What Are Biosimilars? A Simple Guide for Patients

When your doctor talks about a new medicine to treat your arthritis, diabetes, or cancer, you might hear the word biosimilar. It sounds technical, maybe even scary. But here’s the truth: biosimilars aren’t new or experimental. They’re well-tested, FDA-approved copies of powerful biologic drugs - and they can help you save money without sacrificing safety or effectiveness.

What’s the difference between a biosimilar and a generic drug?

Most people know generics. They’re the cheaper versions of pills like ibuprofen or metformin. Generics are exact chemical copies. If you break open a generic pill, you’ll find the same molecules as the brand-name version.

Biosimilars are different. They’re not copies in the same way. Why? Because biologic drugs aren’t made in a lab with chemicals. They’re made from living cells - human or animal cells grown in controlled environments. These drugs are huge, complex proteins, sometimes with sugar molecules attached. Think of them like a snowflake: no two are exactly alike, even when made by the same company.

So a biosimilar isn’t identical to the original biologic. But it’s as close as science can get. The FDA requires proof that it works the same way, has the same side effects, and is just as safe. That’s not easy. It takes years of testing, thousands of lab analyses, and clinical trials with hundreds of patients.

How do biosimilars get approved?

The FDA doesn’t just look at the final product. They dig into every step of how it’s made. The cell line used. The fermentation process. The purification methods. Even the way it’s packaged. Tiny changes in any of these steps can affect how the drug works in your body.

Before a biosimilar gets approved, the manufacturer must prove:

• The molecular structure matches the original biologic almost exactly
• It behaves the same way in lab tests (called bioactivity)
• It’s just as pure - no harmful contaminants
• Clinical studies show it works the same in patients
• Side effects are the same

For example, the biosimilar Zarxio was tested against Neupogen, a drug used to boost white blood cells after chemotherapy. In studies, patients on Zarxio had the same recovery times, infection rates, and side effects as those on Neupogen. No surprises. No hidden risks.

Are biosimilars safe?

Yes. And the data backs it up.

Biosimilars have been used in Europe for over 15 years. Millions of patients have taken them. Studies show no increase in side effects or loss of effectiveness over time. In the U.S., since Zarxio was approved in 2015, more than 30 biosimilars have been approved for conditions like rheumatoid arthritis, Crohn’s disease, psoriasis, and several types of cancer.

The American Cancer Society, the Arthritis Foundation, and the FDA all agree: approved biosimilars are as safe and effective as the original biologics. If your doctor says it’s right for you, it’s not a gamble. It’s science.

What conditions are treated with biosimilars?

Biosimilars are used for serious, long-term conditions where biologics are the standard treatment:

• Rheumatoid arthritis - drugs like adalimumab and infliximab
• Crohn’s disease and ulcerative colitis - same drugs, same results
• Psoriasis - targeting immune system overactivity
• Diabetes - biosimilar insulins like Semglee (insulin glargine)
• Cancer - trastuzumab for breast cancer, bevacizumab for colon cancer
• Eye disease - drugs for macular degeneration
• Chronic kidney disease - to help make red blood cells

These aren’t minor treatments. They’re life-changing. And biosimilars make them more affordable.

How much do biosimilars cost?

Original biologics can cost $10,000 to $20,000 a year. Some even more. Biosimilars typically cost 15% to 30% less. That’s a savings of $1,500 to $6,000 a year.

Insurance companies often push for biosimilars because they save money. Some plans require you to try a biosimilar first before they’ll pay for the brand-name drug. That’s not a punishment - it’s a smart cost-control move that still puts your health first.

In some cases, the original drug’s price has dropped too, just because biosimilars entered the market. That’s competition working the way it should.

What do biosimilar names look like?

You’ll notice something odd when you see the name of a biosimilar. It’s almost the same as the original - but with four extra letters at the end.

For example:

• Original: adalimumab (Humira)
• Biosimilar: adalimumab-afzb (Cyltezo)
• Original: infliximab (Remicade)
• Biosimilar: infliximab-dyyb (Renflexis)

That four-letter suffix isn’t random. It’s a safety feature. If something goes wrong, doctors and pharmacists can tell exactly which product caused it. That helps track side effects and keep everyone safe.

Can you switch from a biologic to a biosimilar?

Yes. And many people do.

Studies show that switching from a brand-name biologic to a biosimilar doesn’t increase side effects or make the treatment less effective. In fact, the Arthritis Foundation says switching is safe and well-studied. Patients who switched for cost reasons didn’t have worse outcomes.

But always talk to your doctor first. Never switch on your own. Your provider will check your condition, your history, and whether your insurance allows it.

What’s an “interchangeable” biosimilar?

There’s a special category: interchangeable biosimilars. These can be swapped for the original drug at the pharmacy - without your doctor having to approve it each time. Think of it like a generic pill you can pick up off the shelf.

The first one approved in the U.S. was Semglee, a biosimilar to insulin glargine (Lantus). It’s now available in pharmacies nationwide. More are expected soon.

Interchangeable doesn’t mean “better.” It just means the FDA is confident enough to let pharmacists substitute it without asking the doctor.

What should you do as a patient?

If your doctor suggests a biosimilar:

• Ask: “Is this a biosimilar? What’s the brand name?”
• Ask: “Has this been used by others with my condition?”
• Ask: “Will my insurance cover it?”
• Ask: “Can I switch from my current drug?”

Don’t assume it’s a downgrade. It’s not a cheaper, weaker version. It’s a scientifically validated alternative that works the same way.

Keep taking your medicine as prescribed. If you notice new side effects, tell your provider. But don’t stop without talking to them.

And remember: biosimilars aren’t the future. They’re here now. Over 30 are approved in the U.S., and dozens more are in development. They’re helping patients get the care they need without financial ruin.

Final thought: You’re not taking a risk - you’re making a smart choice

Biosimilars aren’t a compromise. They’re a breakthrough. They bring the power of biologic medicine - once only available to those who could afford it - to more people. And they do it without cutting corners.

The science is solid. The safety record is strong. The savings are real.

If your doctor says a biosimilar is right for you, you’re not settling. You’re choosing smart care.

If you’re on a biologic and worried about cost, ask your doctor about biosimilars. You might be surprised how much you can save - without giving up anything in quality or care.