When Can Generic Drugs Be Produced and Sold?

A generic drug company can begin producing and testing a copy of a brand-name medication as soon as it wants, even while the original is fully patented, but it cannot sell that copy until every relevant patent and FDA exclusivity period on the brand-name drug has ended or been successfully challenged and the FDA has approved the generic application. That is the short answer to when generic drugs can be produced and sold. The longer answer depends on how many patents the brand-name company holds, what kind of FDA exclusivity applies, and whether the generic manufacturer is willing to litigate its way to an earlier launch.

Producing a Generic While the Brand Is Still Patented

Federal law contains a safe harbor, often called the Bolar exemption, that lets a generic company use a patented drug for purposes reasonably related to gathering information for an FDA submission without committing patent infringement.¹ In practice, that covers formulating the product, running bioequivalence studies, and building out manufacturing.

Without the safe harbor, generic manufacturers would have to wait until every patent expired before they could even start the testing the FDA requires, and that would tack years of preparation onto every patent expiration. Instead, the work happens in parallel with the brand’s remaining patent life, so a generic can be ready to ship the day the legal barriers fall.

What Has To Expire Before a Generic Can Be Sold

Selling a generic requires clearing two separate protections that can run at the same time: patents held by the brand-name company, and exclusivity periods granted directly by the FDA. A generic manufacturer generally has to wait out whichever of the two lasts longer.

Patent Life

A patent gives its holder exclusive rights for 20 years from the date the application was filed.² Drug patents can cover the active compound, the formulation, the manufacturing process, or a specific medical use, and a single drug often carries several patents filed years apart. The last one to expire sets the earliest possible sale date on the patent side.

Brand-name companies can also recover some of the patent time they spent waiting on FDA review. Federal law allows a patent term extension of up to five years, capped so that the total patent life remaining after approval cannot exceed 14 years.³ The 20-year clock is not always the last word.

FDA Exclusivity

The FDA blocks generic approval for set periods after a brand-name drug reaches the market, independent of any patent. The main categories are:

New chemical entity: five years of exclusivity for a drug with an active ingredient the FDA has never approved. No generic application can even be submitted during the first four years.⁴
Orphan drug: seven years for a drug designated to treat a rare disease affecting fewer than 200,000 people in the U.S.⁵
New clinical investigation: three years of exclusivity for a change in use, dosage, or formulation that required new studies.
Pediatric: six months added to every existing patent and exclusivity period on the drug if the manufacturer completes FDA-requested pediatric studies.⁶

Six months of pediatric add-on sounds small until you notice it applies to every patent and exclusivity on the drug at once. For a brand with a thick patent stack, that can push the earliest generic sale date back by half a year across the board.

Looking Up the Actual Dates

Expiration dates for listed patents and exclusivities are public. The FDA publishes them in the Orange Book, a database of approved drugs and their associated protections that generic manufacturers use to plan development timelines years ahead.⁷ Once the last relevant date passes and the FDA has approved the generic, sales can begin immediately.

Selling Sooner by Challenging a Patent

Waiting is not the only option. The Hatch-Waxman Act lets a generic applicant challenge a brand-name patent it believes is invalid or would not be infringed by its product, and a successful challenge can move the sale date up by years.

The mechanism is a Paragraph IV certification filed with the FDA as part of the generic application, declaring that the listed patent is either invalid or not infringed. The applicant notifies the patent holder, which starts a 45-day clock. If the brand-name company sues for infringement within those 45 days, the FDA automatically holds up generic approval for as long as 30 months while the case runs, though a court can shorten or lengthen that stay.⁴ No lawsuit inside 45 days, and approval proceeds without the stay.

Win the challenge, and the generic can launch well before the patent would have expired. Lose it, and sales have to wait for the actual patent expiration.

The 180-Day Reward for Going First

Because patent litigation is expensive and risky, the law offers an incentive: the first generic applicant to file a Paragraph IV certification and make it to market gets 180 days as the only approved generic competitor. During that period the FDA will not approve any other generic application for the same drug.⁴ For a high-revenue medication, that half-year can be worth hundreds of millions.

The reward is not automatic once earned. Forfeiture triggers include failing to begin commercial marketing by the later of 75 days after final approval or 75 days after a favorable court ruling, withdrawing the application, amending the patent certification, failing to obtain tentative approval within 30 months of filing, and entering into an agreement with the brand-name company that a court later finds violates antitrust law.⁸

One quirk catches new entrants off guard. The 180-day window only blocks other generic applications; it does not stop the brand-name manufacturer from launching an “authorized generic,” which is a lower-priced version of its own approved product sold under a different label.⁸ The first filer often shares the market from day one.

Selling for Some Uses Only: Skinny Labels

A drug’s original compound patent can expire while later patents still cover specific medical uses. In that case a generic company can seek approval for only the uses that are no longer protected, filing what the industry calls a skinny label. The prescribing information leaves out any reference to the still-patented uses.⁹

The manufacturer cannot promote the product for any use covered by an active patent, and the labeling must carefully carve those uses out. The approach works when the unpatented uses generate enough prescribing volume to justify launching. When the still-patented indication is the drug’s main commercial use, a skinny label may not be worth the effort.

The FDA Approval That Has To Land With the Legal Clearance

Clearing patents and exclusivity gets a generic to the starting line legally. It still cannot be sold until the FDA approves the company’s Abbreviated New Drug Application. The ANDA is “abbreviated” because the generic company does not repeat the large-scale clinical trials that established the brand’s safety and effectiveness. It leans on the FDA’s earlier findings for the brand-name product and focuses on showing equivalence.⁹

Bioequivalence

The core requirement is showing that the generic delivers the same amount of active ingredient into the bloodstream at roughly the same rate as the brand-name drug.⁹ Studies on healthy volunteers produce the data, and if the performance falls within the FDA’s accepted range, the agency treats the generic as therapeutically equivalent. Appearance, flavor, and inactive ingredients can differ.

Manufacturing

Every generic manufacturer has to comply with Current Good Manufacturing Practice regulations, which set minimum standards for facilities, equipment, processes, and quality controls.¹⁰ The FDA reviews compliance as part of the ANDA and inspects facilities before and after approval. A failed inspection can delay approval or unwind it.

Fees and Review Time

Filing is expensive. For fiscal year 2026, the ANDA application fee is $358,247, domestic manufacturing facilities pay $238,943 annually, and foreign facilities pay $253,943.¹¹ The FDA’s current goal is to act on 90 percent of standard original ANDAs within 10 months of submission.¹² Acting on an application does not always mean approving it. A complete response letter asking for more information restarts portions of the clock, and many ANDAs go through multiple review cycles before final approval.

Biologics Follow a Different Clock

Everything above applies to traditional small-molecule drugs made through chemical synthesis. Biological products, which are derived from living organisms and include monoclonal antibodies and insulin, run on a separate framework. The generic equivalent is called a biosimilar.

Under the Biologics Price Competition and Innovation Act, a reference biologic receives 12 years of data exclusivity from its first FDA licensure. A biosimilar application cannot be submitted until four years after the reference product’s approval and cannot be approved until the 12-year mark.¹³ The scientific bar is also higher: a biosimilar must be shown “highly similar” to the reference product with no clinically meaningful differences, and reaching the stricter “interchangeable” designation that lets pharmacists substitute without prescriber approval requires additional evidence that the product will produce the same result in any given patient.

Biosimilar makers plan against a separate FDA database called the Purple Book, which lists licensed biological products, their biosimilars, interchangeability designations, and exclusivity expiration dates.¹⁴ If the drug you are looking at is a biologic, the timelines and rules on this page are the wrong reference.

1
Office of the Law Revision Counsel. 35 U.S. Code 271 – Infringement of Patent
2
USPTO. 2701 Patent Term
3
Office of the Law Revision Counsel. 35 U.S. Code 156 – Extension of Patent Term
4
Office of the Law Revision Counsel. 21 U.S. Code 355 – New Drugs
5
Office of the Law Revision Counsel. 21 USC 360cc – Protection for Drugs for Rare Diseases or Conditions
6
Office of the Law Revision Counsel. 21 USC 355a – Pediatric Studies of Drugs
7
U.S. Food and Drug Administration. Orange Book Preface
8
U.S. Food and Drug Administration. 180-Day Exclusivity – Questions and Answers
9
U.S. Food and Drug Administration. What Is the Approval Process for Generic Drugs
10
U.S. Food and Drug Administration. Current Good Manufacturing Practice (CGMP) Regulations
11
Federal Register. Generic Drug User Fee Rates for Fiscal Year 2026
12
U.S. Food and Drug Administration. GDUFA Reauthorization Performance Goals and Program Enhancements Fiscal Years 2023-2027
13
Office of the Law Revision Counsel. 42 U.S. Code 262 – Regulation of Biological Products
14
U.S. Food and Drug Administration. About Purple Book