Generic Drugs: What They Are, How They Work, and When to Choose Them

When you hear generic drugs, lower-cost versions of brand-name medications that contain the same active ingredient, dosage, and intended use. Also known as generic medications, they make up over 90% of prescriptions filled in the U.S. But that doesn’t mean they’re all the same in how your body responds. The FDA says they’re bioequivalent—meaning they work the same way in your system. But if you’ve ever switched from one generic to another and noticed your blood pressure spiked, your seizures returned, or your stomach rebelled—you’re not imagining it.

That’s where pharmaceutical excipients, the inactive ingredients like fillers, dyes, and coatings that help the drug work or stay stable. Also known as inactive ingredients, they don’t treat your condition—but they can change how fast or how well the active drug gets absorbed. Two pills might have the same amount of lisinopril, but one uses a different binder that slows release. For most people, it doesn’t matter. For someone on antiseizure meds like lamotrigine, even a 5% difference can trigger a seizure. That’s why doctors warn against switching generics for NTI drugs—narrow therapeutic index meds where tiny changes have big consequences.

And then there’s the money game. PBM negotiations, the opaque deals between pharmacy benefit managers, insurers, and pharmacies that set what you pay at the counter. Also known as pharmacy benefit manager pricing, they often make the cash price cheaper than your insurance copay. How? Through spread pricing—where the PBM charges your insurer more than they pay the pharmacy—and clawbacks, where you get billed later for the difference. That’s why you might pay $10 for a generic on insurance but only $4 if you pay cash. It’s not a mistake. It’s the system.

What you’ll find in the posts below isn’t just a list of generic drugs. It’s the real talk behind them: why some people can’t switch from brand to generic without problems, how excipients might be causing your rash or stomach upset, how insurers set prices that don’t make sense, and which medications are safest to swap—and which aren’t worth the risk. You’ll see how genetic testing can predict if your body will handle a generic statin, how green tea affects blood thinners even when you’re on generics, and why a $3 pill might be worse than a $30 one if your body doesn’t absorb it right. This isn’t theory. It’s what happens when you take your meds every day and wonder why things aren’t working like they should.