Thyroid UK
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Different pharaceutical companies?

I have Hashimotos, and take 100mcg and 25mcg Thyroxine daily. For reasons that will take far too long to explain, I filled two difference prescriptions at two different chemists. One chemist gave me 100mcg and 25mcg from two difference pharmaceutical companies. I have been taking these for approx a week, and have started to feel ill again, after being stable for a number of years. When I looked at the boxes of tablets I realised why! The other chemist gave me tablets both from the same pharmaceutical company, and which I have taken most of since being diagnosed, I have taken these for the last couple of days, and the symptoms have abated and I feel fine again! But how can this be? Surely the drug strength should be the same in ALL tablets, immaterial of the manufacturer? Has this happened to anyone else? Merry Christmas!!

7 Replies

BeanyJeany, the active ingredient Levothyroxine Sodium will be the same in all three makes Actavis, Mercury Pharma and Wockhardt. The fillers &/or the way they're formulated may differ however and can significantly affect how patients respond and feel. Some members feel Mercury Pharma has more potency than Actavis while others, like me, prefer Actavis to MP. Wockhardt has less fillers than Actavis and MP which suits some members better although they are only available in 25mcg.

Make sure to request your preferred make when you hand over your prescription to be dispensed. If your script is sent electronically make sure your pharmacist notes on your dispensing record that you should only be given your preferred make. Check what you are given before leaving the pharmacy as they're unlikely to change it once you've left the shop.


It may not be the 'hormone strength' (T4 and T3 being hormones) but it can be the additives etc used in them which affect you.


Hi yes this same has occured to me . Was on activis 100 mcg and my dosage was increased to 125 so 25 was given by wokhard , from day one i am have severe headaches , pain in temple high blood pressure.

Talked to doctors he said stop 25 mcg for 2 days symptoms gone... I guess its the fillers !!


Well at least I know its them and not me! My usual one is Mercury Pharma, the other two, which don't obviously suit are Wockhardt and Actavis. I must keep my wits about me when I next have my prescription filled. Thanks for the help folks x


If you want always to receive one make, I suggest you discuss with the pharmacist(s) whether they can make a note on their records. Many are very helpful and will do their very best to achieve this.

(Far better doing this by friendly conversation than what is sometimes suggested, getting GP to specify on the prescription. If you do that and there are supply issues, you can have problems.)

A few years ago the Teva make had the right amount of levothyroxine but one of the other ingredients was preventing the full dose from being delivered. The licence was withdrawn.


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I had serious problems with the Teva 100mcg (under dosing) and then went on to Actavis I was fine until I needed an increase to 125mcg and Actavis don't do 25mcg so was given 100 Actavis and 25 MP. Big mistake, felt very unwell dropped back to 100 Actavis and improved. Then found out about all the other vitamins etc that I needed and so far have been ok on 100mcg Actavis only + loads of supplements. I now know that if ever I needed 125mcg I would ask for a prescription for 100 mcg + 50 mcg and use a pill cutter or take the 50 mcg on alternate days. I will never take any MP levo tablets again and daren't try Wockhardt.


I find Wockhardt fine, it has less fillers than the others, so maybe is 'in my head' that it's the best one!


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