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Thyroid UK
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Upping dose from 25mcg to 50mcg for anxiety and depression

I posted my mid trial results to the endo who said that the TSH was largely the same and T4 just a tiny bit higher and that in this case the thyroxin wasn't really having an effect I could if I wished up to 50mcg per day.

I'm in a quandry as to what to do. I have also recently (last 3 weeks) upped my mirtazapine to 30mg. Yes the anxiety and depression have lifted somewhat but not cleared. It's hard to tell if the mirtazapine is perhaps not suitable for me or if I'm kinda under medicated on the 25mcg of thyroxine.

7 Replies

You are extremely underdosed if you are taking only 25mcg of levothyroxine. 50mcg is usually the starting dose with an increase around 6 weeks later.

An average dose is around 100mcg to 150mcg but it can obviously vary. Some take higher doses.

This is an excerpt re being kept on 50mcg and go to the date November 28, 2003 to read the whole question/answer:

Moreover, the dose he prescribed, 0.05 mg, is extremely small. It’s so extremely small that it's highly unlikely you'll benefit from it in any way no matter how long you take it. On the other hand, that small a dose may actually slow your metabolism more and worsen your symptoms. Perhaps this has happened, in that you say your symptoms have worsened since you started taking Synthroid.

It’s tragic that millions of patients such as yourself suffer needlessly for years because their doctors prescribe extremely small doses of T4 products. I advise all patients such as you to persuade their doctors to prescribe a product that contains both T4 and T3, such as Armour or Thyrolar. I also advise them to see to it—one way or another—that they take a high enough dose for it to be effective. Otherwise, the patients are almost certain to continue suffering.


Both anxiety and depression are also clinical symptoms of hypothyroidism and our brains require the most T3 (the active hormone) and some psychiatrists do prescibe liothyronine (T3) for depression. In T4 (levothyroxine) we have to have sufficient in order for it to convert to T3 to saturate all of our receptor cells of which there are millions.

I hope you feel better soon.

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Halinka, without seeing your results it's impossible to tell whether or not you need a dose increase. Your endo obviously thinks you do, so why not try 50mcg? If you feel overmedicated reduce to 25mcg/50mcg alternate days or go back to 25mcg.

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Hey Clutter, Thanks for your response. My start TSH was 1.79 and now its 2.11 and my T4 has gone from 9.6 to 11.2. He said because of the slight increase in the TSH 'if you are feeling tired, I could justify an increase in thyroxine from 25 to 50mcg. You may remember (I posted about this) that I had my blood test in the afternoon after having taken my thyroxine in the morning. Thanks, Kathy


Kathy, if you hadn't taken Levothyroxine and you had the test early in the morning TSH would have been higher. FT4 11.2 is low in most ranges (yours may be different) so increasing to 50mcg will be beneficial.


With such a low dose, your TSH response to the Thyroxine will be wiped out hence you will be back to square one before taking meds, so you should have your thyroxine increased.


Any anti -depressant negates the effect of thyroxine. Depression is a symptom of under active thyroid and when you are taking sufficient replacement it goes away. What have you got to lose? You can always go back if it doesn't work.

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Anxiety and depression don't go away that easily from medication

.Many A times it' is due to pschyosocial problems as well.Hormones can play a great deal too.Have a full hormonal blood count


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