Feeling worse on Levothyroxine/Euthyrox - Thyroid UK

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Feeling worse on Levothyroxine/Euthyrox



I took Euthyrox a few years ago (25mcg/day) but didn't felt any difference, so I stopped taking it.

My thyroid lab results never looked any good, that's why I decided to start taking Euthyrox again. My doc told me to take 25mcg/day and maybe (!) increase after a while.

I started taking 25mcg Euthyrox 10 days ago. The first few days everything was fine (not feeling better, but also not feeling worse), but now I feel veeeeery tired and sluggish and want to sleep all day. I don't have the power to do things. I feel so much worse than before taking Euthyrox.

Should I increase to 50mcg? Is it harmful to take 50mcg for a few days to see how I feel and then go back to 25mcg if I feel worse on 50mcg?

Unfortunately, I don't have any lab results right now. All I know is that my TSH was 5.94 μIU/ml [0.40 - 4.00] 1 year ago.

I take the tablet in the morning on an empty stomach.

I am 195cm tall and weigh about 100kg (gained 20kg in the last 2 years). I am a 24-year-old guy.

I tried NDT about 2-3 years ago but it made me feel like I'm almost dying.


10 Replies

25 mcg is a starting dose in elderly people and those with heart disease. A usual starting dose in young, healthy people is 50 mcg, and then you raise the dosage every 6-8 weeks until you feel optimally treated.

It's recommended - and I have found this to work best for me - to take your body weight and then multiply it by 1.5 to calculate your maintenance dose of T4.

Just remember one size does not fit all. Some people need enough T4 to slightly suppress their TSH and/or raise their free T3 levels. Of course, this requires you to be able to convert enough T4 to the more active hormone T3. There is no way of knowing that until you take enough enough T4 (I'd expect you to need at least 150 mcg daily, possibly more).

I am not surprised you felt bad on 25 mcg of Euthyrox as that is only about half the starting dose for a young, healthy individual...!

in reply to Hidden

Also, NDT does not fit all. I have gone off it recently and back on T4 only and so far feel better.

It's not a good idea to take a given dose of T4 for a few days and then go back to your previous, lower dose. FT4 levels will build up slowly over several weeks (T4 has a half-life of about one week) so you need to stay on any given dose for at least 6-8 weeks to be able to tell if it's too high or low for you.


It takes 6-8 weeks for each dose of Levothyroxine to balance

The standard starter dose of Levothyroxine is 50mcg.

The aim of Levothyroxine is to increase the dose slowly in 25mcg steps upwards. Retesting bloods 6-8 weeks later after each dose increase. This continues until TSH is under 2 and FT4 in top third of range and FT3 at least half way in range

For full Thyroid evaluation you need TSH, FT4 and FT3 plus both TPO and TG thyroid antibodies tested. Also extremely important to test vitamin D, folate, ferritin and B12

Low vitamin levels are extremely common, especially if Thyroid antibodies are raised

Recommended on here that all thyroid blood tests should ideally be done as early as possible in morning and fasting. Last Levothyroxine dose should be 24 hours prior to test, (taking delayed dose immediately after blood draw). This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip, best not mentioned to GP or phlebotomist)

List of hypothyroid symptoms


NHS guidelines including what foods to avoid (note recommended to avoid calcium rich foods at least four hours away from Levo)


in reply to SlowDragon

Ok, I'll update my posts so they say every 6-8 weeks instead of every 4-6 weeks.


25mcg is an incremental dose unless someone is very frail with a heart disease.

Usual starting dose is 50mcg, with a blood test every six weeks with a 25mcg increase until the TSH is 1 or lower and a Free T4 and Free T3 in the upper part of the ranges. The latter two are rarely tested in the NHS. There are private labs that will do the 'frees' and they are home pin-prick blood draw which you post and then get the results from the labs.


Update: I found this article where it's suggested the maintenance dose of T4 should be 1.6-1.7 mcg per kilogram of body weight, possibly even as much as 2.1mcg x kgs of body weight.


in reply to Hidden

in the patient information leaflet of the Euthyrox I am using it says 2-2.5 mcg/kgs body weight as maintainance dose...

in reply to rumpelstilzchen

Yes, this is not exact science...but you should always feel well and have no remaining hypo symptoms when optimally treated. Many doctors keep patients on too low a dose because they think a TSH "anywhere in range" is enough.

So, I upped my dose from 25mcg to 50mcg and I am currently at 75mg.

My lab results on 50mcg:

TSH 2.98 μUI/ml [0.4 - 4.0]

fT4 15.20 pg/ml [9.00 - 17.00]

fT3 4.17 pg/ml [2.20 - 4.40]

TPO - Antibodies 16.1 lU/ml [< 34 negative]

TG - Antibodies <10 lU/ml [< 115 negative]

Anti TSH-Receptor Auto-Antibodies < 0.8 IU/l [< 1.75 negative] [>= 1.75 positive]

My lab results on 75mcg:

THS 0.65 μUI/ml [0.4 - 4.0]

fT4 13.40 pg/ml [9.00 - 17.00]

fT3 4.00 pg/ml [2.20 - 4.40]

I am not sure if I should keep raising my dose as you guys told me (and like it says in the patient information leaflet) or if I should stay at 75mcg or if I should decrease my dose back to 50mcg?

I am not feeling any better nor worse on my current dose but I felt pretty bad and weak when I switched from 25mcg to 50mcg. Well okay, I would say that I am feeling sliiiightly more energetic at 75mcg than before Euthyrox.


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