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Markings on Mercury Pharma levothyroxine tablets

In April 2016, updated Patient Information Leaflets for Mercury Pharma levothyroxine tablets were posted on the Electronic Medicines Compendium site. The dates within the documents are November 2015. At the same time, I think, they updated the company name to Concordia International on EMC (but not on the documents themselves).

The reason I am posting is to highlight that the actual tablets themselves are changing.

The old tablets were marked FW41 (for 25 micrograms), FW21 (50 micrograms) and FW31 (100 micrograms). A rather odd and seemingly haphazard identification scheme.

The new markings are LT on one side and 25, 50 or 100 on the other side.

This does seem to be a more rational marking scheme (assuming LT is being used as an abbreviation for "levothyroxine").



[The same changes were also made to the documents for the product when packaged with the Eltroxin branding - which is not available in the UK.]

6 Replies

Just realised, we have had a couple of posters mention they got levothyroxine in a bottle recently. And there were some "Is there a shortage of MercuryPharma levothyroxine?" questions over the past few months.

Given the change to the actual tablets described above, perhaps MercuryPharma (Concordia International) intentionally tried to squeeze all stock with the old markings out of the system? Maybe they reduced inventory levels as they changed over? It could make sense of the rather sporadic "shortage" issues.

Suggestion to everyone:

If you get medicines offered without a Patient Information Leaflet, ask for one. And get the batch number and expiry date in writing (preferably by the pharmacy directly onto their label). These are fundamental things that must always be supplied if you request them.


I have just got my latest prescription for thyroxine. I take 100 and a 50 totally 150. My new 50 tablets were mixed. One strip was as usual with 50 on one side but the other strip in the same box had fw21 the leaflet didn't mention fw21. Very confusing.

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There is a very good reason that the leaflet didn't mention FW21. (And very well spotted!)

FW21 is the marking that used to be put on Mercury Pharma 50 microrgam levothyroxine products.

In my book, the contents do not match the PIL. That should be grounds for a recall of the product if it is due to Mercury Pharma. (Even small mismatches between product and PIL have been such grounds before.)

You have absolutely NO idea whether this is legitimate or not. The FW21 tablets, well, they could be old stock, someone in a pharmacy could have shoved in a strip from another (old) pack, or any of numerous other possibilities. Including MP getting rid of old stock by subterfuge.

I don't want you to feel pushed into doing anything, but it would be perfectly sensible to put in a yellow card report, and go back to pharmacy. Make sure you do NOT let the pharmacy have the faulty tablets.

Photograph them (if you can), and the PIL and the box.


On the other hand, if you don't want to raise the issue, be re-assured that there is a sensible explanation. Even though it is clearly an error.

Everyone who gets MP levothyroxine, please try to check your product and see if yours matches PIL to product.


Just looked at my levothyroxine blisters (though they are not MercuryPharma) - the actual blisters have expiry dates in them. Suggest you check them. They must match the expiry on the box.

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Thank you for your reply. Unfortunately I have already given the tablets and box to my chemist. But made sure he checked that they were ok to take (he got in touch with the company ) but in my view just seems wrong. .

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I too have had brown bottles of Mercury Pharma tabs.I got one bottle of 100 and one bottle of 25,I nearly got them mixed up and nearly took 200 !I think this is dangerous for older patients or those with bad eyesight.


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