Thyroid UK
82,752 members97,780 posts

Do generics work?

Hi everyone. I've been taking 100mcg levothyroxine now for a number of years. Truth is the cheapo variety I get from the GP doesn't seem to work. For example; I forgot to order my prescription one week and ended up not having medication for nearly two weeks, due to weekends. I don't feel any different off it!

When I lived in Scotland, the GP who diagnosed me said she'd never seen a TSH so high. Now they're telling my bloods are normal, how can that be when I haven't had any for two weeks?

6 Replies

Generics do work but the efficacy of each seems to vary from person to person. For example, someone taking 100mcg on one generic may only need 75mcg on another or 125mcg on another. Usually the difference isn't as big as that between the brands but it can be in some people.

It can take a while for your TSH to respond to stopping your medication and it also takes time for the thyroxine to leave your system.

It could also be that you had a transitory form of hypothyroidism that has now resolved.

When you say 'normal', what exactly is your TSH? It may have gone up and be still going up.

I know I would certainly feel very unwell after stopping my thyroid medication for that long. Very interesting!

I would recommend getting another thyroid test in about 6 weeks and sooner if you start to feel unwell without your thyroxine. Hopefully you won't feel unwell again :)

Carolyn x


Thank you, I'll ask for them to check my TSH...they never did tell me what it was here in England, they just said it was normal.


It could be that you have antibodies to TSH itself.

Some, but not all, TSH tests are affected by TSHab and result in high TSH results which do not reflect the true TSH level.

So my suggestion is that the Sottish test was registering macro-TSH whereas the non-Scottish one is unaffected by macro-TSH. That would explain you having an incredibly high TSH test result but not needing more than 100mcg and not feeling much, if any, different when not taking it. Most people who really had such high TSH levels would be very, very unwell, would need a higher dose, and would feel awful if they stopped taking it.

This is only a wild guess.

There is nothing cheap about the levothyroxine you get from your GP. (Except the cost - it is indeed an inexpensive medicine.) If you went to the finest pharmacy in the UK with a gold-plated prescription they could only supply exactly the same three variations we all get.



Yes I have tested positive for antibodies.

I was just wondering about the efficacy of the drugs. I do know some drugs are different regarding generics vs branded. I work as a nurse so have first hand evidence.


I didn't mean the "usual" Thyroglobulin or Thyroid Peroxidase antibodies but specifically TSH-antibodies. It is very unusual to be tested for them.

We only have three formulations of levothyroxine and they are all regarded as generic. (There is an oddity for Eltroxin which Mercury Pharma claim is the same as their levothyroxine but which is also dispensed as if it were a generic.) So there really is no "brand" for the generics to be less good than!

In the USA you see arguments about these things all the time. Interestingly some people have found a generic better than the currently unavailable Levoxyl brand. You also see Lannett disparaged and Unithroid praised - when they are actually identical to each other.

I certainly accept that people feel better on one formulation than another - but am unconvinced that branded or generic is of any significance whatsoever - either here or anywhere else I have read about. But randomly changing from one to another can be a problem.



thank you for your help


You may also like...