Thyroid UK
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Levothyroxine Side Effects

I began treatment for hypothyroidism with a prescription for Armour Thyroid. As I neared the end of the first 30 days I was informed by my health plan that Armour was not in their formulary so they would not pay for it. I then switched to levothyroxine, which is on the plan's formulary and within 3-4 days I began to experience severe muscle and joint pain to the point I was losing sleep, couldn't go to the gym, and was unable to work on my wife's "Honey Do" list. I discontinued the drug after 2 weeks...and after one week with no treatment have gone back to Armour (I'm paying for it myself). I'll let you know if being back on Armour helps me feel better.

2 Replies

Welcome to the forum, DavidMGus.

It's sometimes worth trying different brands of Levothyroxine as adverse effects are usually caused by a filler ingredient and different brands have different fillers.


I don't think its as much that you necessarily have side effects as that the two are different drugs.

Armour contains both T4 and T3, whereas Levothyroxine is T4 only, which you have to convert to T3 yourself. But conversion to T3 is a slow process and so when you first went on Levo your T3 levels will have dropped significantly. It takes two months for your T4 level, and therefore the amount of T3 that you are converting from it, to stabilise. If in addition to that you weren't on a high enough dose for your needs and conversion rate, you might have needed a dose increase to get to the T3 level you need. Without testing your free T3 you will never know.

But I do think you haven't given Levo anything like a good enough go to be sure that its not going to work for you. I imagine you will feel better pretty quickly back on Armour.

It is of course possible that you are not a 'good converter' in which case NDT or T3 only would be the only solution.

Armour is not the only NDT. There are cheaper versions available from Thailand, and it is possible to obtain them without a prescription if need be.


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