Log in
Thyroid UK
91,917 members106,182 posts

What's the smallest dose of T3

I have been on T3 only for 12 days, after 'washing out' NDT for four days. My doctor recommended a start dose of 15 mcg a.m. and 10 mcg p.m. I can't get over 10 mcg (5 a.m. and 5 p.m) without going hyper - my heart feels it is beating too fast and I am feeling shaky. I woke up this morning feeling like that, so today I haven't taken anything so far. I have been treating high cortisol with ashwagandha for over a year. Apart from this, I actually feel much better: more energy, better brain function, happier mood. I know everyone is different, but has anyone started on a dose of 5 mcg per day without going even more hypo and then were able to increase the dose? I tried T3 last year, but it was a disaster because I started too high and still had loads of T4 and possibly RT3 at the time. NDT has improved things, but I have not achieved optimal health and am still very symptomatic.

22 Replies

I started on 1/8th of 25mcg tablet twice day, then after week increased to 1/4 tablet twice day (plus Levo)

After 6 weeks and blood tests results it was then increased by endo (changed to 20mcg tablets) in divided dose - 10mcg 6am, 5mcg noon and 6pm plus Levo at bedtime

You can cut tablets with sharp scalpel

Essential to have very good vitamin levels. Have you recently tested vitamin D, folate, ferritin and B12

Do you supplement, if so what with

Wow, just read your profile, even tougher time than myself.

Why do you want to try T3/T4 combo instead of NDT ?

1 like

Hi S, my Vit D was 25 (don't have ranges to hand as I am not at home at the mo), which was described as low. So I have been supplementing 8000 iu, per day since then, plus some K2. I have noticed pains in my hips and leg muscles but assumed this is low T4. Ferritin his high, but reducing. I take 1200 B12 sublingual methylcobalamin a day, vit c 1000 mgs, magnesium glycinate 800 mcg per day, a mineral multi, B2 B3, but no B5 (I looked at your profile - sounds like we have both been through the same ringer), CoQ10.I follow the AIP protocol and take 3 mls LDN, which is supposed to reduce cortisol and antibodies. My antibodies are over range and I have never managed to get /within range. I see a Functional Doctor who has always thought I should have a T3 only regime, so I am following her advice. I think I need more T3 than T4, which is why I want to introduce T3. As I said, I have noticed some improvements since stopping the NDT,which I assume is the T4 washing out.


Have you considered taking Vitamin B complex that includes all B vitamins


Your vitamin D was very low, assuming UK units. You can get pain as bones remineralise



The smallest Liothyronine tablet size is 5mcg. Boots supply either Perrigo or Sigmapharm 5mcg in bottles of 100 tablets (from the USA and expensive).

Your starting dose seems too high for Liothyronine, so this may be why you are not feeling right.

While 25mcg is the normal starting dose for Levothyroxine, it is not (or shouldn't be) the starting dose for Liothyronine.

I started with 5mcg and gradually increased in 5mcg steps over several months.

In my case, I was adding Liothyronine to Levothyroxine.

Once I was up to 20mgc Liothyronine per-day, I started to reduce my Levothyroxine.

It took me about 2 years to find doses of both Liothyronine and Levothyroxine before I was happy.

My current doses are 50mcg Levothyroxine and 25mcg Liothyronine, but please do not use this as an indication of what will work for you.

During my experimentation with doses, I also tried splitting the Liothyronine into twice per-day and I found this less effective than taking a single dose. Others prefer split doses, so there is no one-size-fits-all solution.

I have read that the cortisol level needs to be resolved before taking Liothyronine - high cortisol blocking the absorption/uptake of T3 (Liothyronine). So, it would be wise to seek help to resolve the cortisol issue before going any further with Liothyronine.

By the way, cutting Liothyronine tablets is not generally a good idea. Liothyronine is sensitive to humidity and high temperature (as is Levothyroxine, by the way). Good quality Liothyronine tablets are supplied either in blister packs (moisture protected) or in bottles with moisture absorber (the Mercury Pharma Liothyronine did not have a moisture absorber, which probably explains their short use-by dates).

Anyway, cutting a tablet means that the outer coating is no longer protecting the tablet from moisture at the cut point. If the cut tablet can be returned to a moisture-free environment (with a moisture absorber), then it may be OK for a short period.

From what I read (a while ago now), moisture (and/or high temperature) causes the active ingredient (e.g. Liothyronine) to gradually reduce in level.


Interesting about the damp getting into Lio tabs. I have been cutting up a few at a time and storing them in a box. Teva gives very detailed instructions on how to mix the tablets with water and then taking whatever proportion of the solution you need for your dose and discard the rest. Adding Lithyronine to Levo means you have some back-up, doesn't it? I feel I haven't got that at the moment.


Morningside Healthcare give same ridiculous advice that if taking less than 20mcg in one go to dissolve in water and use a syringe to draw up required amount .....and throw the rest away!!!!

So instead on one pill a day you'd be using three a day.

So that would be £27 a day ....£9 a day is outrageous as it is

Perfectly possible to cut into 1/2 or 1/4. I just cut one pill at a time.

Morningside Healthcare tablets are at least blister packed, unlike Mercury Pharma just loose in a pot.

1 like

Teva's loose in a pot as well.

1 like

As yousurname said 5mcg tabs are available. Which can be cut into quarters. I’ve not tried these but you may be able to cut again to get 0.625. There was an American Endocrinologist who suggested starting on 1.25-3mcg (different pill sizes) there’s also liquid T3. If you’re having these symptoms, might I suggest tell him/her that you’d prefer a smaller intro dose and the reason. Most of us start on 5/6.25mcg by cutting pills for two weeks. Are your vitamins to quality and your T4 intake the best it can be?


I'm getting the T3 on the NHS, so I'll see if I can get smaller sizes or liquid. I've got a good supplement regime. I haven't taken any T4 for two weeks as my Functional Doctor wants me to wash it out and go 'T3 only'. I've sent her an email about not being able to increase the T3, but haven't had a reply yet.



Please be cautious. The issues some of us are having getting T3, I’d suggest take what they give you and cut up the pills. You wouldn’t want to get the dreaded letter and then be stuck without while you fight for it to be reinstated or have to source your own for that interim person.


Yes I know, it's like hens' teeth, getting T3 on the NHS. That's why I really want it to work and it's frustrating that I can only do tiny doses, as well as the T4 washing out.


1/8th tablet is doable.....though not guaranteed perfect size every time

I very very much doubt NHS will cough up for 5mcg tablets

Decent level of vitamin D and folate essential

Ferritin can be high due to Hashimoto's.

1 like


1 like

The crushing of a complete tablet and dissolving sounds like a reasonable way to take a reduced dose, but this is a different issue to moisture protection for storage.

The implication is that, regardless of whether you cut or crush, the remaining part of the tablet should be discarded, as it will lose its effectiveness once exposed to moisture in a glass of water for longer than 5 minutes or to humidity in the air.

Yes, the cost is outrageous, but using the remaining cut pieces is likely to result in a decreasing dose, which may be fine if the total dose that you are receiving is satisfactory.

Probably better to get 5mcg tablets (which I have on NHS prescription from Boots) for a consistent, reliable dose, because this eliminates any uncertainty of your real dose.


Thanks Y, do I need to go to Boots and ask for the 5 mcg tabs (my local pharmacy happens to be a Boots anyway), or do I need to speak to my G.P.? I've been cutting tablets up and swallowing them like that rather than dissolving them in water. It seems like the same process to the gut.

1 like

Just cut up definitely


Your GP will need to change your prescription to 5mcg tablets.

Cutting will never be precise, especially with a naturally crumbly tablet.

Dissolving and measuring will ensure that you take a precise dose.

The remaining parts after cutting will be exposed to the humidity in the air.

1 like


It is more usual to introduce T3 in low amounts & slowly so the body can acclimatise to it.

Why are you discontinuing NDT ? ? . In your profile (oct 2017) you state how well you are feeling on it.

Those who can't raise T3 fast enough to avoid hypothyroid symptoms usually have either an iron or cortisol issue.

Your ferratin levels are high but have you had a full iron panel ? ? ... Ferratin can be an inflammation marker & high due to inflammation & you state your thyroid antibodies are elevated. Iron behaves in mysterious ways & is vital for good thyroid hormone synthesis.

If your iron is fine, and as you are still washing T4 out of your system, your high cortisol levels may inhibiting the conversion of T4 into T3 (deiodinase enzyme Type 1) shunting the conversion of T4 towards production of the inactive reverse T3 (via the 5-deiodinase enzyme Type 3) which in turn imbalances the RT3:T3 ratio, which may perpetuate further production of RT3.

Also elevated cortisol may result in low DHEA which is a precursor to all of your major sex hormones: oestrogen, progesterone, and testosterone. Have you had these tested ? / ... you previously mention fertility drugs. Remember all hormones work together and an elevation/deficiency in one will have repercussions further up the line.

You also mention Vit D is low. You have elevated thyroid antibodies & Vitamin D plays an important role in balancing the immune system (TH1 cell-mediated and TH2 humora). It does this by influencing T-regulatory (TH-3) cells (which govern the expression and differentiation of TH1 and TH2 cells.) Vit D is absolutely vital.

And have you had folate tested ? ? Folate (B9) works with vitamin B12 to help create, develop and regenerate red blood cells and make the iron work properly.

It may be an iron, nutrient or cortisol problem that is making you intolerant to enough T3 to bring well being.

1 like

Hi Radd, I am discontinuing the NDT because I had a downturn in mid-October, with increasing CFS type symptoms and when NatureThroid supplies were low. I had three amalgam fillings removed in September, albeit conservatively, which may have contributed to the crash. My functional doctor thought it might be an opportunity to try the T3 only regime. I did feel slightly better for a few days last week, but have got worse since the T4 is reducing. She has always thought that I might do better on T3 only because I have 'CFS' and have had high RT3.

Iron panel was normal in September apart from the high ferritin, which has come down a bit since I started taking LDN in July, as did my antibodies. I haven't had my adrenal profile done recently (plan to do that after Christmas), but my cortisol has always been high on the three previous ones. I take Ashwaghanda, but think I might consider an alternative adaptogen. LDN is supposed to be good for reducing cortisol, as well. DHEA was low. I had sex hormones tested a few years ago and they were 'normal'. I need to revisit the results and get them retested. I was told I wasn't ovulating properly when I had fertility issues, but it was in the eighties, when I didn't ask doctors any probing questions. My functional doctor doesn't seem to think sex hormones are an issue. I need to ask her why, I guess. I've got high heavy metal toxicity, particularly mercury, which could be contributing to high ferritin - i.e. inflammation.

I am taking 8000 iu per day of vit d, plus some K2 at the moment and will test at the end of January. Althought my B12 looks in the upper range on test results, my doc thinks I might benefit from B12 injections and I can go and get them from her. I am not well enough attend her surgery for the instructions as yet.



It may not be enough just to have amalgam removed as mercury binds to other molecules (usually the good ones that we need for good thyroid hormone synthesis - such as zinc ) becoming deeply embedded in tissue & this needs removing too.

Our bodies should remove mercury efficiently (& other heavy metals) but many of us have impairments that will hinder this process. Glutathione is the main detoxification system, together with enzymes, antioxidants, and transport proteins that get the conjugated mercury out of your cells and into the blood, as well as from your blood into your liver and small intestine, and into other places so it can be eliminated.

Toxicity is not just about the amount we have in our bodies but also our bodies response to the toxicity which depends on the strength of our detoxification system.

I had mercury poisoning too & had all amalgam removed. Are you chelating ? ? .. Chelation protocol is scientific using sups known to detoxify by transporting the toxic metals from inside the cells, to be bound and eliminated in urine & faeces so avoiding reabsorption. Also to replace nutrients and and protect against the damage done by DMSA, etc.

If you click on the green reply button, the person is notified. I only saw your reply because another member “liked” my previous answer to your post.




Hi Radd, I am not chelating yet because I have six more to go. I am following the Andy Cutler protocol and am taking the '4 core' - zinc, vit c, magnesium and coq10. I am also taking liposomal glutathione. Once I have had the rest of the amalgams removed, when I am well enough that is, I will start the chelation process. The Cote Royd Clinic in Huddersfield has been recommended.

P.S. I am up to 15 mcg T3 a day in four divided doses and starting to notice an improvement. Thanks for your advice.

1 like

Radd, this has been playing on my mind. I realised that the AC protocol for the 4 core does not include CoQ10, but vitamin E. Thought I'd clear that up!


You may also like...