Thyroid UK
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Don't Keep your thyroid medications in a warm room or in fridge

Just want to share my experience about effect of heat on thyroid medications,

I leave my thyroid medications in a room that might not have A/C all the time, here in middle east, it means it can easily reach over 30 degrees celsius. I noticed a sudden change in how I feel and then felt like I'm not taking any thyroid medications. The heat damaged the medication.

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Thank you for posting that. In some years, I have posted a general warning as the warmer weather arrives. Didn't think to do so at all this year!

The documentation for one of the UK makes of levothyroxine expressly says:

6.4 Special precautions for storage

Do not store above 25°C. Store in the original package and protect from light and moisture.

If you, or anyone else, thinks to store it in the refrigerator, take care. The problem is that when you take it out, condensation can very quickly occur. Levothyroxine needs to be kept in the dark, in the not too warm, and in the dry - but even the desiccants sometimes used in bottles of tablets can make it too dry!

Yes - have been in the over-40s in the Middle East. You know its a warm country when they fit chillers to the swimming pools. :-)


Ooops!! I keep my NDT in the fridge all the time. I decant tablets into an airtight container and just dose everyday from the fridge, they never see the light of day. I have often wondered about the transit of the tablets though, although sealed, they have come from a hot country through the mail system.

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We can never know about the in transit treatment but, hopefully, it won't be too extreme and should only be for a few days. Storing for months, or years, in poor conditions is likely worse.

In Australia, it is mandatory to keep levothyroxine in the refrigerator. Otherwise it can't last to its expiry date.

The problem is that if you have the tablets in a pot and take it out of the refrigerator, open it, take out one tablet, and put it back, and repeat every day, the tablet(s) that are in the pot for longest will be most affected.


Thanks helvella, I will re-think my strategy when I get a new batch. The damage, if any, is already done so may as well finish up what's there.

Thanks again

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Hi Helvella - how is T3 meds best kept. They are in foil

blister packs ?


I would do the same as with levothyroxine - in a cooler room, in the dry, in the dark. And left in the foil blisters until needed.

However, that is based on guesswork - I really don't know if it is less or more stable than levothyroxine.


Thanks Helvella


Mercury Pharma only mention protection from light.

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NDT'inserts warn against refrigeration... It is supposed to be stored at room temperature.


Thanks for that information deceived, the ones I use say store in cool, dark, dry place - no warnings about putting in fridge, or even optimal temperature.


After this indecent, I refilled my levothyroxine and put it in the fridge. After a few days, I realized that I'm getting the same symptoms I got from damaged levothyroxine. This tell me that this medication is very sensitive for both hot and cold. This is what I found from drugs website:

Store levothyroxine between 68 and 77 degrees F (20 and 25 degrees C). Brief storage at temperatures between 59 and 86 degrees F (15 and 30 degrees C) is permitted. Protect from heat, light, and moisture. Do not store in the bathroom.


Really interesting 😊 I've never as yet had to store elsewhere as my house is cool in the summer so it's never crept over the 25C. I didn't know about the fridge -that would have been my instinct to do so temporarily until temperature dropped. In uk unlikely to be more than a couple of days!

So if we do have a freak heatwave with record highs -what do people do?

When I've travelled abroad to hot climates I've always had aircon so not a problem. I accept the few hours in transit could potentially be a problem but in reality I carry then with me (cool air cabins etc) so that it is minimal when I'm actually in the heat with them. I take mine during the day but I carry a daily tablet holder so the rest is kept in the cool. :)

What do you do when you travel to hot climates?


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