When Do Drug Patents Expire? Understanding the 20-Year Term and What Really Happens

Most people think drug patents last 20 years. That’s what you hear on TV, in news headlines, even from your pharmacist. But if you’ve ever wondered why a brand-name drug still costs hundreds of dollars years after it was first approved, the answer isn’t simple. The 20-year clock doesn’t start when the drug hits the shelf-it starts when the company files the patent, often a decade before the drug even reaches patients.

The 20-Year Clock Starts Before the Drug Is Even Approved

Under U.S. law, a drug patent lasts 20 years from the earliest filing date of the patent application. That’s not when the drug is tested in humans, not when it gets FDA approval, and definitely not when it’s sold in pharmacies. It’s when the pharmaceutical company first submits the patent paperwork to the USPTO. Most companies file patents during early clinical trials, sometimes even before Phase I testing. That means by the time a drug gets approved, five to ten years of its patent life are already gone.

Take Humira, for example. The patent was filed in 1997. It got FDA approval in 2002. But the 20-year clock didn’t reset-it kept ticking. By the time the last major patent expired in 2023, nearly 26 years had passed since filing. That’s because the company layered patents: one for the active ingredient, another for the delivery device, others for how it’s used to treat rheumatoid arthritis, Crohn’s disease, and psoriasis. Each had its own 20-year term, but they all started from the same original filing date.

Patent Term Extension: The Legal Lifeline

Here’s where things get real. The Hatch-Waxman Act of 1984 gave drugmakers a way to get back some of that lost time. If the FDA took more than three years to review the drug, or if there were delays in the approval process, the company could apply for a Patent Term Extension (PTE). This can add up to five extra years of protection-but with a catch.

The total time a drug can be protected from generic competition is capped at 14 years from the date it’s approved by the FDA. So even if a company gets the full five-year extension, if the drug was approved eight years after the patent was filed, the total protection is only 14 years, not 25. That’s why some drugs expire sooner than others, even if they were filed around the same time.

And here’s the kicker: the company has just 60 days after FDA approval to apply for this extension. Miss the deadline? You lose it. No appeals. No second chances. Many smaller companies miss this window simply because they don’t have a dedicated patent team.

It’s Not Just Patents-There’s Also Regulatory Exclusivity

Even if a patent expires, that doesn’t mean generics can jump in right away. The FDA gives out separate protections called regulatory exclusivity. These are not patents-they’re legal barriers built into drug approval rules.

• New Chemical Entity (NCE) exclusivity: 5 years. No generic can even submit an application during this time.
• Orphan Drug Exclusivity: 7 years for drugs treating rare diseases (fewer than 200,000 U.S. patients).
• New Clinical Investigation exclusivity: 3 years for new uses, dosages, or formulations that require new clinical trials.
• Pediatric Exclusivity: 6 months added to any existing patent or exclusivity period if the company does extra studies on how the drug affects children.

That means a drug could have its patent expire in 2027, but still be protected until 2030 because of pediatric exclusivity. One patient in a Reddit thread in early 2024 shared that their insurance switched them from a brand-name drug to a generic-only to find the copay jumped from $50 to $200 during the extra 6-month pediatric window. The patent had expired, but the exclusivity hadn’t. No one told them.

The Patent Cliff: What Happens When Protection Ends

The moment the last patent or exclusivity period ends, the market shifts. That’s called the patent cliff. Generic manufacturers can finally file applications. And they do-fast.

For small molecule drugs (the kind made from chemicals), generic versions typically capture 35% of the market within six months and over 90% within 18 months. Prices drop by 60% to 80% in the first year. Eliquis, a blood thinner, lost 62% of its average wholesale price after generics entered in 2023. By 2024, it was being sold for less than $10 a month in many states.

But biologics-complex drugs made from living cells, like Humira or Enbrel-are different. Their generics are called biosimilars. They’re harder to copy, harder to approve, and slower to gain trust. Even after patent expiry, biosimilars often take 2-3 years to reach 40-60% market share. Some patients still stick with the brand because their doctors won’t switch them, or their insurance doesn’t cover the biosimilar.

How Companies Stretch Protection: Evergreening and Layering

Pharmaceutical companies don’t wait for the patent to expire. They plan years ahead. A 2023 study found that 78% of drugs with upcoming patent cliffs use some kind of lifecycle management strategy.

One common tactic is evergreening: filing new patents on minor changes-like a new pill coating, a different dosage form, or a new delivery device. The FTC found that these strategies can delay generic entry by 2-3 years on average. For example, AstraZeneca’s Tagrisso, a lung cancer drug, had its main patent expire in 2026. But it has 12 other patents covering combination therapies, dosing schedules, and manufacturing methods. Those extend protection until 2033.

Another trick? Filing patents in multiple countries. A drug might lose protection in the U.S. in 2025 but still be protected in Japan, Germany, or Brazil until 2030. That’s why some patients travel abroad to buy cheaper versions.

What’s Changing Now? New Rules and Legal Battles

In early 2024, Congress introduced a bill called the Restoring the America Invents Act. If passed, it would eliminate certain patent term adjustments, cutting average protection by 6-9 months. The USPTO is also rolling out automated systems to speed up patent reviews, which could reduce delays-and shorten PTE eligibility.

Meanwhile, the Patent Trial and Appeal Board (PTAB) is becoming a battleground. Between 2019 and 2023, 62% of pharmaceutical patents were challenged through Inter Partes Review (IPR) proceedings. Generic companies are using this faster, cheaper alternative to court to knock out patents before they expire.

And then there’s the global pressure. The World Health Organization has called for reducing patent terms to 15 years to improve access to medicines. The pharmaceutical industry, led by PhRMA, pushes back, saying the $2.3 billion average cost to develop a drug justifies the current system.

Who’s Really Affected?

It’s not just drugmakers and generics. It’s patients. It’s insurers. It’s pharmacies.

When a drug’s patent expires, prices drop. That’s good news for patients with high-deductible plans or no insurance. But if a drug has pediatric exclusivity, or if the first generic applicant gets 180 days of market exclusivity, patients might face higher costs during that window. Some insurers don’t update their formularies fast enough. Patients get stuck paying brand prices even when generics are available.

And for older adults on fixed incomes, the timing matters. A drug that costs $150 a month under patent might drop to $20 after generics arrive. But if the switch happens mid-year, and their insurance resets the deductible, they could pay thousands out of pocket before the savings kick in.

How to Find When a Drug’s Patent Expires

There’s no single public tool that gives you exact dates for every drug. But here’s what you can do:

• Check the FDA’s Orange Book-it lists all patents and exclusivity periods for approved drugs. Search by drug name.
• Use DrugPatentWatch or Clarivate’s Cortellis (both are industry tools, often accessible through libraries or hospitals).
• Call your pharmacy and ask if they have a generic version available. If not, ask why.
• Look up the drug’s FDA approval date. Add 5 years for NCE exclusivity. Then check if there’s pediatric or orphan exclusivity.

Most people don’t know this, but the FDA requires drugmakers to update patent information within 30 days of approval. If the Orange Book doesn’t match what your pharmacist says, ask for a copy of the official filing.

What’s Next?

The next five years will see over $268 billion in revenue lost to patent expirations, with 2025 being the peak year. Drugs like Copaxone, Xarelto, and Trulicity are all on the list. If you’re on one of these, prepare. Talk to your doctor. Ask about generics. Check your insurance plan’s formulary. Don’t assume the brand is still the only option.

Patents aren’t just legal documents-they’re financial timelines that affect your wallet, your health, and your access to care. Understanding them isn’t just for lawyers or CEOs. It’s for anyone who takes medication.