It depends on your system. I would not say yess or no. It is a metablozim(sp?) issue. I have issues with the t4 only. Not the brand.
The brand names aren't always best. I started out on synthroid and didn't do well, but when I went to generic levo, my levels came up, and I felt a lot better. I'm now on Tirosint, though, which is a name brand, and doing well on it.
I switched from generic to a brand name because my endo insisted on it (I guess we have to pick our battles). At one time or another I've been on Synthroid, Levoxyl and generic, and I saw absolutely no difference between them. However, some people do have issues with fillers, and those vary maufacturer to manufacturer.
Interestingly, when my endo switched me from generic to Levoxyl (no dose change) my labs actually got a bit worse, and I had to up my dose of Levoxyl slightly.
I do fine on generic T4, which my doctor prescribes as only coming from Mylan. One of the issues with generics is that pharmacies give you whatever generic they have on hand when filling your scrip unless the doctor states otherwise, and not only does the FDA allow manufacturers of generics a plus-or-minus 10% variation in strength (in general and from batch to batch) from the brand name, but also each manufacturer uses different fillers, which have different absorption rates. Because T4 has a relatively long life in the body, once you've adjusted your labs for a generic from a specific manufacturer and make sure to CHECK that it's filled the same every time, a generic is OK imho. Also, a 3 month supply usually comes from the same batch, so that guarantees even more stability in your dose.
I don't personally feel that way about T3. The generic was substituted for the brand without my paying attention, and 4 months later I had a hyper-symptoms setback which caused the doctor to drastically lower my meds and that's taken me over a year to correct the hypo symptoms that resulted from THAT.( No Hashi's, maybe rT3 issue ) Once I figured out that the problems started with the substitution and made the doctor switch me back to the brand, I resumed getting better pretty quickly. That's just my experience, but because T3 is fast-acting and isn't stored in the body, it makes sense to me to take the formulation that has to be manufactured the same way every time and is tested as such by the FDA.
I've been on generic T3 for nearly 3 yrs and do fine with it, so once again, it's all a matter of how the body/mind reacts.
I was on generic Levo and got switched to Synthroid and did bad. It gave me such stomach issues ,my doctor thought it was the fillers. Went back to Levo and doing great again. Just depends on you.