Biosimilars
What Is a Biologic?
A biologic is a medicine made from living cells using advanced biotechnology. Biologics are used to treat many diseases, including rheumatic diseases such as rheumatoid arthritis, psoriatic arthritis, lupus, vasculitis, inflammatory muscle diseases, and ankylosing spondylitis.
Biologics work by targeting specific parts of the immune system that cause inflammation. For example, some biologics block proteins such as tumor necrosis factor (TNF), interleukin (IL)-6, IL-17, IL-23, B cells, or T-cell activation pathways to reduce inflammation and prevent damage to joints and organs.
What Is a Biosimilar?
A biosimilar is a biologic medicine that is highly similar to an already approved biologic medicine, known as the “reference product.” Because biologics are made from living cells, biosimilars are not exact copies, but they must have no clinically meaningful differences in safety, effectiveness, purity, or strength compared with the original biologic.
Biosimilars undergo extensive testing and review by the U.S. Food & Drug Administration (FDA) before approval. This includes laboratory testing, manufacturing review, pharmacologic studies, and clinical trials to confirm they work as well and are as safe as the original biologic.
Biosimilars and their reference biologics are expected to have the same clinical benefits, safety profile, risks and side effects, strength and dosage, and route of administration.
Are Biosimilars the Same as Generic Drugs?
No. Biosimilars are different from generic drugs.
Generic drugs are exact chemical copies of brand-name medications because traditional drugs are made through predictable chemical processes. In contrast, biologics are large, complex proteins produced by living cells, making it impossible to create an identical copy.
A helpful example is building two houses from the same blueprint. The houses may have minor differences, such as paint color or door handles, but they function the same way and are structurally equivalent. Similarly, the small differences allowed in biosimilars do not affect how the medication works.
Are Biosimilars Safe?
Yes. The FDA requires a strict review process to make sure the biosimilar is safe and matches as closely as possible to the biologic it is based upon.
For FDA approval, a biosimilar must be tested and go through many clinical trials with a wide range of patients. When this testing is done, the results must match up to the original drug to make sure they are safe and effective, with no significant differences from the original.
Do All Biologics Have a Biosimilar Option?
No. For rheumatic diseases, there are a few biologic drugs with biosimilar options available. These drugs treat diseases such as rheumatoid arthritis, lupus, certain forms of vasculitis, inflammatory muscle diseases, psoriatic arthritis, juvenile idiopathic arthritis, Crohn’s disease, ulcerative colitis, and ankylosing spondylitis. However, biosimilars are a growing part of treatment as more options become available.
How Do You Take It?
Biosimilars can be given by intravenous (IV) infusion (usually given in a hospital or clinic by a nurse) or by an injection under the skin. The injection can be given at home or in a clinic depending on the medication. The frequency and dose depend on the specific biosimilar drug prescribed and should be taken under the direction of a rheumatology healthcare provider.
When Should a Patient Start or Switch to a Biosimilar?
The decision to start or switch to a biosimilar should be made with a rheumatology healthcare provider so that you can discuss if it is right for you. The biosimilar and the original biologic may have different prices. Patients should talk to their rheumatologist and insurance provider for cost details.
Additional Resources
Sources:
- Arthritis Foundation Drug Guide: Biosimilars
- GoodRx Health: What Are Biologics and Biosimilars? Definitions and Examples
- U.S. Food & Drug Administration: Biosimilar Basics for Patients
Updated May 2026 by Howard Yang, MD, RhMSUS, and reviewed by the American College of Rheumatology Communications and Marketing Committee.
This information is provided for general education only. Individuals should consult a qualified health care provider for professional medical advice, diagnosis and treatment of a medical or health condition.