Thyroid UK
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Do I need to reduce T4

I have read several times of people who say they react badly to T4 and convert to only taking T3. I'd be most interested to know how they work that out. please let me know if you have had a bad response to T4. For the last two months I've been taking daily 10mcgs of T3 in 4 split doses and 50mcgs of T4. I have had some improvement but am still far from well. How do people know they are reacting badly to T4? Is the only way to reduce the dose of T4 and increase the T3? I'm seeing my endocrinologist in a few days and want to know if I should suggest this as a way forward.

5 Replies

I felt like I was being poisoned. I had severe joint pain, brain fog, depression and goodness knows what else. I tried NDT and felt better to start with but as I increased my dose to combat the hypo symptoms, the same feelings of being poisoned returned. I don't get this on t3 only. I just get hyper symptoms if I am taking too much (which isn't pleasant but is very different).

It is important to look into why t4 isn't making you better or is making you worse. Low iron or low or high cortisol are the most common reasons. It is also important to make sure everything else is ok. Deficiencies in vitamin D, vitamin b12, folate etc could be causing the symptoms. It is wise to get all of the above tested. Don't rely on the reference ranges. Some are far too wide. Post then on the forum and someone will be able to tell you if supplementing might help :)

I am hoping to be able to add some t4 back to my treatment regimen now that I have sorted out some of the other issues. For me, t3-only treatment was a last resort.

I hope that helps a little.

Carolyn x


T4/levothyroxine tends to cause intense muscle and joint pain

even t3 can do it if you are chemically sensitive

The situation appears to occur in those who have central/2ndary hypothyroid but that's only my impression and experience of my husband,daughter and granddaughters

all of them cannot tolerate levo or t3 but are much better on NDT


I do believe that those with a low TSH don't do well with t4. TSH is involved in the conversion process so this makes sense. As well as those with central/secondary hypothyroidism, this would also apply to those with a low TSH due to other causes such as adrenal issues. I also remember reading that low b12 and low iron can cause low TSH (can't find the article now).

I'm hoping that on improving adrenals, iron levels, b12 etc I have improved my TSH response and will be able to add some t4 back in. If I now also have secondary hypothyroidism, I guess I'll be staying on t3 only.


Arty, I felt poisoned and ended up 90% bedridden with breathing problems, palpitations, musculoskeletal pain, tremors etc. I had to come off Levothyroxine for 4 weeks on 2 occasions and felt improvement so I was sure it was Levothyroxine. In the end I came off it for 12 weeks to clear any build up but symptoms started within a day of resuming Levothyroxine. I added T3 and it calmed down the symptoms Levothyroxine caused and improved my low FT3 too.


I don't think you are on a high enough dose of thyroid hormones altogether. If I read your question right, you take 50mcg of levothyroxine (T4) and 10mcg of T3 (split into 4). This would amount to around 90mcg of levo which is quite low.

Have you had a recent blood test? If not, ask for one to be done and get a print-out with the ranges and post them on a new question. Don't take any thyroid hormones before the blood test, which should be as early as possible.

I didn't split my dose of either levothyroxine alone, T3 and T4, or T3 alone which I am on at present and well. There is no need to split the doses of T3 as I found it calmed by whole system down and our receptor cells need to be saturated with T3 the effect of which lasts between 1 and 3 days for a single dose but it has to be sufficient. T4 is helped to convert to T3 by taking Vitamin C. This is an excerpt from the following link:

Dr. Lowe: As a rule, our patients take thyroid hormone only once per day. An advantage of this one-per-day schedule is that it’s easier to find a window for good intestinal absorption—when the stomach or small intestine doesn’t contain food.


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