What’s the difference between Levothyroxine and Synthroid?
The Difference?: What’s the difference between... - Thyroid UK
The Difference?
Synthroid is a brand name owned by AbbVie.
Levothyroxine is an Active Pharmaceutical Ingredient.
Levothyroxine is the Active Pharmaceutical Ingredient in the branded Synthroid product.
Synthroid puts enormous effort into marketing in order to maintain its market position in the USA and elsewhere.
Many people get on better with one make of levothyroxine than another. Some possibly get on better with Synthroid than other makes. But in the end, it is just a levothyroxine medicine. There is nothing amazing, super-special or radically different about Synthroid.
Are they the same
Each company that makes levothyroxine has their own recipe. So ingredients other than the levothyroxine itself can vary considerably.
We almost never know where the levothyroxine ingredient comes from - it is always supposed to be the same but there could be very slight differences. For example, the impurities (which all ingredients have) could vary - or they could come from exactly the same source.
If you are unable to tolerate acacia, or any of the other ingredients, you wouldn't want to take Synthroid.
Having said that, in theory a 100 microgram tablet should have the same effect whether it comes from Lannett, Sandoz, Pfizer, AbbVie, and whether it is branded just levothyroxine, Levoxyl or Synthroid.
So they do the same thing?
If you buy a pint of milk from Tesco and another from Asda, are they the same?
Well, the words on the label are the same, they both contain milk. Within the ability of machines, they will contain the same amount of milk. And probably the same nutritional information.
One could contain Welsh milk from cattle fed on fresh grass. The other could contain English milk from cattle fed on silage and other feed.
You might notice a slight difference in smell, if your nose is very sensitive. But most people could pour either onto their cereal, into their tea, make their cream of mushroom soup, and never for one moment detect any difference. A few will notice the different flavour.
One of those pints might be A1 milk whereas the other is A2 milk. This might be obvious (if labelled as A2 milk) or it might not be labelled. Those who are sensitive to the difference will notice - the rest of us probably not.