Eli5: what is the difference between a generic drug to the original drug, and why do some doctors will swear by the original drug?

Question

Eli5: what is the difference between a generic drug to the original drug, and why do some doctors will swear by the original drug?

In: 1046

Answer 1

My endocrinologist prefers brand; he says the consistency pill-to-pill is better. Because these are pretty small amounts that have big effects on metabolism (for my hypothyroidism), he wants that consistency.

As u/EvenSpoonier said, the active ingredients are very small amounts compared to inactive. If there’s poor pill-to-pill consistency of active ingredients, particularly if it’s poor batch-to-batch (one 90-day supply runs high, the next runs low), there could be negative effects. While the effects may not be severe, I’d rather avoid them.