What Are Biosimilars? A Simple Guide for Patients

When you hear the word biosimilars, it might sound confusing-like a mix of biology and science fiction. But here’s the simple truth: biosimilars are not new drugs. They’re highly similar versions of existing biologic medicines that have been used for years. And if you’re taking a biologic for arthritis, diabetes, cancer, or another chronic condition, you might already be on one-or could be soon.

What’s a biologic, anyway?

Before we talk about biosimilars, you need to know what biologics are. These aren’t pills you swallow. Biologics are medicines made from living things-like human or animal cells, bacteria, or yeast. Think of them as tiny protein machines built inside living labs. They’re used to treat serious conditions like rheumatoid arthritis, Crohn’s disease, psoriasis, certain cancers, and even type 1 diabetes.

Unlike regular pills (like aspirin or statins), biologics are huge, complex molecules. A chemical drug is like a bicycle-simple parts, easy to copy. A biologic is more like a jet engine. Even tiny changes in how it’s made can affect how it works. That’s why you can’t just copy a biologic the way you copy a generic pill.

Biosimilars aren’t generics. Here’s why.

Generics are exact copies of small-molecule drugs. If your doctor prescribes a generic version of a blood pressure pill, you’re getting the same chemical in the same amount, made by a different company. It’s a perfect match.

Biosimilars? Not the same. Because biologics are made from living cells, no two batches are 100% identical-even from the same manufacturer. So a biosimilar isn’t an exact copy. It’s the closest possible match. Think of it like two handmade wooden chairs. They look the same, feel the same, and serve the same purpose. But if you looked under a microscope, you’d see tiny differences in the grain. That’s okay-as long as they work the same way.

The U.S. Food and Drug Administration (FDA) requires biosimilars to go through years of testing: comparing molecular structure, how the body absorbs it, how well it works, and even long-term safety data. The goal? To prove there are no clinically meaningful differences from the original biologic. That means: same dose, same side effects, same results.

How do you know if you’re getting a biosimilar?

Biosimilars have names that look strange at first. For example:

• Original biologic: infliximab (sold as Remicade)
• Biosimilar: infliximab-dyyb (sold as Renflexis)

The four-letter ending (like “-dyyb”) is there to tell them apart. It helps doctors and pharmacists track which version you’re on-especially if you have a reaction. It’s not random. It’s part of safety tracking.

Some biosimilars are labeled as “interchangeable.” That means your pharmacist can switch you to it without asking your doctor first-just like they do with generics. The first interchangeable biosimilar in the U.S. was Semglee, an insulin for diabetes, approved in 2021.

Are biosimilars safe?

Yes. Over 40 biosimilars have been approved by the FDA as of late 2023. In Europe, they’ve been used for more than 15 years with no new safety concerns. Studies show patients who switch from the original biologic to a biosimilar don’t have worse outcomes. In fact, many people stay on biosimilars for years with the same results.

The FDA doesn’t approve a biosimilar unless it’s been tested in thousands of patients. For example, the biosimilar Renflexis was studied in 541 people with rheumatoid arthritis before approval. Real-world data from hospitals and clinics show the same effectiveness and safety as the original.

Why do biosimilars matter for patients?

Cost. Biologics are expensive. Some cost over $100,000 a year. Biosimilars typically cost 15% to 30% less. That doesn’t just help insurance companies-it helps you. Lower copays. Fewer denials. More people getting the treatment they need.

For example, the biologic adalimumab (Humira) used to cost $7,000 a month. When biosimilars entered the market, the price of Humira dropped by nearly half. The biosimilars didn’t just lower their own price-they forced the original to drop too.

In the U.S., about 10% of biologic prescriptions are now for biosimilars. In Europe, it’s over 25%. As more patents expire, that number will climb. By 2028, the global biosimilars market is expected to hit $30.5 billion.

What conditions are treated with biosimilars?

Biosimilars are used for many serious conditions:

• Arthritis (rheumatoid, psoriatic, ankylosing spondylitis)
• Inflammatory bowel disease (Crohn’s, ulcerative colitis)
• Psoriasis and other skin conditions
• Certain cancers (breast, colon, lymphoma)
• Diabetes (insulin biosimilars)
• Macular degeneration (eye disease)
• Low red blood cell counts (from chemotherapy)

If your doctor prescribed a biologic for one of these, there’s likely a biosimilar option.

What if you’re already on a biologic?

You don’t have to switch. But if your doctor suggests it, don’t panic. Switching from a brand-name biologic to a biosimilar has been studied in dozens of trials. Patients who switched had no increase in side effects or loss of effectiveness. In fact, the Arthritis Foundation says switching is safe and well-supported by evidence.

Some insurance plans now require you to try a biosimilar first before covering the more expensive original. That’s not because biosimilars are inferior-it’s because they’re more affordable. And if you’re worried? Talk to your doctor. Ask: “Is there a biosimilar option for me? Has it been tested in people like me?”

What’s next?

The FDA is pushing to make biosimilars easier to access. More are coming. More will be labeled “interchangeable.” Prices will keep falling. And more patients will get the treatments they need without being priced out.

It’s not magic. It’s science. And it’s working.