Thyroid UK

Synthroid (Levo) causes anxiety?

Hi all,

A few weeks ago, my doc prescribed me a different brand of levo I believe, and the color of the pills were pink (112mg), and since taking them I have constant panic attacks and random episodes of anxiety. I have had anxiety before with certain dosages but never this dose; I have also never taken this color pill. I emailed my doctor and he said I could be allergic to the color coating and that may be whats triggering these racing thoughts and panic attacks. However, I can't get the dosages changed for a few more weeks.. What can I do? And is this normal side-effect?

6 Replies

You need to look up the brand and find the expedients (non active ingredients). Many of the brands contain acacia and povidone both of which I have trouble with as they can be histamine liberators in some people. Colouring is also likely to be a problem. Generally I react to artificial colours such as azo dyes but am ok with stable ones such as red iron oxide. They tend to colour different strengths in order to make it easier to tell which you are taking but some people here in the uk just use the white ones and make their dosage up with several of the white ones rather than risk the colour. Perhaps this is something you can do. It can also take a few weeks to settle down on a change of dosage and you may find you can just ride it out until you get the prescription changed. You can also try just washing off the coating in the meantime to see if this helps a bit. Good luck


Also, do you know your ferritin level? Low iron can trigger panic and anxiety. The change to the pill could be a coincidence, not the cause.



I think you'll find the word is "excipients" - you can thank your spelling checker for messing that up. :-)

The people in the UK don't use white ones in order to avoid the risk of any colouring agents. All UK levothyroxine and liothyronine tablets simply are white. No need to do anything to avoid colours. (A few people from elsewhere on the planet have coloured tablets.)

UK people also very often have to make up their dosage from several tablets simply because we only have 25, 50 and 100 microgram tablets.

I could well be wrong here, but all the coloured levothyroxine tablets I have seen are coloured right through. It isn't a coating. Even if it were a coating, I really don't think washing it off is a good approach. No telling how much active ingredient you get rid of.


I can only tolerate Wockhardt in 25mcg tabs as they are white and no nasty fillers like acacia which caused anxiety and panic to me too. I can't take any coloured pills and react to chemicals in foods.

Endo instructed GP to prescribe them for me .


My full-replacement dose of T4 is ~130mcg (1.7mcg/kg body weight). I cannot take anywhere near 130mcg, approaching 100mcg I get terrible anxiety and generally hyper brain. I was on T3-only for over a year, and that worked well. I finally went back on T4 at just 75mcg daily, and filled in with T3 at 15mcg daily, to get my TSH down to 0.5 and my FT3 up to mid-range. Voila, works perfectly.

Making the assumption that the T3 power factor is between 3 and 4, this puts my T4-equivalent dose between 120 and 135 mcg daily.


I wonder if you are just absorbing this new brand differently.

When I take almus/ activis or workhardt it hits my system like a train. Horrible. Anxiety and panic!

I've stuck to Mercury Pharmacy for that reason. I suspect it is either weaker or is absorbed much slower. Either way it suits me better.

I wonder if you could change back to your original brand?


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