FDA Orange Book: How Approved Generic Drugs Are Listed
The FDA Orange Book is the official government list that tells pharmacists, doctors, and insurance companies which generic drugs can safely replace brand-name medications. It’s not just a directory-it’s the rulebook for how generics enter the U.S. market and compete with brand-name drugs. If you’ve ever picked up a prescription and been handed a cheaper pill with a different name, the Orange Book is why that swap was allowed.
What Is the FDA Orange Book?
The official name is Approved Drug Products with Therapeutic Equivalence Evaluations. It’s been around since 1984, created under the Hatch-Waxman Act to balance two goals: letting generic drugs reach the market faster, while still protecting the patents of original drugmakers. Today, it includes over 16,000 approved drug products-both prescription and over-the-counter. About 90% of all prescriptions in the U.S. are filled with generics, and the Orange Book is the reason that’s possible.
The FDA updates the Orange Book every month. You can search it online for free through the Electronic Orange Book. It’s used daily by pharmacists, pharmacy benefit managers, and generic drug manufacturers to figure out which drugs are interchangeable and which aren’t.
How Generic Drugs Get Listed
Generic drugs don’t go through the same long, expensive testing as brand-name drugs. Instead, they use a faster process called an Abbreviated New Drug Application (ANDA). To get approved, a generic company must prove their drug is bioequivalent to the original. That means it delivers the same amount of active ingredient into the bloodstream at the same rate.
Every generic must reference a specific brand-name drug as its Reference Listed Drug (RLD). The RLD is the original drug that the FDA already approved. For example, if you’re making a generic version of Lipitor (atorvastatin), Lipitor is your RLD. The Orange Book clearly marks which product is the RLD with a "Yes" in the RLD column. All the generics that follow it get marked "No."
Once the FDA approves the ANDA, the generic drug appears in the Orange Book-usually within a month of approval. It’s not enough to just have the same ingredient. The dosage form (tablet, capsule, injection), strength, route (oral, topical, etc.), and labeling must all match the RLD.
Therapeutic Equivalence (TE) Codes: What They Mean
The Orange Book doesn’t just list drugs-it rates them. Each approved product gets a Therapeutic Equivalence (TE) Code. These codes tell you if a generic can be substituted without any clinical risk.
- A codes mean the drug is therapeutically equivalent. These are the ones pharmacists can swap freely.
- B codes mean there are potential issues. Maybe the drug has a different release mechanism, or the bioequivalence data is shaky. These aren’t automatically interchangeable.
- BN means it’s a single-source product-no generics are approved yet.
- BM means it’s a multi-source product, but no therapeutic equivalence rating has been assigned yet.
For example, a generic with an "A" code for metformin can be swapped with the brand-name Glucophage. But if a generic has a "B" code for an inhaler, your pharmacist might not be allowed to substitute it-even if the active ingredient is the same-because the delivery device matters.
Authorized Generics: The Hidden Option
There’s another kind of generic you won’t find in the Orange Book: the authorized generic. These are the exact same drug as the brand-name version, just sold without the brand name. The manufacturer is the same company that made the original. For example, the generic version of Prilosec made by AstraZeneca is an authorized generic-it’s identical to the brand, just cheaper.
Authorized generics aren’t listed in the Orange Book because they’re approved under the original brand’s New Drug Application (NDA), not an ANDA. Instead, the FDA keeps a separate list on its website called the List of Authorized Generic Drugs. This list is updated quarterly and includes the brand name, the generic version’s name, the manufacturer, and the date it launched.
Why does this matter? Sometimes, authorized generics hit the market before any traditional generic. That means patients get lower prices faster-even before the Orange Book shows any competitors.
Patents and Exclusivity: The Gatekeepers
The Orange Book doesn’t just list drugs-it lists patents. When a brand-name company gets FDA approval, they must submit any patents covering the drug’s chemical structure, formulation, or medical use. The FDA then publishes those patents in the Orange Book.
Each patent gets a number, an expiration date, and a patent use code (like U-123). These codes describe what the patent protects-for example, "U-567" might mean "treatment of high blood pressure."
These patents create legal barriers. If a generic company files an ANDA before a patent expires, the brand-name company can sue. If they do, the FDA can delay approval for up to 30 months while the court case plays out. This is called the "30-month stay."
But here’s the twist: not all listed patents are fair. Some companies file dozens of weak or irrelevant patents to delay competition-a practice called "patent evergreening." The FDA has cracked down on this in recent years, especially after new guidance in January 2023. Now, they’re more strict about what qualifies for listing.
How to Use the Orange Book
Searching the Electronic Orange Book is simple, but it helps to know what you’re looking for.
- Start with the proprietary name (brand name) or the active ingredient (like "ibuprofen").
- Filter by dosage form (tablet, liquid, patch) and route (oral, injection, etc.).
- Look at the RLD column to find the original drug.
- Check the TE code next to each generic. Only "A" codes are fully interchangeable.
- Scroll down to see patent and exclusivity information if you’re tracking market entry.
Pharmacists often use this to verify substitutions. But even they get tripped up by complex products-like combination inhalers or topical gels-where the delivery system affects how the drug works. In those cases, the TE code might say "A," but real-world experience shows the generic doesn’t work the same way.
What’s Changing in 2025
The FDA is working on a Digital Orange Book, set to launch by the end of 2025. It will be faster, more searchable, and updated in near real-time-not just monthly. It will also include better data on complex products like inhalers and injectables, where equivalence is harder to prove.
Another big change: the FDA now requires manufacturers to report more detailed data on how their generics perform in real-world use. This is partly in response to complaints from pharmacists and patients who’ve seen cases where a generic didn’t work as expected-even though the Orange Book said it was equivalent.
And the numbers keep growing. In 2023, the FDA approved 795 new generics. That’s up from 750 a year ago. The average review time for an ANDA has dropped from 36 months in 2010 to just 10 months today. That’s thanks to the Generic Drug User Fee Amendments (GDUFA), which gives the FDA more funding to review applications faster.
Why It Matters to You
If you take prescription drugs, the Orange Book affects your out-of-pocket costs. A generic with an "A" code can save you 80% or more compared to the brand. Insurance companies often require you to try the generic first.
But if your drug has a "B" code or is still under patent protection, you might be stuck paying more. That’s why it’s worth asking your pharmacist: "Is this the generic with an A code?" If it’s not, find out why.
For people with chronic conditions-like diabetes, high blood pressure, or asthma-switching between generics can be risky if the TE code isn’t clear. The Orange Book is meant to prevent that. But it’s not perfect. Some states have their own substitution laws that don’t always match the FDA’s ratings. Always double-check with your provider if you’re unsure.
The Orange Book isn’t flashy. It doesn’t make headlines. But it’s one of the most important tools in American healthcare-keeping drug prices down, ensuring safety, and letting competition work. It’s how millions of Americans get the medicine they need without going broke.
Is the FDA Orange Book the same as Drugs@FDA?
No. The FDA Orange Book only lists drugs that have been fully approved and have a therapeutic equivalence rating. Drugs@FDA includes all applications-approved, pending, tentative, and withdrawn. A drug might appear in Drugs@FDA but not in the Orange Book if it’s still under review or only tentatively approved.
Can a generic drug be pulled from the Orange Book?
Yes. If a generic drug is withdrawn from the market, fails quality control, or if its approval is revoked, it’s moved to the Discontinued Drug Product List. It no longer appears in the Active section. This can happen even if the drug was previously rated "A" for therapeutic equivalence.
Why do some generics have different TE codes even if they have the same active ingredient?
Because the formulation, delivery system, or inactive ingredients can affect how the drug works. For example, two different generic versions of an inhaler might have the same chemical, but if one uses a different propellant or valve system, it might not deliver the same dose. That’s why the FDA assigns different TE codes based on the entire product-not just the active ingredient.
Are over-the-counter (OTC) drugs listed in the Orange Book?
Yes, they’re listed-but not evaluated for therapeutic equivalence. The Orange Book includes an OTC section, but since these drugs don’t require a prescription, the FDA doesn’t assign TE codes to them. You can still see which OTC products are approved, but you can’t use the Orange Book to determine if one OTC brand can be swapped for another.
What happens if a patent in the Orange Book is invalid?
Even if a patent is later found to be invalid or improperly listed, it doesn’t automatically get removed from the Orange Book. The FDA doesn’t judge the validity of patents-it just lists what’s submitted. Only a court can force its removal. Until then, the patent still triggers the 30-month stay for generic approval.
