Why do I have palpitations on low dose thyroxine

Was diagnosed with Hashimoto's 3 weeks ago based on raised anti-bodies and family history of it. TSH, T4 and 3 in range tho latter two on the low side. Cos of symptoms of depression, endo put me on low dose thyroxine, just 25mg. I also take low dose mitarzapine (an anti-depressant). I'm three weeks in and starting to feel quite anxious and having mild palpitations. Not sure what to do? What is it about taking thyroxine that causes these palpitations? Is it unsafe to plough on with it, or should we treat the palpitations as a warning. H

35 Replies

Halinka, it may be the palpitations are due to low thyroid hormone and it is coincidental they started after you began taking Levothyroxine. Sometimes the change in hormone levels can cause palpitations temporarily. Occasionally Levothyroxine will cause palpitations. When you get your next prescription ask the pharmacist to give you an alternative make. Mercury Pharma and Wockhardt both do 25mcg. Sometimes a change of make can make a difference.

Palpitations are unpleasant and alarming but not usually damaging in any way.

Clutter, Thanks for the quick response. When you say low thyroid hormone, would that be T4? MY T4 and 3 were both just in range/ on th slow side. I'm on levothyroxine. I really wanted to go on NDT as it includes T3 which I read helped augment antidepressants. But the endo wanted me on Levo initially. Are palpitations less likely with NDT/ Armor?


There are people who prefer NDT as it includes all hormones as you rightly say but unfortunately it is not licensed in the UK so is very difficult to get on prescription.

As advised on ThyroidUK website there is a small possibility of getting it prescribed on a "named patient" basis by an endocrinologist but this is unusual as most doctors and endos will want to prescribe Levothyroxine.

It is still early days Halinka and your hormone levels could take another few weeks to level. Levothyroxine takes 6 weeks to initially saturate every cell meaning 6 weeks until you feel the full benefit.

Your doctor should retest after 6 weeks and adjust dose accordingly and hopefully palpitations should have righted themselves by then.


Thanks Flower. Endo asked me back in October but as you say, I think a half way point review might make more sense. He also suggested a B12 test in Oct but again, I'd rather get one done sooner.


i see nothing about all hormones, only t4 and t3.

Armour is a brand name for Natural Dessicated Thyroid. This is made from dried pigs thyroid gland believed to offer all hormones in as close a proportion as possible to that of a humans requirements. (Although I read in that report I recently posted that the proprtions are actually quite different.)

T1 and T2 aren't usually mentioned as the amount is so minute.


It was never as STTM kept saying..even the Calcitonin is too low to mention, not enough for helping bones. T2 and T1 come from the metabolism of t3, in the body organs like the Liver and Gut, not thyroid gland. If NDT had all these wonderful hormones contained, the manufactores would be advertising it all over the place!!! It just isn't so, unfortunately. On the other hand, it sure can provoke a Hashi's attack. I had never been so ill, as i was when on it. Erfa and Armour tried it 3 times. It took 8 months after stopping for the hyper symptoms to stop.

That's terrible faith63.

We just never know how we are going to react until it is sometimes too late. I haven't tried NDT but have had my share of unwanted reactions with the glandulars.

There seems to be conflicting views on Hashi suffers taking NDT with some believing adding gland tissue encourages more antibodies as they attack.

The other side of the argument is as written in STTM............

Some doctors will state that those with Hashimoto’s should avoid NDT because it can increase the attack. It’s true that at first, antibodies raise, say patients. But the higher they raise, the lower antibodies become, as reported by many, probably due to a better immune system due to the T3! A large body of Hashi’s patients need to avoid gluten to get those antibodies down. Others use 200 – 400 mcg selenium to lower antibodies, while more difficult cases may need Low Dose Naltrexone. Many even report that their iodine use lowered their antibodies.Overall, Hashi’s patients have soared with NDT if they do it right,



Very familiar with STTM and that explanation. If i had continued to raise, i would be dead now. My resting heart rate went into the 100's, on less than 2 grains..some labs showed all over range..i had indeed gone hyper, from another Hashi's attack.. i could not raise. GF didn't help me one bit. Did you know you can get 0 antibodies..when your immune system become too weak to make them? Not mentioned and not a good thing. My dependance on STTM is what caused me to believe that without ndt, i would never feel well..so i poisoned my self 3x. I no longer read that site. My friend spoke to Mary Shoman, who has many clients coming from STTM, who have become very ill by following their guideleines.

My spell check is out!!! Excuse this mess!!! Too tired to fix it all.

Thank goodness you came out the other side faith.

I know T3 isn't your answer and so it must be difficult to know where to go now.

Do you have any ideas or just hoping raising the usual cortisol, iron, etc will help?

Feeling so bad for you, flower007

I am going to go to integrative medicine doctor, where i am sure they will test for Virus's, bacteria, minerals etc, maybe recommend a regamine of steroids, that don't cause me to swell worse, which is what i don't understand..low cortisol but high blood sugar and normal bp..makes no sense. My hope is they will find a reason why i have, what appears to be, chronic inflammation, pain and swelling..a constant flare of autoimmune issues. Why my diet doesn't work, since i eliminated all i am sensitive to, according to testing..so must be something else going on? Who know's. I will go to a Neurologist to see why a SPECT Scan showed low brain blood flow and what to do about it, also get a diagnosis for fibromyalgia and chronic fatigue syndrome, just so i can get some kind of disability [which i know my pain and fatigue is not a separate condition] My hope is to feel well enough to travel to Boston to the Pituitary Center in the Fall.

Thanks for all of your kindness. We have both been thru too much.

Oh faith, I am so glad you have a plan because looking towards a positive future is important for our healing.


Thank you. Sometimes i don't feel so positive and get very depressed.

Halinka, High dose Levothyroxine and high dose Liothyronine have been used to treat euthyroid and hypothyroid patients with anti-depressant refractory depression by psychiatrists. Endocrinologists are against this. Increasing low hormone (FT4 and FT3) with Levothyroxine can improve low mood and depression but I'd be surprised if 25mcg is very helpful.

Palpitations are no more or less likely on NDT unless the palpitations are caused by one of the fillers in Levothyroxine. NDT is rarely prescribed on NHS. Most people buy theirs online.

I am euthyroid. It's just my antibodies that are out. Why are ends against using T3 for depression?

Halinka, endos treat hormonal imbalances. If thyroid levels are within range they don't want patients given thyroid hormone as there may be knock on effects on bone and heart health (I'm not suggesting 25mcg will cause this).

If you want hormone treatment for depression you need to find a psychiatrist who uses that protocol. I don't know how commonly it is used in the UK. Research I've read discusses supraphysiologcal doses of Liothyronine or Levothyroxine (400-500mcg Levothyroxine is discussed below) for anti-depressant refractory depression.


Thanks Clutter. I have read a number of reports suggesting T3 was used in the past. Finding a psychiatrist who will prescribe T4 or 3 is gonna be a challenge. I might see what a second visit to the endo might reveal. He certainly seemed ok about using armour which would give me my T3. Thank you. No palps today at all which is nice :-)

Halinka, you can buy T3 and NDT without prescription online but advice on dosing will be for thyroid levels rather than for relieving depression. Of course, if your depression is due to low thyroid then T3 or T4 will help.

Clutter, I'm pretty sure my low mood is caused by factors other than my Hashimoto's but I went to the endo as I believed it could be contributing to it. Do you think the 25mcg could actually be unhelpful? What I'd love to do is try NDT cos of the T3 in it. But I guess I need to wait a little longer. I did read one report about research into my antidepressant - Mirtazapine and thyroxine which if understood it correctly, implied that the Mirt. helped with conversion of T4 to T3. Hmmmmm. Halinka

Hi honey.

I will tell you now mirtazapine causes palps. I'm hypo thyroid and I suffer with depression and anxiety.

I was on 30mg of mirtazapine for 3 years. And had constant palpitations, I even see a heart specialist and my heart was fine. Basically I would lay in bed and it would be like boom boom pause big boom. Or it would skip every other beat, when I finally weened off of the mirtazapine they slowly went away and completely disappeared when I was off of it.

Although it really helped me sleep and helped my anxiety

Maybe ween off of it and try a new one. But I will say being under active can cause depression anyway. You may just need a increase in levo and a bit of therapy. That's the road I'm on anyway.




Thanks for your response. Been on Mirt for 8 months without any palps and can't really wean off yet as still very low. You say you are hypo. Is it Hashimotos? Were you TSH, T4 and 3 levels out before you started on Levo? Halinka x

No I'm not Hashimotos, I went hypo when I was pregnant with my little girl and I've been over and under since. My last blood test I had a TSH of 29 and a t4 of 9 so I'm on 75mcg of levo xx

Hi Early days as takes a while to work. Normally my heart is worse if dose to high or to low.


Thanks Jackie. I think they way I'm gonna deal with it is to bring forward a blood test. 3 months before testing is a long time.

My Own Experience: - 25mcg is a very low (tiny) dose, and whilst it may show an initial effect (good or bad), it's unlikely to maintain effectiveness past 4-6 weeks, as the HPT feedback loop will compensate for this low dose and reduce the body's own T4 production accordingly, so you’re generally no better off. Look at the newer guidelines for starting dose of T4 (Thyroxine) - it's generally 100mcg for anyone under 50 with no heart problems. Anything less will "Usually" cause the up-down effect as quoted by Dr. Myhill (made popular by Dr. Kenneth Blanchard). My own experience was a couple of hand-wringing GP's who were scared to death of increasing my dose above 25mcg despite Dr. M asking them to. Eventually I got onto 100mcg and finally started to feel better. This took me 18 months when in reality I should have been put straight on to 100mcg. My Palp's have now reduced as my dosage increased! There are still unknown reasons why some of us don't produce enough T4 (or T3), and need the help of medications to boost our levels. I think there is something "blocking" the feedback system somewhere, as the useless TSH, T4 & T3 can all be in range, but are far from ideal for some of us.


Where might I find these newer guidelines? Is that where I'll find Dr. Myhill comments about the up and down effect?

I don't think my endo wanted me on a higher dose as I'm euthyroid. Hashimoto's is big in our family though and so he was happy to 'trial' 25mcg thyroxine.

My last labs:

TSH 2.226 (0.35-4.94)

Free T3 2.59 (1.71-3.71)

Free T4 0.81 (0.7-1.48)

Anti TG 40.33 (<4.5)

Anti TPG 55.26 (<6)

I'm not sure what to think now.

Hi Halinka, sorry for the delay.

Latest BNF Guidelines: - "ADULT over 18 years, initially 50–100 micrograms once daily, preferably taken at least 30 minutes before breakfast, caffeine-containing liquids (e.g. coffee, tea), or other medication, adjusted in steps of 25–50 micrograms every 3–4 weeks according to response (usual maintenance dose 100–200 micrograms once daily); in cardiac disease, severe hypothyroidism, and patients over 50 years, initially 25 micrograms once daily, adjusted in steps of 25 micrograms every 4 weeks according to response (usual maintenance dose 50–200 micrograms once daily);

See full page here: - evidence.nhs.uk/formulary/b...

The "Up-Down Effect" is originally quoted and observed by Dr. Kenneth Blanchard who has an excellent book on the functioinal approach to treating Hypothyroidism. Dr. Myhill quotes his observations, including this up-down effect. I have personally had this symptom with under prescribing by my hopeless hand-wringing GP's, and it took Dr. Myhill to make them realise they were wrong!.

Also Dr. M has her own evaluation / prescribing guidelines : - drmyhill.co.uk/drmyhill/ima...

Dr. A. Toft is also referred to by Dr. M, and he again prefers a similar approach to give sufficient medication to move the T4 & T3 to the upper parts of their ranges (sometimes above range for T4). All these "Knowlegeable Doctors" agree that the TSH can be very misleading and dosing according to TSH is NOT satisfactory!

Please understand I'm no expert, I'm only going off personal experience here. My own opinion is that your results above most definitely warrant a decent trial / increase of Thyroid medication. Others on here are much more knowledgeable than I am on prescribing, and would be better able to advise on that.

Apologies for the long reply.

Good luck - I hope you find a good Doctor who will help you get better!

Low doses of Thyroid Hormone will actually be too low, making Hypo symptoms worse. Levo is not used for depression, but t3, Cytomel is. You will need testing of ft4 and ft3 to get a better picture, but 25mcgs is even too low for a baby.

ndt, contains both t3 and t4..no mentionm of other hormones being in it.

You need full thyroid hormone replacement when symptomatic, with Hashimoto and .treatment can stop the attack and lower antibodies. You would be wise to find a new doctor because this one will leave you ill, i fear. Apparently doesn't know how to do thyroid hormone replacement. Hashimotos in itself causes depression and anxiety, pals all sorts of terrible symptoms. Your doctor is not aware, as most are not.


Great link faith63,

Thank you for posting.

Just proves the importance of reducing antibodies and what far reaching effects Hashimotos really has, whether directly or indirectly, the results are still the same.


Thanks..those symptoms are me and i am getting worse..so much pain. I thought that by taking t3 only, i could bypass my reverse t3 issues, but the body will find another way to keep the metabolism low, if that is what it is trying to do. I need to keep looking for answers.


I do have Hashimoto's but its only reflected in raised antibodies. All my other results are in range:

TSH 2.226 (0.35-4.94)

Free T3 2.59 (1.71-3.71)

Free T4 0.81 (0.7-1.48)

Anti TG 40.33 (<4.5)

Anti TPG 55.26 (<6)

I think that is why I've been started on a low dose.


Your labs are low. You need to continue to raise until you are at a full replacement dose and feeling better...raising every 2 weeks or so, to lower andtibodies. If your doctor is not aggressively raising, and testing within 4 weeks, he doesn't know how to treat. Also you need to start researching about possible causes as to why your immune system has gotten bad. Food sensitivities and allergies, virus's etc..


With regard to your results, I agree with faith63 about needing an increase in Thyroxine to help manage Hashimotos. More thyroxine will eventually suppress the TSH level (below range) and stop stimulation of the thyroid gland which should help to reduce antibodies. Hashi attacks encourage TSH levels to fluctuate and can make you feel very unwell with swings between both hyper and hypo symptoms.

However, you have only just started medicating on thyroxine and the body can only tolerate small increments at a time.

Six weeks after initially starting thyroxine, your doctor should retest your thyroid hormones and adjust dose accordingly. This is when it gets tricky because most doctors like to keep us "in range" because they don't understand the full implications of Hashimotos and may be reluctant to increase your dose.

When you are blood tested, get the earliest appointment, fast and don't take your pill until afterwards. This will ensure you get the highest possible reading of TSH levels and so are more likely to be prescribed with a med increase.


25mcg is just a starting dose but enough for the pituitary loop to recognise & adjust its signal to stop telling your Thyroid to produce hormone (if it was still producing).

Oh diagnosis (in UK) you receive an NHS exemption payment card - hormone for life - why's that do you think?

I felt much worse to start with on Levo, but had read up and expected this.

It will get better (I keep telling myself!) J :D

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