By 2025, more than 40 biosimilars have been approved in the U.S. - drugs designed to be nearly identical to expensive biologic medicines like Humira, Enbrel, and Lantus. They’re proven safe, effective, and cost 10% to 33% less. But if you’re a patient trying to get one, you might as well be fighting a maze. Insurance companies aren’t making it easy. In fact, they’re often making it harder than getting the original brand-name drug.
Why Biosimilars Are Still Hard to Get
Biosimilars aren’t generics. They’re not simple chemical copies like the ones you get for blood pressure pills. They’re made from living cells - complex, expensive to produce, and tricky to replicate exactly. That’s why they’re called biosimilars, not generics. The FDA approved the first one, Zarxio, back in 2015. Since then, over 70 have been cleared. But only about 40 are actually on the market. And even when they are, insurance plans rarely make them the obvious choice.Take Humira, the best-selling drug in U.S. history. It costs around $5,000 a month. Eight biosimilars now exist as cheaper alternatives. Yet, according to JAMA Network data from June 2024, only half of Medicare Part D plans cover even one of them. And when they do? They’re usually placed on the same high-cost tier as Humira. That means you pay the same out-of-pocket price - $1,150 to $1,200 a month - whether you get the brand or the biosimilar. Where’s the incentive to switch?
Prior Authorization: The Hidden Gatekeeper
Nearly every insurance plan that covers biosimilars also requires prior authorization. That’s a form your doctor has to fill out, often with lab results, treatment history, and proof you’ve tried other drugs first. It can take 3 to 14 days to get approved. For someone with rheumatoid arthritis or Crohn’s disease, waiting two weeks for treatment isn’t just inconvenient - it’s dangerous.Here’s the kicker: 98.5% of plans require prior authorization for both Humira and its biosimilars. Not one plan makes the biosimilar easier to get. In fact, some require you to try the biosimilar first before they’ll approve the brand-name drug. That’s called step therapy. A case study in Rheumatology Advisor showed a patient with severe arthritis waited 28 days because their insurer forced them to try a biosimilar first. The patient’s symptoms worsened. Their doctor had to appeal. It was exhausting.
Doctors are spending 3 to 5 hours a week just handling these requests, according to a 2024 survey by the Alliance for Patient Access. That’s time they could be seeing patients - not chasing paperwork.
Tier Placement: The Real Barrier
Insurance plans use tiers to control costs. Tier 1 is cheap generics. Tier 4 or 5 is specialty drugs - the expensive ones like biologics. Biosimilars almost always land in Tier 4 or 5. That means you pay a percentage of the drug’s price, not a flat copay. If the drug costs $5,000, and your coinsurance is 33%, you pay $1,650 a month. Even if the biosimilar is $500 cheaper, you’re still paying $1,500. That’s not savings - that’s a penalty.According to the Center for Biosimilars, only 1.5% of plans put biosimilars on a lower tier than the reference drug. That’s almost zero. Meanwhile, Medicare Part D formularies in 2025 placed Humira and its biosimilars on the exact same tier - 99% of the time. No preference. No discount. No reward for choosing the cheaper option.
And it’s worse for insulin biosimilars. Eight are approved. Less than 10% of Medicare plans cover them. Even though insulin costs can be life-or-death for diabetics, insurers are still blocking access to cheaper versions.
Why PBMs Are Playing Hardball
The real power behind these rules isn’t the insurance company - it’s the pharmacy benefit managers (PBMs). These are the middlemen that negotiate drug prices and decide what goes on formularies. Express Scripts, OptumRx, and CVS Caremark control most of the market. And they’ve changed tactics.In 2025, Express Scripts completely removed Humira from all its commercial formularies. Not just restricted - gone. If you want Humira, you’re out of luck. But they put multiple biosimilars on preferred tiers with lower coinsurance (25% instead of 33%). That’s not an accident. It’s a strategy: force patients to switch by removing the brand entirely.
Other PBMs are following. This is a shift from passive coverage to active exclusion. But here’s the problem: it only works if the biosimilar is affordable and accessible. If patients can’t afford the coinsurance, or if the prior authorization takes weeks, they still won’t get treated. And if their doctor doesn’t know which biosimilars are covered, they’ll just prescribe the brand - because it’s easier.
Patients Pay the Price
The numbers don’t lie. Medicare Rights Center found that when biosimilars and Humira are on the same tier, patients pay almost the same amount out of pocket. The biosimilar might be $50 cheaper per month - but that’s not enough to motivate a change. Especially when you’re already paying $1,200 a month.For many, that’s not just expensive - it’s unaffordable. One patient in Texas skipped doses to stretch her Humira supply. She ended up in the ER. Her insurance didn’t care. The biosimilar was available. But her plan didn’t make it easy to get.
And it’s not just Medicare. Commercial plans are doing the same. UnitedHealthcare, Cigna, and Centene still don’t cover any insulin biosimilars - even though they’ve been approved for years. The message? We’ll cover the expensive drug. But the cheaper version? Not yet.
What’s Changing - and What’s Not
There’s some progress. The Congressional Budget Office estimates biosimilars could save the U.S. healthcare system $54 billion over the next decade. CMS started requiring plans to report biosimilar coverage in 2024. And in 2025, the Office of Inspector General pushed for stricter rules on tier placement.But change is slow. The FDA has approved dozens of biosimilars. The science is solid. The savings are real. The problem isn’t the drug - it’s the system. Insurance rules are designed to protect revenue, not patients.
Some PBMs say tier alignment reflects clinical equivalence. But that’s not true. Clinical equivalence doesn’t mean financial equivalence. If two drugs work the same, why should one cost twice as much out of pocket? The FTC has called these practices anti-competitive. Former FDA Commissioner Dr. Scott Gottlieb said they violate the spirit of the law meant to bring down biologic prices.
What Patients Can Do
You’re not powerless. Here’s what you can do:- Ask your doctor: "Is there a biosimilar available for my drug?" Don’t assume they know.
- Call your insurer. Ask: "Is the biosimilar on a lower tier than the brand?" If not, ask why.
- Request a formulary exception. If your doctor says you need the brand, they can appeal.
- Check your plan’s formulary online. Look up the drug name and see what tier it’s on.
- If you’re on Medicare, use the Medicare Plan Finder. Compare plans during open enrollment - coverage changes every year.
It’s not easy. But if you don’t ask, you won’t get it.
The Road Ahead
The U.S. biosimilar market grew to $15.3 billion in 2024 - up from $12 billion in 2022. But market share is still only 23% for adalimumab drugs. In Europe, it’s over 80%. Why? Because European insurers actively push biosimilars to the front of the line. They put them on lower tiers. They waive prior authorization. They let pharmacists substitute them automatically.The U.S. could do the same. But right now, the system is broken. Insurance companies aren’t saving money - they’re just shifting costs to patients. And the people who need these drugs the most are the ones paying the highest price.
If you’re paying over $1,000 a month for a biologic, you deserve better. The science says biosimilars work. The numbers say they save money. The question is: will insurance ever make it easy for you to get them?
Why aren’t biosimilars cheaper for patients if they cost less to produce?
Biosimilars are cheaper for insurers to buy - but insurance plans often place them on the same high-cost tier as the brand-name drug. That means patients pay the same coinsurance - usually 25% to 33% of the drug’s list price. Even if the biosimilar costs $500 less, the patient’s out-of-pocket bill barely changes. Without lower-tier placement, there’s no financial incentive to switch.
Can pharmacists substitute a biosimilar for the brand-name drug automatically?
Only if the biosimilar is designated as "interchangeable" by the FDA. As of 2025, only a few biosimilars - like adalimumab-adbm (Cyltezo) - have this status. But even then, substitution is limited to low-concentration versions of Humira, which are rarely prescribed. Most biosimilars require a new prescription. Pharmacists can’t swap them in without doctor approval.
Do all insurance plans cover biosimilars?
No. As of 2025, only about half of Medicare Part D plans cover any biosimilar for Humira. For insulin biosimilars, coverage drops below 10%. Many commercial insurers, including UnitedHealthcare and Cigna, still don’t cover any insulin biosimilars. Coverage varies wildly by plan, drug, and state.
Why do insurers require prior authorization for biosimilars if they’re approved by the FDA?
FDA approval means the drug is safe and effective - not that it’s affordable or preferred. Insurers use prior authorization to control costs and steer patients toward drugs that give them rebates or discounts. Even if a biosimilar is cheaper, insurers may still require proof you’ve tried other drugs first. It’s a financial tactic, not a medical one.
Can I switch from a brand-name biologic to a biosimilar without my doctor’s approval?
No. Even if your insurer approves the biosimilar, you still need a new prescription from your doctor. Unlike generic pills, biosimilars are not automatically substitutable. Your doctor must write a new order. Some states allow pharmacist substitution for interchangeable biosimilars, but that’s rare and limited to specific drug formulations.
Are biosimilars covered under Medicare Part D?
Yes - but inconsistently. In 2025, 78% of Medicare Part D plans covered at least one biosimilar for Humira, up from 62% in 2023. But 99% of those plans placed the biosimilar on the same tier as the brand, meaning patients pay nearly the same out-of-pocket cost. Coverage is better than it was, but the financial incentive to switch remains minimal.
What’s the difference between a biosimilar and a generic drug?
Generics are exact chemical copies of small-molecule drugs - like aspirin or metformin. Biosimilars are complex proteins made from living cells. They’re highly similar to the original biologic, but not identical. That’s why they require more testing and cost more to make. They’re not interchangeable unless the FDA specifically designates them as such.
Why are PBMs blocking insulin biosimilars even though they’re approved?
Insulin is a high-volume, high-rebate drug. Brand-name insulin manufacturers pay PBMs large rebates to keep their products on preferred tiers. Switching to a biosimilar would cut those rebates. Even though biosimilars cost less, PBMs make more money keeping the brand on formularies. That’s why only 10% of Medicare plans cover insulin biosimilars - despite eight being approved.
