Myhill around 4 years ago, and came out with the lowest score for Carnitine ever recorded. I was a bit puzzled as I have always eaten plenty of meat (red and white), and so of course there must be a problem going on here that's not just to do with intake. I was advised to take Acetyl-l-Carnitine as well as other supplements, but at the time could not tolerate it due to stomach issues, but that's improved now and I can tolerate more things.

Then I read about the research done that seems to point to a problem with Carnitine if you are hypothyroid (OK if hyperthyroid). I keep meaning to ask Dr Myhill about this and will do so, but I know I may have to wait a while for a reply.

I am actually on T3 now not T4 and although this is trickier than T4 as I take it 3 x a day, do you think it would be OK to take Carnitine if you take it away from the T3 dose? Just a thought anyway.........

14 Replies

Hi Acapanthus,

That's really interesting ..... I'm a long term user of ALC because of near identical problems to you, and I had no idea.

I will also await any replies with interest ... Thanks for the heads up!



Unfortunately it seems that I would get charged by Dr M just to ask this question. I had hoped that as Carnitine was such a mainstay of the ME/CFS treatment that she might address it as a general question as there must be many with thyroid issues who consult her. Maybe it will be addressed at some point in her online advice book as I feel sure someone will raise it.

However as I am more recently seeing a Dr F in London on similar issues, and have been advised to take Carnitine by him also I am trying to now address this with him. I will post anything of use on here.

1 like

Thank you! As you say - its a mainstay treatment for a lot of us with CFS/ME ... And a lot of us are also hypothyroid!


Well I have had a response from my London Dr. It seems clear that he did not know of this research, and I have had a bit of a non committal reply throwing the ball back in my court for now. This is what he said in's basically his summary on l-carnitine.....

'L-carnitine is a non essential amino acid that is biosynthesised from the essential amino acids Lysine & Methionine. L-carnitine is essential for the transport of fatty acids into mitochondria for energy (ATP) production, normal growth development, thermogenesis of brown adipose tissue the regulation of gluconeogenesis. L-carnitine insufficiency may therefore result from inadequate protein intake (and specifically that of Lysine & Methionine), impaired intestinal absorption, increased protein losses (in urine, stool or from loss of blood or plasma, etc) or possibly impaired L-carnitine synthesis. The main dietary source is from meat (1st mutton, 2nd lamb, then beef & pork, then white meats). Vegetarians quite frequently have low levels of Lysine and L-carnitine. We quite commonly find that a fair proportion of CFS sufferers have low plasma L-carnitine and a proportion of these find L-carnitine supplementation helpful. If low plasma L-carnitine is found or suspected, the causes should, as far as possible, be identified and addressed, eg. inadequate dietary intake, digestive issues, etc. A trial of L-carnitine may be helpful in the short term.'

So the thing is that there are different reasons for deficiency of l-carnitine. In my case I recorded about the lowest level that Dr M had ever seen and yet I have never been a vegetarian and have quite a high intake of meat. My guess is that at the time my gut issues were part of the reason, and maybe I also have impaired L-carnitine synthesis. If it was the latter then presumably just adding in more of the supplement is not going to help.

I am inclined to give it a miss actually......


How are you doing now? Did you take the l carnitine? I think my son needs it but I am worried about affecting his hypothyroid. Thanks for any input.


Hi JPotter. I am doing much better thank you now. In the end I was not able to take l carnitine as it affected my gastritis too much, and gave me severe stomach pain though I tried a number of times.

I don't know where you live but there is a test here in the UK that can be taken privately via a practitioner that checks for carnitine levels, (Acumen lab does it here, I don't know if anyone else does it), and I did have that done first which showed my very low levels. Otherwise it's all guesswork. I then had it rechecked some 4 years later and my levels had increased pretty well without any supplementation. Carnitine is especially in red meat, so it would be good to ensure that your son has adequate supplies of that, as I am a red meat eater, and no doubt my levels went up as my general health improved.

I did get some advice via Dr Myhill in the end - in her opinion carnitine is so important that she believes that in spite of the research re carnitine and hypothyroidism that if it is known to be low then it should be supplemented, otherwise the person will not get better. If it then affected the thyroid output then this could be corrected 'downstream' - presumably by taking more thyroid meds to compensate but with the advice of course on this of a Dr. This is only my own summary of her advice though, so don't take it as gospel.

However, as I said, my own carnitine levels (the lowest on record as far as Dr Myhill is concerned) came up without supplementing, though it may well have taken longer.


Agapanthus, would you mind if I messaged you to find out a bit more about Dr F please? I am hypothyroidism, but increasingly suffering from fatigue and problems with the medications.


Hi Sassicat,

No problem. If you drop me a line via pm I will let you know more details of the Dr I was seeing.


Hi, just a little information that it seems might be missing here.

I work in alternative medicine/ homeopathy, I treat thyroid often (over 20 years) and l-carnitine is often used in hyperthyroid/ grave's disease due to it's suppressive qualities. (Please do not do this without medical support, I'm just offering this informationally.)

This is not a supplement I would normally just have a hypothyroid client take, especially someone with hashimotos. I hope that is helpful. Please be careful with this one and also tyrosine, while they can both affect the brain positively, if you are sensitive with your thyroid, you may cause issues in function.

Everyone is unique, we all must find our own path, hope this offers some additional information in finding yours. Blessings, Jen

***This is not meant to be medical advice, rather educational/ informational. Please seek medical attention when necessary.

1 like

I'm being treated for CFS, mitochondrial dysfunction, Hashimotos, etc. by an expert doctor synthesizing the latest research.

I've been taking all the mitochondrial supports Dr. Myhill recommends, including IV carnitine and oral acetyl-l-carnitine, as well as a lot of methylation support (Bs, etc.)

I ended up tripling my T3 dose over time - can't take natural due to allergens and T4 wasn't converting. So, it's a matter of balancing.

The things that have helped me finally turn the corner, though is a combo of Garth Nicholson's lipid replenishment and PolyMVA.

A multifaceted approach is what works and the "devil is in the details" of balancing everything.

So, please don't warn people off a supplement without taking a more comprehensive view.


Haha I have hashis and I just took acetyl carnitine twice. CoQ10 is apparently good for my sense of well being so I read about carnitine having a similar mitochondrial function.

Had to read the article three times before I realized it said may lower thyroid. Whether something raises or lowers thyroid the warning always says don't take it. I don't trust the doctors assessment of my condition. It's gotten to the point where I don't know what warnings to trust. I have never heard any why behind this concern that I read in Web MD was just like "some" concern or something like that.

What were the facts even?


Hello :) I was wondering if you continued to take the l carnitine. I am thinking about taking it but after reading all of these posts I'm worried it may do more damage than good. I too have Hashimoto :(


Hello Leopardiva

In the end I did try to take Carnitine orally, but I have a difficult problem with my upper stomach in that it reacts severely to some foods/medicines and I end up with acute pain. Carnitine was one of these things so it kind of decided me at the time.

However I now do use some Carnitine, but have developed a way of using it transdermally. I don't know how much I am getting by this method, but thought it would be less than orally as I can only put on a very limited amount. I buy transdermal magnesium oil from Dr Myhill and add the Carnitine powder to it, and rub it onto my feet and sometimes my legs. The mag oil contains DMSO which is supposed to help carry substances through the skin.

Also I seem to recall re the research with the thyroid issues and Carnitine that it inhibited the T4 to T3 conversion. As I now take T3 only then there is no conversion going on so presumably it should not affect things. Also if I use the Carnitine transdermally and the T3 orally then maybe that would not be a substantial problem anyway.


how have you ladies got on with the Carnitine. My nutritionist has recommended it because of my mitochondrial dysfunction. I have also read on WebMD to not take it if you have an under active thyroid (which I have and Hashis)


You may also like...