FDA Orange Book: How Approved Generic Drugs Are Listed

The FDA Orange Book is the official guide that tells you which generic drugs are approved and safe to swap for brand-name medicines. It’s not just a list-it’s the rulebook that pharmacists, doctors, and insurers use every day to decide what you can get at the pharmacy. If you’ve ever picked up a generic pill and wondered if it’s really the same as the brand, the Orange Book is why you can trust it.

What Exactly Is the FDA Orange Book?

The official name is Approved Drug Products with Therapeutic Equivalence Evaluations, but everyone calls it the Orange Book because of its orange cover. It’s been around since 1984, when Congress passed the Hatch-Waxman Act. That law was meant to do two things: let generic drugs enter the market faster, and still protect the patents of brand-name companies. The Orange Book is how the FDA makes that balance work.

It doesn’t list every drug ever made. It only includes drugs that have been approved by the FDA as safe and effective. As of 2023, it covers over 16,000 drug products-both prescription and over-the-counter. About 90% of all prescriptions in the U.S. are filled with generics, and nearly all of those are tracked here.

How Do Generic Drugs Get Listed?

Generic drug makers don’t start from scratch. Instead of running full clinical trials like brand-name companies, they submit an Abbreviated New Drug Application (ANDA). The key word here is abbreviated. They only need to prove one thing: that their drug works the same way in the body as the original.

That original drug is called the Reference Listed Drug (RLD). The FDA picks one brand-name version as the standard. Every generic must match it in strength, dosage form, route of administration, and-most importantly-how fast and how much of the drug gets into your bloodstream. That’s called bioequivalence.

Once the FDA approves the ANDA, the generic gets added to the Orange Book. You’ll see it listed right next to the RLD. The RLD is marked with a “Yes” in the RLD column. The generic gets a “No.” Simple.

Therapeutic Equivalence Codes: What Do the Letters Mean?

Not all generics are treated the same. The Orange Book gives each drug a Therapeutic Equivalence (TE) Code. These are one or two letters that tell you whether a generic can be swapped without worry.

• A codes mean the drug is therapeutically equivalent. You can substitute it freely. For example, a generic version of Lipitor with an “A” code is considered interchangeable with the brand.
• B codes mean there’s a problem. Maybe the drug isn’t reliably absorbed, or it’s a complex delivery system like an inhaler. These aren’t automatically interchangeable. Pharmacists might need to check with your doctor before switching.
• BN codes mean it’s the only product available for that drug. No generics exist yet. That’s often because the patent is still active.

These codes matter. If you’re on a Medicaid or Medicare plan, your pharmacy might only be allowed to dispense drugs with “A” codes unless your doctor says otherwise. That’s why the Orange Book isn’t just a reference-it’s a legal tool.

What About Authorized Generics?

There’s another kind of generic you might not know about: authorized generics. These are brand-name drugs made by the same company but sold without the brand name. For example, the maker of Claritin might sell a generic version of loratadine under its own label, right alongside the branded version.

Here’s the twist: authorized generics are not listed in the Orange Book. Why? Because they’re approved under the same New Drug Application (NDA) as the brand. The FDA tracks them separately on a different list-updated quarterly-called the List of Authorized Generic Drugs. So if you see a generic that looks exactly like the brand but costs less, it’s probably an authorized generic. But you won’t find it in the Orange Book.

Patents and Exclusivity: The Hidden Rules

The Orange Book doesn’t just list drugs. It also lists patents. This is where things get complicated.

When a brand-name company gets FDA approval, they must tell the FDA which patents cover their drug. That includes patents on the chemical itself, how it’s made, or how it’s used. The FDA doesn’t decide if those patents are valid. They just publish what the company gives them.

Each patent gets a number, an expiration date, and a patent use code (like U-123). These codes tell you exactly which medical condition the patent protects. For example, a patent might cover using a drug to treat high blood pressure, but not heart failure. That’s important because generic companies can still make the drug for the unpatented use.

When a generic company files an ANDA, they have to say whether they’re challenging any of these patents. If they do, the brand-name company can sue. That triggers a 30-month clock where the FDA can’t approve the generic-even if it’s ready. This is called the “30-month stay.” It’s a legal pause, not a scientific one.

Some critics say companies abuse this system by listing dozens of weak patents-what’s called “patent thickets”-to block generics. The FDA says it’s cracking down. In 2023, they updated rules to prevent listing patents that don’t clearly cover the approved use.

How to Use the Electronic Orange Book

The FDA keeps the Orange Book online. You can search it for free at the Electronic Orange Book website. Here’s how to find what you need:

1. Search by active ingredient (like “metformin”) to see all drugs with that component.
2. Or search by proprietary name (like “Glucophage”) to find the brand and all its generics.
3. Look at the dosage form and route (e.g., tablet, oral) to narrow results.
4. Check the TE code and RLD column to see which ones are interchangeable.
5. Scroll down to the patent section to see if any are still active.

It’s not always easy. Combination drugs-like those with three active ingredients-can be messy. One pharmacist on a forum said searching for Trelegy Ellipta took 20 minutes because the system didn’t group the ingredients intuitively.

Why This Matters to You

If you’re taking a generic drug, the Orange Book is why you’re paying less. It’s why your insurance lets you switch from brand to generic without extra cost. It’s why your pharmacist can legally give you a different pill that works the same.

But it’s also why sometimes you get a different generic than last time. If the first one has a “B” code, your pharmacy might switch to another with an “A” code. Or if a patent expires, a new generic might hit the market and replace the old one.

For people on tight budgets, the Orange Book is a lifeline. A 2023 Congressional Budget Office report found that when multiple generics are available (thanks to “A” codes), prices drop 18-22% compared to single-source drugs. That’s hundreds of dollars a year for chronic conditions like diabetes or high cholesterol.

What’s Changing in 2025?

The FDA is working on a new version called the Digital Orange Book. It’s supposed to be faster, more accurate, and updated in real time-not just monthly. The goal is to make it easier for pharmacies, hospitals, and even apps to pull data directly into their systems.

They’re also testing more detailed therapeutic equivalence ratings for tricky drugs like inhalers, eye drops, and topical creams. These aren’t simple pills. The way they’re delivered can affect how well they work. Right now, the Orange Book treats them like tablets. That’s changing.

The bottom line? The Orange Book isn’t going away. It’s evolving. And it’s still the most important tool we have for making sure generic drugs are safe, effective, and affordable.