What Are Biosimilars? A Simple Guide for Patients

Have you been told your doctor wants to switch your medication to a biosimilar? Maybe you’ve seen the name on your prescription and wondered: What are biosimilars, really? And are they safe? You’re not alone. Many patients feel confused when they hear this term-especially if they’ve always taken the same brand-name drug for years.

Let’s cut through the jargon. Biosimilars aren’t generics. They’re not copies in the way aspirin is a copy of another aspirin. They’re something more complex-and just as important.

Biologics Are Not Like Regular Pills

First, you need to understand what biologics are. These are medicines made from living cells-like human or animal cells grown in a lab. Think of them as tiny biological machines: proteins, antibodies, or hormones that your body can’t make on its own. They treat serious conditions like rheumatoid arthritis, Crohn’s disease, cancer, diabetes, and even severe skin disorders.

Unlike regular pills made from chemicals you can mix in a beaker, biologics are grown. They’re delicate. Tiny changes in temperature, the type of cell used, or how it’s purified can affect the final product. That’s why they cost so much-sometimes over $100,000 a year.

What Exactly Is a Biosimilar?

A biosimilar is a medicine that’s made to be highly similar to an already approved biologic-called the reference product. It’s not an exact copy. You can’t make an exact copy of something grown from living cells. But it doesn’t need to be. The U.S. Food and Drug Administration (FDA) requires that biosimilars show no meaningful difference in how well they work, how safe they are, or how your body reacts to them.

Before a biosimilar gets approved, manufacturers must prove it matches the original in:

• Molecular structure
• Purity
• How it behaves in the body (bioactivity)
• Effectiveness in treating the same conditions
• Safety profile-side effects, risks, and how often they happen

They do this with hundreds of lab tests, animal studies, and often clinical trials involving hundreds of patients. For example, the biosimilar Renflexis (infliximab-abda) was tested in 541 people with rheumatoid arthritis before approval. The results? No difference in outcomes compared to the original drug, Remicade.

Biosimilars vs Generics: The Big Difference

This is where most people get confused. Generics are exact copies of chemical drugs. Take metformin for diabetes. The generic version has the same active ingredient, same shape, same dose, same everything. It’s chemically identical.

Biosimilars? Not even close to identical. Because they’re made from living cells, no two batches of a biologic are exactly alike-even from the same manufacturer. So a biosimilar isn’t trying to be identical. It’s trying to be so similar that your body can’t tell the difference.

Think of it like two handmade wool sweaters. Same pattern, same yarn, same knitter’s skill. But one was made in Canada, the other in Australia. They might have tiny differences in stitch tension or dye shade. But they keep you just as warm. That’s biosimilars.

Are Biosimilars Safe?

Yes. The FDA says biosimilars are as safe and effective as the original biologics. That’s not a guess. It’s backed by data from over a decade of use in Europe, where biosimilars have been common since the early 2000s. Millions of patients have used them without new or unexpected side effects.

Here’s what you should know:

• Biosimilars don’t cause more side effects than the original.
• They work just as well for the same conditions.
• Switching from the original biologic to a biosimilar has been studied-and shown to be safe.

Organizations like the American Cancer Society, the Arthritis Foundation, and the American Society of Hematology all agree: if your doctor recommends a biosimilar, you can trust it.

Why Do Biosimilars Cost Less?

Because they don’t need to repeat all the early research. The original biologic company spent billions developing it-clinical trials, safety studies, manufacturing setup. A biosimilar maker doesn’t have to start from scratch. They just need to prove they’ve matched it closely enough.

That saves money. Biosimilars typically cost 15% to 30% less than the original. For a drug that costs $120,000 a year, that’s $18,000 to $36,000 saved. That’s not just good for your wallet-it helps make these life-changing treatments available to more people.

What Do Biosimilars Look Like on a Prescription?

You’ll see two names:

• The generic name (like infliximab)
• The brand or biosimilar name (like infliximab-dyyb)

The four-letter suffix at the end is there to tell them apart. It’s not random-it’s required by the FDA so doctors and pharmacists know exactly which version you’re taking. If you have a reaction, they can track it back to the right product.

Don’t be alarmed if your prescription changes from Remicade to Renflexis. That’s normal. It doesn’t mean your treatment is changing-it means you’re getting the same care at a lower price.

Will Your Insurance Force You to Switch?

Possibly. Many insurance plans now prefer biosimilars because they’re cheaper. Some require you to try a biosimilar before they’ll cover the original biologic. This isn’t about cutting corners-it’s about making sure more people can afford treatment.

If you’re worried, talk to your doctor. Ask: “Is this biosimilar right for me?” and “Has it been used safely in people like me?” Most doctors are comfortable with biosimilars. They’ve seen the data. They’ve seen patients do just as well on them.

What About Interchangeable Biosimilars?

There’s a special category called “interchangeable.” This means a pharmacist can swap it for the original biologic without asking your doctor first-just like they do with generics.

The first one approved in the U.S. was Semglee, an interchangeable version of insulin glargine (Lantus). More are coming. This will make access even easier.

But even non-interchangeable biosimilars are safe. The difference is just about who makes the switch-your doctor or your pharmacist.

What Should You Do?

If your doctor suggests a biosimilar:

• Ask: “Is this the same as what I’m taking now, just cheaper?”
• Ask: “Has this been used by other patients with my condition?”
• Ask: “What happens if I switch?”

Don’t be afraid to say no if you’re uncomfortable. But know this: the science is solid. Millions of people worldwide are using biosimilars without issue.

And if you’re already on one? Keep taking it. Monitor how you feel. Report any side effects. And remember-you’re getting the same treatment, just at a better price.

The Bottom Line

Biosimilars are not second-rate drugs. They’re not experimental. They’re not shortcuts. They’re carefully tested, FDA-approved versions of complex medicines that work just like the originals. They’re helping patients get the care they need without financial ruin.

For the first time, more people with arthritis, cancer, or diabetes can access treatments that once felt out of reach. That’s progress.

And if you’re ever unsure-ask your doctor. You deserve to understand what’s in your body. You also deserve to get the best care possible, no matter your budget.