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Thyroid UK
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Why are all brands of Levothyroxine (100) not the same?

I have been on levothyroxine (100) + liothyronine for over 12 years and had no problems with these meds until recently. My chemist supplies different makes every month.

Recently, I've had 2 different brands that cause me problems - severe headaches, really hungry, weight gain etc etc. In short all the problems associated with a thyroid problem.

They are a Forley Generics Ltd brand (PL16201/0002) and P L Holder Actavis brand (PL01420105). My local chemist refuses to order in anything for me, insisting I accept what they have. Any help/advice would be greatly appreciated.

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37 Replies

Hi dizzy,

Have you had the Forley Generics packaged levothyroxine very recently?

I ask because the Forley Generics name has at least in theory, not been in use since it was merged into Mercury Pharma (early 2012), which company name has in turn recently changed again to Amdipharm Mercury.

Have you had any thyroid blood tests done whilst taking these medications to see if there's a change in your levels?

Normally, I would suggest that if your usual pharmacy is not helpful in obtaining specific make of levo for you, then it makes sense to change to a more helpful pharmacy. However, when it comes to levothyroxine, there are only three makes here in the UK, which are:


Mercury Pharma (now Amdipharm Mercury and previously Goldshield, Forley Generics)

Wockhardt (only available in 25 mcg tablets)

The ony other options for levothyroxine would be the more expensive liquid version, marketed here by Mercury Pharma and Teva.

Up to date info on current thyroid medications available in the UK can be found on our main website here:


If you believe there is a problem with any medication (not just levo), then you can (and ideally should) report it via the Yellow Card scheme.


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Thanks for your reply.

I was supplied with the Forley one very early last year - the first time I'd ever had a problem. No, I haven't had blood tests whilst on these meds - blood tests aren't given on request at my doctor's surgery. I'm going purely on how ill I feel when taking them. I lasted 17 days with the Forley tabs and only 10 with the Holder tabs - I've been very much worse this time.

I've been reluctant to change pharmacies - I live in a village and another pharmacy is a long way away, also other pharmacies tend to expect me to deal locally and aren't too helpful. That said, I am going to try another pharmacy.

I am aware that there are only three different manufacturers but they seem to issue their tablets in different colours/shapes of box as I've had considerably more than three different boxes in the past year.

This makes it very difficult to keep track of what I'm taking.

Is anyone else out there having problems with the strength of thyroxine 100?

No, I haven't had blood tests whilst on these meds - blood tests aren't given on request at my doctor's surgery.

Your GP has an obligation to ensure that your thyroid medication is appropriate for you. If you feel things have changed in direct correlation with a change of levothyroxine make, then you should go back and explain this to your GP and ask for a re-test.

Hi. Regarding Wockhardt, I have been dispensed this in 100mg tablets as well as 25mcg.

great advice... just to add there is also almus brand in the uk too...

im currently trying to find a brand that suits me too dizzy864..

ThyroidObsessed, Almus is NOT a brand, it is simply the name on the box of levothyroxine dispensed by Boots Pharmacy. Inside the box you will find that the blister packs and PIL are from one of the other manufacturers (usually, but not always, it will be Actavis)

See info on the main website here, under UK - Synthetic Levothyroxine (T4) Tablets thyroiduk.org/tuk/treatment...

This post is four years old now and may contain out of date information, so I'm closing the thread to comments.

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Am I right in thinking that your GP can state on the prescription which brand you require, instead of just putting 'levothyroxine' and then leaving it to the chemist to give you whatever brand they have to hand.

About a year ago, my brands changed every time I got a new prescription but now I seem to only get Actavis.

I shall repeat what I replied on a previous blog with minor changes:

It is perfectly reasonable to ask for a specific brand on your prescription if you feel it will help. There are some issues with so doing:

a) If there are supply problems and your preferred formulation is not available then the pharmacy may not be willing to substitute without referring back to prescriber. (Even though I think they might now be allowed to do so);

b) If the pharmacy has, say, Eltroxin Levothyroxine 100 mcg but your prescription says Mercury Pharma Levothyroxine 100 mcg and your pharmacist does not understand they are the same. Again, probably refer back to prescriber;

c) If there are changes in the market. Maybe another formulation (or simply another branding of an existing formulation) becomes available. Any such change would require you to get your prescription changed if you wanted to try it. Indeed, even the recent company name change (Goldshield to Mercury Pharma and now to Amdipharm Mercury) might have caused a minor hiccup;

d) If you ask for Mercury Pharma Eltroxin, someone, somewhere is making more money out of that - probably at some cost to the NHS - for exactly the same tablets. (I am not 100% clear how these pricing issues affect money. Anyone with good knowledge of such things able to clarify?) Which seems, shall we say, unfortunate in a cash-strapped era;

e) If you get Almus or Lloyds named, then you are restricting your choice of pharmacy somewhat.

I feel that, with only two formulations at each dosage, I prefer the flexibility of a prescription written in a generic way and simply asking the pharmacy which they will supply before giving over the prescription form. That leaves me free to go round every pharmacy and to accept any variant of livery/packaging/branding.

So if there were only one pack of "Helvella" Levothyroxine in the area, I could get that packet without any artificial restriction due to the way the prescription was written. (That is, if I can find it! Might take a lot of calls or pharmacy visits. :-) )



Thanks for your reply.

No, that can't happen here. I asked my pharmacist about that. She told me the GP can only prescribe the tablets, it is up to the pharmacist to supply what make they choose. I asked if he could at least exclude the brand I was having trouble with on the prescription, but was told he wouldn't do that and they wouldn't be able to take any notice of it if he did.

My local pharmacist gets sent different brands by their supplier - based on what is cheapest at that particular time. My pharmacist has no say in what is sent and is not prepared to order something specific for me. I never get the same box two months running, which I don't think is good for anyone.

My local pharmacist gets sent different brands by their supplier

This is typical of most if not all pharmacies. However, if they value your custom, they will bend over backwards to be helpful. I found out the best way is to ask which make they currently have in stock, and if it's not the one I want, then ask if they will try to obtain my preferred make. If the answer is 'no' they won't help, then take the prescription elsewhere. Yes, I know it's a pain having to trawl round different pharmacies, but if it's the only way then in the long run it's better than suffering. We have to take control and not allow our lives to be controlled by pharmacists!

Hi dizzy! Just to say I had been having Mercury Pharma levo for over 6 years, then while we have been having this problem with supply I was given Actavis and was really ill and had to stop taking it. My pharmacy suggested I get my GP to write Mercury Pharma on the prescription, which he did for me. Although the pharmacy couldn't give me Mercury Pharma because of the supply problem, they did give me Eltroxin, which is the same. So try asking your GP to write on your prescription a brand that suits you. Keep well....

Jen x

Thanks for your reply.

It would seem that my local pharmacist does not value my custom because they will not order anything in for me. It's difficult at the moment to pick a brand I know I'm ok with because I have had so many different boxes over the last year.

I've read on the I/N this morning that there has been problems in the past with levothyroxine losing some of it's potency with time. I noticed that the levothyroxine that I'm having problems with - I think is much too weak for me - was manufactured in June 2012. ( it's a year old ). I wondered if that could be part or all of my problem. It has a use by date of June next year so it is well inside it's date. But I do usually get levothyroxine that is fresher.

Has anyone else had problems with levothyroxine when it gets "old"?

The PIL (patient information leaflet) is the key to knowing who the manufacturer of your levothyroxine is. Regardless of what colour, shape and wording is on the box, the manufacturer, product license holder etc is stated on the PIL, which will be any of the three names I mentioned above.

Previously, there was another make called Teva. This make was withdrawn last year following potency problems. Many patients had issues with this make over the previous couple of years. Some info about this is on the main website news page:



I was one of those who fell fowl of the Teva Brand. Prior to its withdrawal my symptoms were gradually getting worse until in the end I could hardly get out of bed. Only from the web did I learn abouts its withdrawal and my chemist was still dispensing it. My doctor didn't even know about it.

I said above that my supply has now stabilised to Actavis, but in fact the 100mcg are Activis and the 25mcg Wockhardt.

With 2 brands on the go, how would I ever know which, if any, were not working for me.

Yes, it's a real problem. Actavis don't make 25mcg tablets, so we're stuck with MercuryPharma and Wockhardt for those. I have heard of the occasional patient who has managed to persuade the GP to prescribe the full dose in 25mcg tablets so that they could stick with only the Wockhardt brand.

In the MHRA report on Levothyroxine, sections 4.3 and 4.4 go on about stability over time and related issues:


It is, of course, the patient's responsibility to follow the advisory storage information once the product is in their possession.


If you feel there's a problem with the potency, then as I said above, you should go back and explain this to your GP and ask for a re-test. And also put in a Yellow Card report.

Hi i usually use Mercury Pharma levo, but have been to boots to collect my T3 and all they have in levo is the make Almas hhas anyone heard of this make Thank you x

Almus is Boot's own name, and Boots do not make levothyroxine. If you look at the PIL you will most likely find that the tablets are actually Actavis.

Oh thank you will see what this match is like then and get my levo from another chemist next time thank you for the quick reply x

To look back at the original question, why are they not all the same?

Look at it like this, if they were all the same, then there would be no possibility of changing to another formulation if you find one does not suit you. You would, effectively, have absolutely no choice.

Perhaps it as well that there are two formulations at each dosage?


Makes complete sense to me! What works for one doesn't necessarily work for another.

With respect, should not 100mcg of Levothyroxin be exactly the same no matter who and which manufacturer supplies it? If it was, then we would not be having this problem and it would not be such a lottery. If all medications were made with such random outcomes then it would be chaos!

Personally I have issues with Activis and have to make sure that my T4 is either Eltroxin or the Mercury Pharma levo. No doubt I am going to be stressed out next time I go to get my script because of this company and their ridiculous antics. In any other line of business they would be told to stuff it and we could take or business elsewhere, but no they have it sewn up and we are just muppets dancing to their tune. :-(

should not 100mcg of Levothyroxin be exactly the same no matter who and which manufacturer supplies it?

Of course, in a perfect world, that's obviously what would happen! Unfortunately, even if the pills were all perfect, we humans are not :) What happens to a levothyroxine pill in your digestive tract won't necessarily be the same as what happens to it in mine. The different excipients have a part to play in this, not just the active ingredient levothyroxine.

I agree :-)...but ....at least there should be a level baseline just like with other meds! You do not hear about these discrepancies with other medications made by different pharmaceutical companies....well at least I have not.

Absolutely agree. It seems to me to be a basic requirement that ALL tabs should contain the active dose stated.

The rules on potency of levothyroxine are that they must be in the range 90 to105% of claimed potency. Whenever I have seen results of assays in recent years, in the UK, the actual content has been in that range.

The lower end tends to be approached as the tablets age - levothyroxine does deteriorate over time.

Because of this deterioration, plus a small variation at manufacture, it is impossible to make every tablet have exactly the same amount of levothyroxine in it.

When Teva was withdrawn, it appeared to be the impact of an ingredient preventing the dissolution of the levothyroxine rather than the actual active ingredient content being wrong. Of course that should not have been the case but no-one appears to have done anything beyond not realising that this could happen.

Levothyroxine is a special case - very slight under- or over-dosing over a long period of time does seem to cause problems in some people. I suspect you might not notice large variations in medicines such as paracetamol where the precision of dose is nowhere near as critical.


I'm the other way round, I can't tolerate Mercury Pharma Levo (or their Liothyronine for which there is no alternative in this country) so always make sure I get Actavis, and since 25mcg tablets tend to be Mercury Pharma and not Wockhardt I get extra 50mcg tablets and cut them.

Thanks for all your replies. I looked at the external link to the MHRA site, which although very interesting did not help with my question about how long levothyroxine will maintain at it's original potency. My tablets are always stored in the advised way. The MHRA report does not state when the tests were carried out on the tablets. I assume it was when they are first manufactured as no mention was made of them being tested after any period of time. I am of the opinion that my problem ( this time ) is to do with the age of my pills rather than the brand. The pills were a year old, I have no way of knowing how they were stored for 11 months prior to my getting them. They were still supposed to be ok for another 12 months, hence my last question asking about how long levothyroxine remains as potent as the day it was manufactured.

My original question about why all levothyroxine 100 is not the same was not referring to individual formulations - of course there is always going to be something one person can tolerate and another can't - I was referring purely to the potency. Levothyroxine 100 should always mean levothyroxine 100 and I'm not convinced it does. Teva being one example.

I think this section does indeed address the issue of potency across the full shelf-life of the product.The same section also addresses what is meant by 100 micrograms claimed potency:

4.5.2 Drug Product - Assay Limits across Shelf-life

As discussed earlier in this report, while levothyroxine is not considered to have a narrow therapeutic index, precise dosing is crucial to maintain a patient’s quality of life and to avoid long-term side effects. This was recognised in 2007, when an Expert Advisory Group to the BP Commission considered input from manufacturers and the action by the USP to tighten assay limits across shelf-life. They recommended that “to address any potential clinical concerns whilst avoiding placing a prohibitively restrictive burden on manufacturers, limits of 90.0 to 105.0 % should be adopted". This recognised that levothyroxine sodium degraded on storage, but also recognised the concerns over the therapeutic range of the product and reflected the data provided by manufacturers. Re-examination of these limits in March 2012 by the Medicines for Women’s Health Expert Advisory Group and the Commission for Human Medicines has confirmed that these limits are considered appropriate; variation within these limits are highly unlikely to be clinically significant.

As I read the report, there is no claim that Teva did not have the correct amount of levothyroxine in it. The problem occurred in failure of dissolution which affected the ability of the product to reliably deliver the claimed potency. Subtly but importantly different.

If you believe that the product you have was not delivering what you expected, then you should most certainly consider retaining samples and filing a Yellow Card report. I would do so.


If I am understanding this correctly - I could have a dose of 105% of levothyroxine 100 for several months, then be supplied with a packet that is near to the end of it's shelf life which is only 90% of it's potency. This means a drop of almost 15% in my medication from one day to the next as I finish one packet and start another.

This seems to me to be unacceptable. Surely, I have the right to expect my meds to be the same strength every day? Even the above article makes it clear that the correct dosage is absolutely vital.

Do all manufacturers place the same shelf life on their levothyroxine packets?

Your arithmetic is OK.

If you feel it is unacceptable, you will need to persuade the MHRA that it is wrong. They are the regulators. They establish the regulatory regime.

Do bear in mind that if reducing the potency range to, say 97.5 to 102.5% (or some other very tight range), then the manufacturers will likely do one or more of:

Increase the prices.

Reduce shelf lives.

Reduce range of dosages (e.g.they might manage at 100 micrograms but not at 25 or 50).

Change formulations which could introduce new problems to patients.

Get out of the market.

Change packaging.

Impose strict storage conditions post-purchase. (Australia requires refrigeration despite the issues that can cause with condensation/humidity.)

Be careful of what you wish for! :-)

As there are only three companies in the UK responsible for setting shelf lives on their products, I suggest that you contact them directly and ask what shelf lives they set.

You are also entirely ignoring that the specified variability is only partly due to deterioration over time. Some variation is inherent in any manufacturing process so two tablets from the same pack could vary by a noticeable percentage. Let alone from two batches.

The requirement is simply that they maintain their potency, within the specified range, from day one to end of shelf life.

Do also bear in mind that there comes a point at which our own human variability from day to day, season to season, could be greater than the intra-product variability. One day you eat something which affects the thyroid hormone processing. Another day you run a marathon. Or you take a vitamin supplement.

The end result of having sufficient but not too much thyroid hormone is what matters and, I believe, that would be better targeted by things such as personal testing kits (on the lines of those available for diabetics) rather than getting too wound up by effectively unavoidable issues of variability.


I wanted to say a few things about pharmacies ordering specific brands of levothyroxine for patients.

1. Independent pharmacies should usually be able to order a particular manufacturers product, assuming that it is in stock. The 4 largest wholesalers in the UK: Phoenix, Alliance, AAH and Mawdsleys all offer pharmacies a choice of product when ordering. Other wholesalers simply sell 'levothyroxine' but the manufacturer may vary, except for OTC Direct who always sell the Almus brand for 50mcg and 100mcg. OTC is a wholesaler of generics to independent pharmacy.

2. Pharmacy chains may have ordering restricted by Head Office, but some are more flexible than others. It is usually possible to order a specific product by telephoning the wholesaler, even if computerised ordering is blocked.

3. Due to the small number of manufacturers, it is easy to obtain a specific product, although the packing may vary. Avoid having prescribing written as Eltroxin, due to supply issues the pharmacy may not be able to dispense any medication. Instead, simply have prescriptions written as levothyroxine and find a helpful pharmacy.

4. TEVA as currently distributing AMCo/Mercury's 50mcg and 100mcg tablets, instead of their own. In order to obtain the AMCo/Mercury product, pharmacies can order TEVA from their wholesaler (if the AMCo/Mercury product is not listed separately on the system). Major wholesalers always list TEVA and Actavis separate on the system, because these companies offer specific buying schemes to pharmacies. These products can therefore be ordered by name. The AMCo/Mercury product is not always listed by name, but is generally supplied when ordering the wholesaler's own line. For example, Phoenix list levothyroxine 100mcg as follows:

Levothyroxine 100mg tabs ACTAVIS (28)

Levothyroxine 100mcg tabs ACTAVIS (1000)

Levothyroxine 100mcg tabs TEVA (28) - Mercury will be supplied at present.

Levothyroxine 100mcg tabs PHD/Phoenix (28)

If ordering Phoenix's own PHD line, AMCo is likely to be supplied but this is not set in stone.

5. Lloyds and Almus are not manufacturers, but simply have Actavis supply levothyroxine in special packaging for them. Lloyds branded packs are only supplied via AAH pharmaceuticals to Lloyds pharmacies. Almus branded packs are supplied via Alliance Heathcare to Boots and independents, and by OTC Direct and occasionally other wholesalers to independents.

6. The price of different brands varies by up to about 60p per pack of 28. Although not available at the moment, Eltroxin is not very different in price to the unbranded packs. Because there are few manufacturers and hence minimal price competition, and due to the expectation that generics will be sold for less than Eltroxin, the existence of Eltroxin is probably partly responsible for the low cost of levothyroxine in the UK - it effectively provides a maximum price for the generics. In the absence of the Eltroxin brand, the generics may tend to increase in price.

And Teva 25 microgram tablets always were Mercury (well, at the time they were Goldshield).


They were indeed. It's very common for generics manufacturers to distribute other manufacturers products when they don't have their own version. TEVA are particularly keen to promote themselves as providing a very wide range of medicines, and as a result they distribute other companies products for some lines. TEVAs furosemide tablets, for example, are made by Bristol pharma. TEVAs nicorandil tabs (for angina) are made by Sanofi-Aventis.

Are they just "distributing" with different branding or do they actually make the medication? (Teva that is)

At the moment, TEVA do not manufacture levothyroxine in any strength. They used to manufacture their own 50mcg and 100mcg tablets.

TEVA are currently distributing the AMCo product (Forley, Goldshield, Mercury and AMCo levothyroxine are all the same. The company keeps changing its name due to mergers and acquisitions, and so the packaging may vary according to when it was manufactured. AFAIK, the most recent packs are branded Mercury.).

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