Thyroid UK
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Selenium overdose?

Maybe I have a hyper sensitive metabolism but I have experienced adverse effects when I take selenium supplements-eg palpitations/hyper feelings.

Now I supplement with 1x alternate days and sometimes 1/2 alternate days. Seems better for me.

It's a good supplement for hypothyroidism but it's powerful and I heard somebody mentioned they should only use alternate days as builds up on aggregate in your system.

Anyone had similar experiences? many Thanks-oh and a very big hug to all the brave souls who are working night shifts or long shifts or even working full time full stop with thyroid probs-you have my heartfelt sympathy. I'm now part time having down sized my already down sized life. As for no pension till 66!!!!!!!!!!!!!! OMG.

7 Replies

It might help if you identified the selenium supplement you are taking. People do seem to respond differently depending on active ingredients.



High strength. 200mcg.

Dicalcium phosphate, microcrystaline, cellulose D alpha tocopherol stearic acid magnesium stearate silicon dioxide active ingredients.


Have you tried brazil nuts for selenium?

2/3 pre day should supply all you need


Thanks for the comments about work. I had to give up work ( 3 and 1/2 months ago) so I could work on medication and getting symptoms stabilised . I know I will never be able to do the same level again as still struggle with cognitive , mental slowness issues and crashing tierdness. Such a worry getting back in the workplace, as I left my job as adjustments were stopped.


A friend in France struggling with thyroid problems was advised by a pharmacist there to take selenium but only on alternate days.


Thanks-v much-good advice as every day too much. What an informed pharmacist! Must have had close relative with thyroid problems-ours would never have that info.

Feeling much better now dose has reduced.


There's a paragraph on why it can go wrong.

You have to be careful to avoid selenium poisoning but you can take it for about 90 days.


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