Biologics are FDA-approved medications with well-established safety profiles. They increase the risk of certain infections and require pre-treatment screening and ongoing monitoring as directed by your prescriber.

What is the difference between a biologic and a biosimilar?

A biosimilar is FDA-approved to be highly similar to an already-approved biologic, with no clinically meaningful differences in safety or efficacy.

How Do Biologics Work?

Q: How do biologics work?

Biologics precisely target specific proteins or immune cells involved in inflammation — such as TNF-alpha, IL-17, IL-23, or JAK enzymes — reducing disease activity with minimal impact on the rest of the immune system.

A plain-language explanation of biologic medications and their mechanisms of action

Quick Answer

Biologics are complex protein medicines made from living cells (bacteria, yeast, or mammalian cells). Unlike traditional pills that broadly suppress the immune system, biologics work by precisely targeting specific proteins or cells involved in the inflammatory process. Different biologics block different targets — such as TNF-alpha, IL-17A, IL-23, IL-6, or JAK enzymes — reducing inflammation while leaving most of the immune system intact.

What Makes a Biologic Different from a Regular Drug?

Traditional drugs (like ibuprofen or methotrexate) are small chemical molecules made by chemical synthesis. Biologics are large, complex proteins manufactured by living cells using biotechnology. Because of their size and complexity, biologics cannot be taken as pills — they would be digested in the stomach and must be given as injections or IV infusions.

Biologic Drug Classes and How They Work

🎯 TNF-alpha Inhibitors

Block tumor necrosis factor-alpha (TNF-α), a key inflammation-driving protein. Examples: Humira (Adalimumab), Enbrel (Etanercept), Remicade (Infliximab), Simponi (Golimumab), Cimzia (Certolizumab pegol). Used in RA, psoriasis, Crohn's, UC, AS.

🎯 IL-23 Inhibitors

Block interleukin-23 (IL-23), which drives Th17 cell-mediated inflammation in skin and gut. Examples: Skyrizi (Risankizumab), Tremfya (Guselkumab), Stelara (IL-12/23), Ilumya (Tildrakizumab), Omvoh (Mirikizumab). Used in psoriasis, Crohn's, UC.

🎯 IL-17 Inhibitors

Block interleukin-17A or IL-17A/F, key mediators of skin and joint inflammation. Examples: Cosentyx (Secukinumab), Bimzelx (Bimekizumab). Used in psoriasis, PsA, AS.

🎯 IL-4/IL-13 Inhibitors

Block type 2 inflammation driven by IL-4 and IL-13, key in allergic and eczema-related disease. Example: Dupixent (Dupilumab). Used in atopic dermatitis, asthma, nasal polyps.

🎯 IL-6 Inhibitors

Block the IL-6 receptor, reducing systemic inflammation in RA and related conditions. Examples: Actemra (Tocilizumab), Kevzara (Sarilumab). Used in RA, giant cell arteritis.

🎯 JAK Inhibitors

Inhibit Janus kinases (JAK enzymes) that mediate inflammatory cytokine signaling inside cells. Examples: Rinvoq (Upadacitinib, JAK1), Xeljanz (Tofacitinib, JAK1/3), Sotyktu (Deucravacitinib, TYK2). Taken orally (pills).

Biologics modulate (selectively reduce) specific parts of the immune system, rather than broadly suppressing it the way steroids do. This targeted approach reduces disease activity while leaving much of the immune system intact. However, all biologics increase the risk of certain infections to some degree — which is why pre-treatment testing (TB, hepatitis B) and ongoing monitoring are important.

No. Biologics are not chemotherapy. They are targeted immunomodulatory therapies. Some low-dose chemotherapy drugs (like methotrexate) are used alongside biologics for RA, but the biologics themselves are a distinct class of medication.

A biosimilar is an FDA-approved biological product that is highly similar to an already-approved biologic (the reference product) with no clinically meaningful differences in safety, purity, or potency. Biosimilars are approved after rigorous scientific comparison to the reference biologic. Examples include biosimilars for Humira, Remicade, and Stelara.

📚 Sources & Further Reading

Content developed with reference to leading health organizations, peer-reviewed research, and FDA prescribing information.

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How Biologics WorkFDA

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Monoclonal AntibodiesWikipedia

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Biologic MechanismsNIH/NCBI

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Biologic TherapyNCI

Medical Disclaimer: Educational content reviewed by the BiologicHealthPlus Clinical Team. Consult your healthcare provider for personalized advice. Last reviewed: August 2026.

Disclaimer: This page is for educational purposes only and does not constitute medical advice. Last updated: July 2026.