Quick question 🙋‍♀️ Does the heat affect the Levo dose?

[SarahJane1471]

I’ve been feeling jittery and shaky in this heat. Could the heat affect how the Levo is working ie make me one a little overdosed?

[Anthea55]

Yes, it can affect you. Dr Peatfield, in his book, "Your Thyroid and How to keep it Healthy", mentions what he calls "the season factor".

"So the colder the external temperature, the more heat the body needs, so metabolism has to be increased, so more thyroid hormone has to be made. And if it cannot be increased internally, then extra has to be provided. The reverse obviously applies in hot weather and in hot climates. I have taught my patients to be prepared to increase their thyroid supplementation in winter and reduce it in the summer."

So it's worth trying a small reduction and seeing how you feel.

[SarahJane1471 in reply to Anthea55]

Thank you that it makes sense really. I will try a small reduction 😀

[JoVH]

Also, a point to make here. Don’t know where you are located but in Australia we must keep Levo in the fridge as heat and higher temperatures affects its efficacy.

[helvella Administrator in reply to JoVH]

I think if you read the Patient Information Leaflets for levothyroxine tablets in Australia, it depends on the make.

[JoVH in reply to helvella]

Best to read the product statement/consumer medicine information that comes with each brand or ask a pharmacist. My doctors have always insisted I keep levo (no matter what brand) refrigerated. It is always put into a cold store pack whenever I pick up my prescription from the pharmacy. My brand (Aspen Eutroxsig) specifies it be stored refrigerated at 2-8 degrees C. Where unavoidable (eg. In warm climates where temperatures regularly exceed 25 degrees C), an in-use blister strip may continue to be stored in a refrigerator at 2-8 degrees C.”

[helvella Administrator in reply to JoVH]

Fully agreed - read the documentation!

Oroxine and Eutroxsig both say what you posted.

Aspen Eltroxin simply says to store below 25C.

tga.gov.au/sites/default/fi...

As does Sun Levoxine:

nps.org.au/medicine-finder/...

[SarahJane1471]

So heat can make it LESS affective?

[Andie222 in reply to SarahJane1471]

This is interesting. Perhaps we should be keeping levo in the fridge in the UK during this heatwave?

[helvella Administrator in reply to Andie222]

The problem with refrigeration is two-fold.

Anything below about 5C could start to cause issues with the hydration of the levothyroxine. Although defined as anhydrous levothyroxine (in terms of measuring it as an ingredient), real-world levothyroxine is hydrated. But as things get colder, the water molecules can condense on the cold surface (e.g. inside a pot) changing the hydration of the levothyroxine.

If you store a pot of levothyroxine in a refrigerator and regularly take one or two tablets out, there will be a tendency for water in the atmosphere to condense which will also lead to issues.

We all have different circumstances which makes it difficult.

If necessary, the warmest part of a refrigerator, in an absolutely sealed container would probably be fine. But if you have a room which is somewhat cooler than the rest of the house, that might be a better choice.

[JoVH in reply to helvella]

Best to read the product statement/consumer medicine information that comes with each brand or ask a pharmacist. My doctors have always insisted I keep levo (no matter what brand) refrigerated. It is always put into a cold store pack whenever I pick up my prescription from the pharmacy. My brand (Aspen Eutroxsig) specifies it be stored refrigerated at 2-8 degrees C. Where unavoidable (eg. In warm climates where temperatures regularly exceed 25 degrees C), an in-use blister strip may continue to be stored in a refrigerator at 2-8 degrees C.”