Some advice on changing from T4 to T3 please - Thyroid UK

Thyroid UK
109,941 members127,795 posts

Some advice on changing from T4 to T3 please


Hello, I had a recent visit to an Endo and she told me that I’m allergic to T4, it’s only taken 15 years and the destruction of my mental/physical health not to mention the complete destruction of my career to discover this, how we laughed!! anyway she is going to get my GP to prescribe T3, so far so good, this was a couple of weeks ago, so I booked an appointment with the GP and turned up last night expecting/hoping to get a prescription however he hasn’t received her letter yet so understandably didn’t want to give me a prescription, he says he’s not even sure how to prescribe it as he’s never done it before! I think she may be waiting for results of bloods taken at GP’s last Thursday as she’s testing for Addison’s, who knows, anyway while all this was going on I thought s%d it I’m going to order T3 (Uni Pharma) so I’ve got a fall back position should the CCG or GP decide that they aren’t going to give me T3. My question is what sort of T3 is offered on the NHS, I know they only do one brand hence the exorbitant, totally immoral cost, I think it’s Mercury Pharma? The T3 I’ve ordered hasn’t arrived yet and I know it can take a couple of weeks, but it has been posted to me. my question is if it arrives before I get an NHS prescription should I go ahead and start to take it or should I wait and see if I get it on the NHS, what I don’t want to do is start taking different brands and chopping and changing if that’s going to mess the transition up. I will be starting on a really low dose 10 Mcg so perhaps that would mitigate any change in potency? Also should I just stop taking T4 or reduce it gradually not that I’m taking much at the moment only 25 Mcg as any more makes me ill. I should be on 100, 125 alternate days. Also when increasing T3 what should the amount and time periods be? Many thanks for any thoughts on the above.

14 Replies

Hi-just replying to give moral support,others will follow with the information you need.

I was on thyroxine for 16 years,culminating in 2 years depression with acute anxiety states,with constant suicidal thoughts,followed by 2 years chronic profound fatigue.Moving from Wales to Cumbria,my new GP sent my results to the endo,who could see I wasn't converting well.She wanted me to take T4 & T3,but I gave up T4 & have been on T3 only for over a year,with huge benefit.I have relapsed into anxiety with depression,following trying to add some NDT,but hope to get through this now I am back on T3 only.

I have now been told I will not be supplied T3 by the NHS,though I am waiting for an appointment after blood tests to see if she is willing/able to allow me to continue with NHS Mercury Pharma.I have been buying my own Greek Unipharma to top up & it looks like I will now be paying for the whole of my daily dose.

From this forum,I understand she may be able to provide me with a private prescription for French or German T3,which would cost me £300 per annum,as an option.

I wish you good health.This forum has saved my life

Marty123 in reply to Naomi8

Well you succeeded in making a grown man cry, I won’t lie it’s been a hard 15 years and when I hear that someone else, lots of people judging by this forum, have been in the same boat it makes me weep. I’m about at the end of my tether, left work last week as I just couldn’t cope anymore. I’m really hoping that T3 works for me, please god!! Thank you for your kind words but to anyone else who wants to be nice to me, don’t it makes me cry!!

Hi what where your symptoms of being allergic to thyroxine please. it's awfull having to wait so long to find that out x

Main symptoms anxiety, no confidence, this from the most confident person on the planet! Mood swings, sleeplessness, sudden fatigue, I mean looking at shop doorways thinking, that looks cosy, But the most awful one was as Naom18 says suicidal thoughts honestly thought they were going to have to lock me up this went on for two years!!!! Within 2 weeks of stopping taking Thyroxine I was back to normal unfortunately my TSH was 69.7 but I felt better than I had in years. GP insisted I take some T4 so am taking 25 Mcg but want to stop it asap.


My GP has been told by some official body or other that he is not allowed to continue prescribing me with T3 it is a hospital only drug despite the fact that my endo asked him to over a year ago (admittedly he has been upping my dose). He wrote to the hospital requesting permission to continue prescribing it but has not heard back as yet (two months) however, he will continue to prescribe 3 weeks at a time until he hears from them and has promised me he will sort it out.

My answer to your question is, yes, if you want to take the T3 you have ordered before getting yours on NHS, go ahead, I have used Tiromel and UniPharma T3 when running low on my prescribed T3 and I haven't noticed anything different. I will say, that since starting T3 I have never felt better.


I think the only risk with starting self medicating is if they then want to run other tests. You would have to wait a week for all the T3 to be out of your system before going for the test.

Marty123 in reply to Ruthi

will keep this in mind thank you.


If you are supposed to be taking 100/125mcg Levothyroxine but unable to tolerate it you should be prescribed an equivalent dose of T3 which is 33-40mcg. It is usual to take T3 3 x daily to even out the T3 peaks in the blood.

A lot of people will tell you how they increased gradually from 5mcg over months but I was prescribed 60mcg immediately after thyroidectomy and switched between Levothyroxine and T3 without tapering when I required RAI.

Marty123 in reply to Clutter

thanks for info will keep in mind, GP has no idea but he is supportive just keeping fingers crossed and hoping for the best.

Clutter in reply to Marty123


10mcg T3 is equivalent to 30mcg Levothyroxine. If your GP thinks you need 100/125mcg Levothyroxine he should prescribe 30-40mcg T3.

T3sortedme in reply to Clutter

Taking T3 in 3 doses across the day is important. The first dose is the largest and the second two 'topping up' for me. I take 20mcg at 6.45am (wake up time), 10mcg at 12.00 and 10mcg at 5pm. It means empty stomach which is ideal and convenient times. I set an alarm on my phone which rings even when set on silent. Missing or late dose can empty me of energy for the rest of the day. Discipline is very important (30 mins late for a dose is max tolerance for me).

We are all different, but that is what I have found works well for me.


It's such a sad day, in a way, when it is finally discovered that a patient's health has been destroyed due to the inability of doctors to use their common sense when a patient isn't improving.

There have been studies that levothyroxine isn't the best for many people and it has had more recalls than any other thyroid hormones, I believe. Also they are given more medications for their remaining symptoms and not hormones.

People are having lives of illhealth brought about by the Medical Profession's insistence to go only by the TSH.

10mcg of T3 is around 30mcg of levo which might be too small a dose if you've already been on levo.

I hope you get to an optimum dose quickly and that they wont stop due to the TSH but concentrate on relief of your symptoms.

When I switched from T4 to T3,I had to reduce my T4 from 125mcgs.If you are only on 25mcgs T4,it could well be a smoother quicker transition for you.I would still recommend starting with 5mcgs 3 times a day at first,as I think our bodies have been starved of T3 if we cannot convert,but hopefully you will be able to increase without the reaction I had.

I started with 5mcgs T3 three times a day,while reducing T4,but had a big reaction( tachycardia)which took me to A&E then overnight in hospital,for observation(to rule out AF)

I started to improve after I got all the T4 out of my system,reducing thyroxine as quick as I could.

I now take 55mcgs in 2 doses,30mcgs at 6am & 25mcgs @ 6pm.Some people take 3 doses a day,some take it all in one.

I found Paul Robinson's books very helpful.DR JC Lowe is a fount of wisdom.Shaws posts many heplful sections from his archives & it always gives me courage to read them.

Marty123 in reply to Naomi8

OMG i shall tread with care thank you for your info.

You may also like...