FDA Therapeutic Equivalency Codes: What They Mean for Your Medications

When you pick up a generic pill at the pharmacy, how do you know it’s just as good as the brand-name version? That’s where FDA therapeutic equivalency codes, a system used by the U.S. Food and Drug Administration to rate whether generic drugs are bioequivalent to their brand-name counterparts. Also known as AB codes, it helps pharmacists, doctors, and patients make confident choices about substitution. These codes aren’t just bureaucratic labels—they directly impact your health, your out-of-pocket costs, and even your treatment outcomes.

Every generic drug approved by the FDA gets an AB code, and that code tells you one thing: it’s been tested and proven to deliver the same amount of active ingredient into your bloodstream at the same rate as the original. If a drug has an AB1 code, it’s interchangeable with the brand. If it’s AB2, it’s still approved but may have minor differences in inactive ingredients that don’t affect performance. But if you see B or BN? That means the FDA hasn’t found it equivalent—and you shouldn’t swap it without talking to your provider. These codes exist because not all generics are created equal. Some manufacturers cut corners. Others use different fillers or coatings that change how the drug dissolves. The FDA’s system cuts through the noise.

These codes also connect to real-world issues you’ve probably seen in the posts below: why some antibiotic combinations are available as generics while others aren’t, how generic medications save thousands on healthcare costs, or why switching from one antihistamine to another might cause unexpected side effects. The same logic applies everywhere: if the FDA hasn’t confirmed equivalence, don’t assume it’s safe to swap. That’s why carrying medications in original containers matters when you travel—pharmacists and customs officials rely on those labels to verify what you’re taking. And when you’re managing something like diabetic neuropathy or high blood pressure, even small differences in absorption can throw off your whole treatment plan.

Understanding FDA therapeutic equivalency codes gives you power. You can ask your pharmacist: "Is this AB-rated?" You can check your prescription label for the code. You can compare costs without guessing whether you’re risking your health for a cheaper pill. This isn’t just about saving money—it’s about knowing exactly what you’re putting in your body. Below, you’ll find real stories and guides that show how these codes play out in everyday care—from antibiotics and antihistamines to hormone therapies and pain meds. You’ll learn how to spot the difference between a safe swap and a risky one, and how to make sure your prescriptions do what they’re supposed to—without surprises.