T3 questions?

Hi everyone! I just have a few T3 questions.. if anyone could answer with their experience, I'd really appreciate it it! Thank you!!

Is it better to take the full dose of T3 in the morning or spread throughout the day?

How long do the effects of T3 last?

How long does it take to notice a difference with T3?

Are there any rules with T3(like NDT) where you have to wait a certain amount of time between eating and other meds/vitamines?

If so, what are they?

25 Replies

  • Thought you were taking NDT? :) Been about 3 weeks hasn't it? Just being nosey - why are you thinking of switching? It's a bit early to give up on NDT...

  • I have been feeling AWFUL, and I was thinking for a while what it could be but then after hours of research I'm certain it's because of RT3. My doctor unfortunately didn't test me for it, even though I asked. I come from a long history of eating problems. For the past five years I've been on clear liquid fasts more than I've had actual food. I've starved on 300 cals for months at a time. (This was not to lose weight btw, I have a lot of other health problems besides thyroid) anyway, I saw that's one of the main causes of RT3 and that NDT won't work properly because it contains T4 until I get that on track first. So I saw many people switching to only T3 when they have this problem and it working to solve it and make them feel better. That is my hope! And no worries about being nosy, this forum is like a family, I love it.

  • How's your iron doing? It can be uncomfortable tolerating T3 when your ferritin is low.

    What does awful feel like? I only ask because jumping from NDT to T3 may make little difference. If you haven't been taking more than a couple of grains of NDT I think it's unlikely you have high RT3 - you weren't taking any thyroid meds before that were you? How many grains are you on now, and when did you last raise your dose?

  • I have iron deficiency anemia and I'm working on it. Awful is feeling sick ALL day, not being able to get out of bed or function, sore and swollen everywhere, and just simply exhausted in every way. No, I wasnt taking any meds before. I was on 1 1/2 grains of NDT but switched to T3 only this morning.

  • How much T3 are you taking?

  • 1 1/2 tablets cause it's equivalent to 1 1/2 grains so about 37.5mcg

  • And how did that go? Bear in mind you'll still have some T4 in your system from the 1.5 grains of NDT.

  • Well It's only been half a day so I can't judge much just yet but I'll see in the next week or so any changes.Hopefully positive ones!

  • I had to try several NDTs before one suited me. Sometimes its fillers/binders which can cause problems.

  • Nessiam I'm not sure the NHS does rT3 testing, I may be wrong but it's probably more a test an endo would do rather than a GP if it is offered.

    You can get rT3 tested through Blue Horizon, either as part of their Thyroid Plus Twelve, I think it's also available as a separate test. You need a proper blood draw for a rT3 test.

    It would be best to know for certain that you have high rT3 before 'treating' it.

  • Agree. :) RT3 testing is sort of advanced testing, something to think about when you've got yourself up to a good dose of thyroid hormones but still don't feel better. It's a bit early to worry about it.

    I get the "read read read" thing. :) Been there. But patience is vital when trying to sort out thyroid problems. It can't be rushed cos if you do, you're likely to end up in more of a pickle than you were to start with.

    How much NDT are you on now? Have you been on it long enough to do any testing (6 weeks minimum on same dose).

  • You will see an explanation on this link about RT3 by a scientist/doctor.


  • How T3 is taken depends on the person. some do better taking it all at once, some feel better spreading it out. Some prefer to take it in the morning, some in the evening before bed. It's a personal thing, as is how long it takes you to feel better. No-one can answer questions like that, because it's all trial and error.

    Treat T3 just exactly as you would T4 or NDT - and hour before eating, etc. It is, after all, another thyroid hormone.

    As to how long the effects of T3 last... how long is a piece of string. People are always going on about its short half-life, but that's just the time it stays in the blood. That which goes into the cells works for a couple of days.

    But I'm not really sure what you mean by the 'effects'. What exactly are you expecting it to do? If you're expecting some sort of high after taking it, you'll probably be disappointed. It's no different to taking NDT. It should be a smooth ride from one dose to another, with no highs or lows. If there are highs and lows, it probably means you're not taking enough. If your problem is rT3, then you probably need to flood the receptors to begin with, to get as much into the cells as possible. Therefore, it might be best to take it all at once.

  • I'm sure it's a personal thing but i would still want to hear anyones answers to see what works for different people and have something to compare to, you know? I'll obviously end up going off whatever works best for me.

    Im not expecting to feel high.. just want to feel like a human 20 year old girl.

    Ah, I see. Makes sense about the RT3, I'll keep that in mind, thank you!!

  • It took me about five years, I think, to eventually get onto a dose/hormone which suited me. It's not, one size fits all, it is pot luck in a lot of cases.

    Whatever we take it always has to be gradually increased and blood tests are only guides. It is how we feel that is the priority.

  • Hi Nessiam,

    I do hope this helps you get your life back x As the other members have said, t3 dosing is a very personal thing, it has a half life of only 3-4 hours, so you may need to dose throughout the day. For my daughter, she feels best splitting her dose and taking it every 3 hours, though many people take it every 5 hours. In terms of feeling the effects/noticing a difference, it can take 12 weeks to clear rt3 once you are off of all t4. However it is very important to address your adrenals and iron as low cortisol and/or low iron can hinder the process of feeling better. Cortisol carries t3 to the receptor sites so is absolutely critical in regaining optimum thyroid health. From my understanding taking t3 is a little different to the other thyroid hormones when taking your dose. If you take your t3 sublingually (let it dissolve under your tongue) then there are no withholding periods in regards to foods and supplements. Keep up your research too. I wish you well and hope you feel much better s very soon. :)

  • Thank you so much, you are so sweet and I really appreciate your response! So you're saying if I let it dissolve under my tongue instead of swallowing, then I can have food and other vitamins at the same time without it affecting the T3?

  • Yes, that is how my daughter takes hers. You may want to have a read about it at rt3-adrenals.org. My best wishes to you. :)

  • I remember asking Paul Robinson from rwt3.com about dosing under the tongue. If I remember correctly he said the molecules were too big to be absorbed that way. But hey if it works for you and your levels are good then that's fine :-)

  • The effect of one dose of T3 in our bodies lasts for between 1 and 3 days. This is a link which is self-explanatory.


  • I take my T3 in two doses which seems fine for me. Looking at the chart eljii provided by the link, seems to suggest 5 x dosing maintains a steady flow, but for me that would be pretty tiresome (avoiding meals, etc).

  • I too take mine in two doses. Think we have to work out what suits. I found multi dosing a problem fitting in with meals at irregular times.

  • I was originally prescribed 1 x 20 mcg tablet a day, which I took in the morning. I found that by early afternoon I was feeling really bad. After five years of asking, I was finally prescribed 3 x 20mcg tablets a day. I take one as soon as I wake up, 1 about 3.30pm and the last one last thing at night. I found all the peaks and troughs that I had with one dose a day stopped and I felt much better throughout the day.

    I experienced a tremendous boost in my health when I split the doses but it could have been down to the increase. I never forget to take any of my doses as I definitely run down as the time for the next dose approaches.

    Personally, I would never go back to taking all the tablets at once. I would definitely consider splitting the tablets into more doses but they are such small tablets to cut up.

    Good luck. I hope you feel better soon.

  • I believe the only things to keep away from T4 and T3 is IRON, ANTIBIOTICS and OESTROGEN.

    The swallow/under the tongue camps are split 50/50 as far as I can see.

    The biggest thing I would say is be patient! If you've only been on NDT for 3 weeks you need to keep on track and find your right dose. I'm on week 8 and I had a terrible bumpy ride for the first 3 weeks, I was advised to increase a little quicker than the STTM protocol of 10 days and go by symptoms. I just had bloods done Tues. My GP ordered everything she could, but rT3 simply doesn't come up on her screen so she couldn't order it. I paid for the test from Medichecks £79 but all the other checks from the GP saved me £250.

    Finally, I think that instead of switching to T3 only, it seems that most people have it added in. If your blood tests show you really can't convert then T3 might be the answer.

    Good luck with it (oh and just a last thought - do you take your iron with vitamin C? I read you should)

  • My endo told me a dose of T3 lasts about 6 hours in the body. You could split your dose if you are not cutting pills up, effectiveness could then be lost and crumbling could lose some strength. You would have to work in having your meals 3-4 hours before any T3 dose (could this be a problem?). If your doc has not suggested splitting dosages why do you think this would benefit you? I have had great success and tolerance with one dose a day and I have, funnily enough, just had my dose increased to twice a day by my endo with a view to 3 times a day in 6 months time and come off T4 altogether. Because T3 is already a converted hormone it needs to be treated carefully for full efficacy. If you do have any effects taking it it should be transient whilst your body gets used to it, just go easy on yourself and maybe gave a sit down if you feel a bit of a body rush young on.

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