Brain fog and meds: Hi all. Would be interested... - Thyroid UK

Thyroid UK

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Brain fog and meds


Hi all. Would be interested to hear from anyone who is medicated for underactive thyroid but still suffering brain fog. I've had terrible problems for ages with all the different meds but eventually discovered if I don't eat gluten I can actually tolerate the meds. I feel better on ndt than levo but the brain fog is driving me crazy. I think on T3 only I had a clear head (although when I tried it I was still eating gluten and struggled to tolerate it at that point) but I'm hoping now I'm GF (non hashis and not celiac) I will tolerate it better. Just curious if anyone had a similar brain fog experience and whether they found T3 was the answer. Thanks all.

6 Replies

Thousands on here with Hashimoto's or Graves find strictly gluten free diet helps or is essential

Essential to get vitamin D,folate, B12 and ferritin tested and supplement to optimal levels too

Couldn't see any vitamin test results on previous posts.....when were these last tested ?

Add results and ranges if you have them, plus say what supplements you are taking

If not been tested, suggest you do full Thyroid and vitamin testing

Medichecks Thyroid plus ultra vitamin or Blue Horizon Thyroid plus eleven are the most popular choice. DIY finger prick test or option to pay extra for private blood draw. Both companies often have money off offers.

All thyroid tests should ideally be done as early as possible in morning and fasting. When on Levothyroxine, take last dose 24 hours prior to test, and take next dose straight after test. This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip, GP will be unaware)

If also on T3, or on NDT make sure to take last dose exactly 12 hours prior to blood test

Olsbird in reply to SlowDragon

Thanks. I haven't got recent tests but this brain fog issue has been going on for ages (when ferritin etc was ok). I know T3 shifts it but cannot understand why as ndt doesn't. Ndt of course has T3. I couldnt really get an answer from the endo so was curious whether it's just me. I'm not hashis graves or celiac so again bit unusual to have issues with gluten (which doc wasn't able to explain either why gluten intolerance would cause me issues with any thyroid meds. Round and round we go.....😩


When I was on Levothyroxine I still had brain fog, found it hard to concentrate and make sense of things. As soon as I stopped Levothyroxine and went on T3 only this lifted and I could think straight.

Unfortunately, I’m not doing well at all on T3 alone, so it’s a cause if going back to the drawing board.

Best Wishes


Olsbird in reply to Peanut31

Thanks peanut. I've been a bit loathe to go the T3 route with having to take so often but I'm at the point where I can't stand the brain fog anymore! Hope you find a solution soon.

When I had brain fog on T4 alone, i went on to combined T4 and T3 and found the brain fog disappeared quite quickly.

Olsbird in reply to lisabax

Thanks. Think I will give it a go again and see what happens. Thx again.

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