Cosmo20, I think we need clarification here. Levothyroxine Sodium is the generic name for the synthetic version of the thyroid hormone, thyroxine (T4). There are many BRAND names: Levoxyl (King Pharmaceuticals), Synthroid (Abbott Laboratories), Unithroid (Jerome Stevens Pharmaceuticals), Levothroid (Forest Pharmaceuticals). The generic and name brands may differ slightly in the amount of levothyroxine they contain, the absorption into the body and the distribution throughout the body. In other words, 37.5mcg of generic levothyroxine MAY NOT have the same effect as one of the other brands or the generic from a different company. So when switching between companies, the dose may have to be monitored. I hope that helps to clarify. Hoppy ;)