Thyroid UK
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T3/4 advice please


My endo agreed that I could trial t3 and for the past 3 weeks I have been taking 20mcg liothyronine and 75 mcg levothyroxine. The t3 dose is split into two doses and I was previously taking 125mcg levothyroxine.

My brain fog has lifted and my burning feet/ myalgia has improved but overall I feel worse - more fatigued and even less stamina than before.

Does anyone have any advice? I would say I feel under medicated but could this be the case? Or might I simply feel worse before I feel better?

My b12 is optimal as is vitamin D. My ferritin is well within range but not quite optimal.

Please help. I was so hopeful that the t3 would help and feel nothing but despair at the moment.

10 Replies



The sequence of events (as I understand it, and I might have got the wrong end of the stick) :

1) Add T3 to meds.

2) TSH lowers in direct response to the T3.

3) With lower TSH the conversion of T4 to T3 is lowered.

4) With lower TSH the amount of reverse T3 created may increase.

If you've been unable to convert well from T4 to T3 for a long time your reverse T3 levels may already be high.

I take T3 only. At low levels my fatigue was extreme. I could fall asleep in an instant if I sat down. My brain fog got worse, my vocabulary worsened. Things only improved when I increased my T3.

The chances are that you may need to :

a) Increase your T3.

b) Reduce your T4.

c) Do both. But you should only change one thing at a time otherwise you won't know what has made things better or worse.


Thanks. It's so hard to know what to do. I don't have an appointment to see the endo until October and I'm fairly certain that my gp won't know what to do.


I have always taken my dose whether T4, T4/T3, NDT or T3 only (what I take now) once daily and have always been fine.

Dr Lowe's patients always took their dose once daily. T3 is needed to saturate all your T3 receptor cells and sometimes T4 doesn't convert sufficiently.


These clinical and experimental findings argue against that idea of "cycling" enabling patients to maintain improvement after stopping their use of T3. With increases and decreases in dosage, the only thing that has cycled in our patients is their fibromyalgia status. So, do I believe that "cycling" will "cure" cellular resistance to thyroid hormone? Unequivocally, no!

Third, the leaflet on Cytomel pharmacies give patients when they fill their prescriptions states, "POSSIBLE SIDE EFFECTS: NO COMMON SIDE EFFECTS HAVE BEEN REPORTED with proper use of this medication." This information is accurate—when plain, full-strength, one-time-per-day doses of T3 are used properly, there are no adverse effects


Thanks for your reply.

May I ask how you came to be on t3 only? I feel like the combo that I'm on at the moment is in some ways better than levothroxine but not sure how to improve it.

While my endo is one of the better ones in that he did listen to me and accept that I was well informed enough to make a decision about my treatment I think he is expecting the t3 to fail and I don't want it to!

I think I'll take all the meds together tomorrow and try to see if any difference works.


I've just read your profile and I can see how you ended up on t3 only :)


You may want to see if you can get onto Armour or Erfa as a named patient on the NHS (which is the desiccated pig thyroid that contains both T3 & T4) . Also--any changes in meds seem to take awhile to reach stability, so give it time. I was first diagnosed in the US with Hashimoto's and put on a T3 --only regime. Dosages were raised 5mcg at a time so I'd acclimate. Later T4 was added as well. Over time I found that I do best on a combo of t3 & t4 and even better once I started taking the entire dosage in the AM rather than splitting the t3 into two dosages. Everyone is different -- so be patient. I come from a large family where we're all afflicted with autoimmune thyroid disease -- BUT everyone's symptoms and treatment are different.

Good luck.


I know NDT is a non starter in my health board as it's just not prescribed by any endos - not even privately. I would have to self medicate and I don't feel strong enough to head down that route.

I have been on t4 since April 2014 and reckon I have been hypo since at least 2008 but was constantly fobbed off. It's so frustrating.



Tealtension, 3 weeks isn't enough time to judge whether T3+T4 combination is working for you. You've had some improvement which is good and it's likely you will have more 6-8 weeks after starting T3. Symptoms can lag behind good biochemistry by a couple of months but you should be able to tell by Sept/Oct whether the addition of T3 is beneficial.

If your FT4 was good (in top quadrant of range) on 125mcg it's usual to reduce T4 by 50mcg when introducing 20mcg T3. It actually gives you the equivalent of 10mcg T4 dose increase.


My t4 was near the top of the range and TSH was 0.5 before starting liothyronine.

I am hopeful that I will feel improvements but I was rather concerned that I was feeling an increase in some symptoms and was really wondering how normal or usual it is. Or if it was a sign that something else was wrong.


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